document_title: Legal drinking age

question_text: how old do you have to drink in spain

question_tokens: how old do you have to drink in spain

root

text: Legal drinking age

text: Africa[edit]

text: The most common minimum age to purchase alcohol in Africa is 18. Although it varies from the lowest age limit in Ethiopia being only 15 years, Zimbabwe with a minimum purchase age of 16 years, Gambia with a age limit of 17 years and Uganda where the minimum legal purchase age is 18 but minors aged 16 or 17 may consume a glass of beer, wine or cider with a meal at a restaurant. Cameroon and Egypt are the only countries in Africa with a minimum purchase age of 21 years. However Algeria, Angola (except Luando Province), Central African Republic, Comoros, Equatorial Guinea, Gabon, Guinea-Bissau, Morocco, Togo, Tunisia and the Western Sahara have no laws on the book restricting the sale of alcohol to minors. And in Libya, Somalia and Sudan the sale, production ond consumption of alcohol is completely prohibited.

tag: p

text:
Country
State/Region/Province
De jure
Notes

Drinking age
Purchase age

 Algeria
None[2]

 Angola

None[2]
There is no national legislation prohibiting the sale of alcohol to minors.

Luanda Province:
18[3]
Legislation in Luanda Province:
It is illegal to sell alcoholic beverages to anyone under the age of 18. It is also illegal for minors to buy and consume alcohol.[3]

 Botswana
None[4]
18[4]
It is illegal for any person with a liquor license to sell or supply alcoholic beverages to minors under the age of 18 years. Because the law only applies to licensees it is not illegal for minors to buy, consume or possess alcoholic beverages.

 Burundi
None[5]
18 (None if accompanied by parent or legal guardian)[5]
It is illegal for any person with a liquor license to sell or supply alcoholic beverages to unaccompanied minors under the age of 18 years.

 Cameroon
21/18 (if accompanied by a person 21 years of age or older)[6]
It is illegal for any person with a liquor license, to sell or supply alcoholic beverages to anyone under 18 years of age. The law permits adults fromn the ages 18 to 21 to consume, purchase and buy alcoholic beverages if accompanied by a person 21 years of age or older. Anyone over the age of 21 years may buy or consume alcohol unaccompanied.

 Cape Verde
None[7]
18[7]
It is illegal for any person to sell or supply alcoholic beverages to minors under the age of 18 years.

 Central African Republic
None[2]

 Comoros
None[2]

 Egypt
21[2]

 Equatorial Guinea
None[2]

 Eritrea
None[8]
18[8]
It is illegal for any person to sell or serve alcoholic beverages to minors under the age of 18 years.

 Ethiopia
None[9]
15[9]
It is illegal for any person to sell, offer, serve or allow to serve alcoholic beverages "in substantial quantities" to any infant or young person. The criminal code defines a young person as any person under the age of 15 years. But the Criminal Code states: "Whoever endangers the health of another, intentionally and unscrupulously, by administering or serving, or by causing or permitting to be administered or served, to minors (defined as anyone under the age of 18 years) (...) alcoholic beverages or spirituous liquors of such kind or in such quantity as to make their injurious effect certain or probable, is punishable with simple imprisonment not exceeding one year, and fine."

 Gabon
None[2]

 Gambia
None[10][2]
17[10][2]
It is illegal to sell, serve or supply alcoholic beverages to child or young person. A "young person" is defined as anyone under the age of 17 by the Children and Young Persons Act, 1949 Section 2.

 Ghana
18[11]

 Guinea-Bissau
None[2]

 Kenya
None[12]
18[12]
It is illegal to sell, serve or supply alcoholic beverages to anyone under the age of 18 years.

 Lesotho
18[13]
It is illegal to sell, serve or supply any alcoholic beverage to a minor under the age of 18 years. It is also illegal for minors to consume, buy or attempt to buy alcohol.

 Liberia
None
18[2]
It is illegal to sell, serve or supply alcoholic beverages to anyone under the age of 18 years.

 Libya
Illegal[14]
Previously Article 498 of the Libyan Penal Code prohibted the sale of acloholic beverages to juveniles under the age of 16 years.[2]

 Malawi
None
18[15]
It is illegal to sell, serve or supply alcoholic beverages to anyone under the age of 18 years.

 Mauritius
None
18[16]
It is illegal to sell, serve or supply alcoholic beverages to anyone under the age of 18 years.

 Morocco
None[2]

 Mozambique
18[17]

 Namibia
None
18[18]
It is illegal to sell, serve or supply alcoholic beverages to anyone under the age of 18 years.

 Niger
18[2]

 Nigeria
18[2]

 Republic of the Congo
None
18[19]

 Rwanda
18[2]

 Senegal
18[20]

 Seychelles
18[2]

 Somalia
Illegal[21]

 South Africa
18
The parent, adult guardian of a minor or a person responsible for administering a religious sacrament, may on occasion supply to that minor a moderate quantity of liquor to be consumed by the minor in the presence and under the supervision of that parent, guardian or other person.[22]

 South Sudan
18[2]

 Sudan
Illegal[23]

 Swaziland
18[2]

 Tanzania
None
18[24]

 Togo
None[2]

 Tunisia
None[2]

 Uganda
None[25]
18
16 (wine, beer, porter, cider, perry or native liquor with meal)[25]
It is illegal for any licensee to sell, serve or supply alcoholic beverages to anyone under the age of 18 years. The law provides a exception for anyone who is 16 or 17 years of age, and consumes a fermented alcoholic drink with a meal, in a part of a licensed premises that serves meals and is not a bar.

 Western Sahara
None[2]

 Zambia
18[26]
It is illegal for any person with a liquor license, to sell, serve or supply alcoholic beverages to anyone under 18 years of age. Before the Liquor Licensing Act was enacted in 2011, the minimum age to sell, serve and supply alcoholic beverages was 14 years.[27]

 Zimbabwe
None[28]
16 [28]
It is illegal for any person to sell, lend, give, supply, deliver or offer alcoholic beverages to any child under the age of 16 years, except upon production of a written order signed by the parent or guardian of the child known to such person. The police has the duty to seize any alcoholice beverage in the possession of a child under the age of 16 years without a written consent of the parents or legal guardian.

tag: table

text: Americas[edit]

text: The minimum age to purchase and consume varies, but the most common age is 18 years. However in North America the age limits varies between 18 and 21 years of age. Throughout the United States the minimum legal age to purchase any alcoholic beverage from a shop, supermarket, liquor store, bar, club or any other licensed premises is 21 years of age. In Canada each province can decide which minimum age limit is to be set to buy or consume alcohol. Most provinces have a minimum age of 19 years, while Alberta, Manitoba and Quebec have set a minimum age of 18 years. In South America all countries have set a minimum purchase age of 18 years, except for Guyana where minors aged 16 or 17 may consume a glass of beer, wine or cider in a restaurant provided they buy a meal, and Paraguay the only country with a minimum legal pruchase and drinking age of 20 years.

text:
Country
State/Region/Province
De jure
Notes

Drinking age
Purchase age

 Anguilla
None[29]
18 [29]
It is illegal to sell or serve alcoholic drinks to anyone under the age of 18 years. Violating the regulation is punished with a $9.600 fine.

 Antigua and Barbuda
None
16[30]
The sale and distribution of alcohol to a person under 16 years of age is illegal.

 Argentina
18[31]

 Bahamas
18[32]
It is illegal for any adult to sell, serve or supply any alcoholic beverage to a child (defined as anyone under the age of 18 years). The law provides a exception to treat a illness in urgent cases or upon order by a medical doctor.

 Barbados
None
16[33]
It is illegal to sell or serve any alcoholic beverage to anyone under the age of 16 years. The President of the Barbados Road Safety Association is trying to raise the drinking age to 18 years due to the fact that the law is often violated.[33]

 Belize
18[34]
Drinking age is rarely enforced. IDs are almost never requested.

 Bermuda
18[35]
It is illegal to sell or serve any alcoholic beverage to a child under the age of 18 years.

 Bolivia
None[36]
18 [36]
It is illegal to sell or serve alcoholic beverages to minors under the age of 18 years. Every sold alcoholic beverage has to have a warning message on the bottle or container reading: “VENTA PROHIBIDA A MENORES DE 18 AÑOS DE EDAD” (Sale prohibited to (anyone) under 18 years of age) and “EL CONSUMO EXCESIVO DE ALCOHOL ES DAÑINO PARA LA SALUD” (Excessive alcohol consumption is harmful to (ones) health).

 Brazil
None[37]
18 [37]
It is illegal to sell, serve or supply any alcoholic beverage to a person under 18 years of age. The presidential law enacted on March 17 2015 made any violation of the law a criminal offence. Any adult person selling, serving, giving or supplying alcoholic beverages to a minor is punished with imprisonment of 2 to 4 years, a fine of R$ 3.000 to R$ 10.000 and a ban to operate any business selling or serving alcohol.

 British Virgin Islands
16[34]
It is illegal to sell or to supply alcohol to anyone under the age of 16.

 Canada
 Alberta
 Manitoba
 Quebec
18[38][39][40]
In Alberta no person may give or sell or permit any person to give or sell liquor to a minor in licensed premises.[38] In Manitoba a person must not give, sell or otherwise supply liquor to a minor. the law provides exceptions for a doctor, dentist, pharmacist or other health care professional for medical purposes; for sacramental purposes and by the parent, guardian, spouse or common-law partner, if it is given or supplied in a residence.[39] In Quebec the law probits the sale of alcoholic beverages to a minor under the age of 18 years.[40]

 Ontario
 Saskatchewan
 British Columbia
 Newfoundland and Labrador
 Nova Scotia
 New Brunswick
 Prince Edward Island
 Northwest Territories
 Yukon
 Nunavut
19

 Cayman Islands
18[41]
It is prohibited to sell, serve or supply alcoholic beverages to anyone under the age of 18 years. It is also illegal for any minor to buy, attempt to buy or consume alcoholic beverages. Violation of the lawis punished with a fine of five thousand dollars, and the court may, if the offence was committed by the licensee, order that the licensee shall forfeit his licence and that no licence may be issued to that person for a period not exceeding ten years from the date of his conviction.

 Chile
18[42]
The minimum age is 18 to enter an enclosure that sells alcoholic beverages. Selling alcohol to a minor may incur a fine. One must provide identification upon request. Residents of Chile over the age of 18 must carry their Chilean identification card issued by the Civil Registry and Identification Service at all times.[43]

 Colombia
None
18[44]
The law prohibits the sale of aclohol to a minor (anyone under the age of 18 years). It is not illegal for minors to buy, attempt to buy or consume alcohol.[44]

 Costa Rica
None
18[45]
The law prohibits the sale of aclohol to a minor (anyone under the age of 18 years). Selling alcohol to a minor will be punished with a fine equivalent to ten basic salaries. Whoever permits minors to maintain in any establishment which main purpose is to sell alcoholic beverages, will be sanctioned with a fine equivalent to five salaries. It is not illegal for minors to buy, attempt to buy or consume alcohol.[45]

 Cuba
None
16[46]
The penal code prohibits any adult to induce any young person under the age of 16 years, to habitually consume alcoholic beverages. However this means that defacto anyone selling, serving or supplying alcohol should check if the buyer has attained the age of 16 years. In most cases this law is not strictly enforced.[46][47]

 Dominican Republic
None
18[48]

 Ecuador
None
18[49]
It is illegal to sell alcohol beverages to a minor under the age of 18 years of age. The law obligates establishments to place a visible notice at the point of sale and to check identification to enforce the law. However it is not illegal for minors to buy, attempt to buy or consume alcohol.[49]

 El Salvador
None
18[50]
It is strictly prohibited to sell or serve alcoholic beverages to a minor under the age of 18 years. Violation of the law is punished with ¢ 25,000.00 and if convicted once more the license will be suspended for a period of six months. It is legal for minors to buy, attempt to buy and consume alcohol.[50]

 Falkland Islands
18[51]
It is illegal for any adult to sell, give or provide alcohol to a minor under the age of 18 years in any public place or licensed premises. Parents may permit their children to consume alcohol on private premises. Minors consuming alcohol in public are committing a criminal offence. The law provides exceptions for the consumption of alcohol by minors for prescription of or at the direction of a government medical officer or in the course of the administration of Holy Communion according to the rites of any Christian denomination.[51]

 Grenada
18[52]
It is illegal to sell, serve or supply any alcoholic drink to a minor under 18 years of age. Minors under 18 years are prohibited by law, to consume alcoholic beverages in public.[52]

 Guatemala
18[53]
It is illegal to sell, serve or supply any alcoholic drink to a minor under 18 years of age. Minors under 18 years are prohibited by law, to consume alcoholic beverages in public.[53]

 Guyana
18/16 for beer, wine and cider with meal[54]
It is illegal to sell or serve alcool to a person under 18 years of age. The law provides a exception for minors aged 16 and 17, if they consume a glass of beer, wine oder cider with a meal in a restaurant. Otherwise attempting to buy alcohol or buying alcohol as a minor is a offence.[54]

 Haiti
None
18[55]
It is illegal to sell or serve alcohol to minors from May 17 2017. Vendors are required to check identification.

 Honduras
18[42]

 Jamaica
None
18[56]
It is illegal to sell or serve any alcoholic beverage to a child (which is defined as anyone under the age of 18 years).[56]

 Mexico
18[42]
The minimum age to buy and consume alcoholic beverages is regulated by each state of Mexico. But all states have set a minimum age of 18 years, and in no state it is illegal for minors to buy and consume alcohol.

 Nicaragua
None
14 (restaurant)
18 (bars, clubs, markets, supermarkets, sports and recreation centers)[57]
The law from 1980 prohibits the sale of acloholic beverages to minors under the age of 18 years. Ever point of sale or establishment serving alcohol, is required to post a notice stating that the sale of alcohol to minors under 18 years of age is illegal. However the law permits children as young as 14 to purchase and consume alcohol in a restaurant without further restrictions.[57]

 Panama
None
18[58]

 Paraguay
20[59]
According to Art. 1° of the law to "ban on the sale of alcoholic beverages to minors", it is illegal to serve or sell alcohol or to allow the consumption by minors under 20 years of age. Furthermore, under Art 2° all public establishments selling alcohol must display a clearly legible notice in the sales area with the following text: "ESTA PROHIBIDA LA VENTA DE BEBIDAS ALCOHÓLICAS A MENORES DE VEINTE AÑOS DE EDAD" (It is illegal (prohibited) to sell alcoholic beverages to minors under 20 years of age)

 Peru
None
18[60]

 Puerto Rico
18

 Trinidad and Tobago
None
18[61]
It is illegal to sell, serve or supply alcoholiv beverages to child under the age of 18 years. It is also illegal for an adult to send a child to buy alcohol on behalf. It is not illegal for children to buy or consume alcohol.[61]

 Turks and Caicos Islands
None
18[62]
It is illegal to serve or sell liquor to a young person under the age of eighteen years. Minors under the age of sixteen years may not present in a licensed premises mainly serving and selling alcoholic beverages.[62]

 United States
(50 states and integral territories)
Varies by jurisdiction[42]
21[42]
The National Minimum Drinking Age Act of 1984 withholds revenue from states that allow the purchase of alcohol by anyone under the age of 21. Prior to the effective date of that Act, the drinking age varied from state to state. Some states do not allow those under the legal drinking age to be present in liquor stores or in bars (usually, the difference between a bar and a restaurant is that food is served only in the latter). Contrary to popular belief, since the act went into law, only a few states prohibit minors and young adults from consuming alcohol in private settings. As of January 1, 2010, 15 states and the District of Columbia ban underage consumption outright, 17 states do not ban underage consumption, and the remaining 18 states have family member or location exceptions to their underage consumption laws.
Federal law explicitly provides for religious exceptions. As of 2005, 31 states have family member or location exceptions to their underage possession laws. However, non-alcoholic beer in many (but not all) states, such as Idaho, Texas, and Maryland, is considered legal for those under the age of 21.[63]
By a judge's ruling, South Carolina appears to allow the possession and consumption of alcohol by adults 18 to 20 years of age, but a circuit court judge has said otherwise.[64]
The states of Washington and Wisconsin allows the consumption of alcohol in the presence of parents.
Some U.S. states have legislation that make providing to and possession of alcohol by persons under twenty-one a gross misdemeanor with a potential penalty of a $5,000 fine or up to year in jail.[65]
See also: Minor in Possession and List of alcohol laws of the United States

 United States Virgin Islands
18[66]

 Uruguay
None
18[67]
Only selling alcohol to minors under the age of 18 is prohibited, consumption and purchase by minors is not illegal.

 Venezuela
None
18[68]
Only selling alcohol to minors under the age of 18 is prohibited, consumption and purchase by minors is not illegal.[68]

text: Asia[edit]

text:
Country
State/Region/Province
De jure
Notes

Drinking age
Purchase age

 Afghanistan
Illegal[69]

 Bangladesh
(Illegal for Muslims.)[70]
Alcohol will be sold to foreigners in certain locations, albeit clandestinely.[citation needed]

 Bhutan
18[71]

 Brunei
17 with restrictions, unless Muslim[42]
Non-Muslims over 17 years of age are allowed to import alcohol not to exceed maximum total volume 2 liters of liquor and 12 cans of beer at 330 ml for personal use, once in 48 hours. This alcohol must be “stored and consumed at the place of residence of the importer” and is “not to be given, transferred or sold to another person.”.[42]

 Cambodia
None[72]

 China
18[42]
Introduced in January 2006.[73]

 Hong Kong
18[74]
The regulation is only applicable to restaurants, bars and clubs, where a liquor license is required. Private drinking is also not regulated.[citation needed]

 India
18–25 (varies by jurisdiction)[42]

Main article: Alcohol laws of India
Consumption of alcohol is illegal in the states of Bihar, Gujarat and Nagaland.[75]

 Indonesia
21[76]

 Iran
Illegal [42]
There is a ban on alcohol, but religious minorities may purchase small amounts from shops owned by the same religious minority.[77]

 Iraq
18[78]

 Israel
None
18[42]
Israel law prohibits selling or serving alcohol to minors, but it does not prohibit minors to drink, although the police may confiscate alcoholic drinks consumed by minors in public.[citation needed]

 Japan
20[42]

 Jordan
18[79]

 Kazakhstan
21[80]

 Kuwait
Illegal[81]

 Kyrgyzstan
18[42]

 Lebanon
18[42]
Often unenforced and according to a global school health study, 40% of minors over 13 drink alcohol and up to 25% buy it from stores.[82]

 Macau
None[citation needed]

 Malaysia
21
Increased from 18 to 21 in December 2017.[83]

 Maldives
Illegal except for tourists, 18[citation needed]
Sale of alcohol is limited to tourist resorts. It is illegal to sell alcohol to local Maldivians[84]

 Mongolia
18[85]

 Myanmar
None
18[86]

   Nepal
18
The legal age for consumption of alcohol in Nepal is 18. However, there are exceptions to underage consumption for purposes of religious ceremonies.[citation needed]

 North Korea
18[87]

 Oman
21
Residents need personal liquor licenses to consume alcohol in their private residences.[88]

 Pakistan
Illegal [42]
Non-Muslim citizens may possess alcohol to be used in accordance with religious ceremonies[42]

 Palestinian Authority
16[citation needed]
Legal in most cities.[citation needed]

 Philippines
18[89]

 Qatar
19[citation needed]
Muslims are allowed to purchase alcohol, but generally not allowed to consume. Non Muslims are allowed to purchase, and consume alcohol. The only legal distributor of alcohol in the country is the Qatar Distribution Company located in Doha.[citation needed]

 Saudi Arabia
Illegal
Drinking or possessing alcohol is illegal in the Kingdom of Saudi Arabia. Persons who drink or possess alcohol are subject to arrest and trial. Punishments range from heavy fines, lengthy prison terms and whippings.[citation needed]

 Singapore
None (Private places, sometimes with permission from parents/guardian)
18 (Public places e.g. bars and restaurants)
18[42]
For convenience stores, those who pretend to be 18 years and above in a "Challenge 18" scheme will be downgraded to "Challenge 21" scheme, and after which the licences will be revoked once they pretend to be 18 years and above if it is on "Challenge 21".[citation needed]. It is illegal to purchase alcohol in Singapore or consume in a nightclub/allow entry to the nightclub under 18. Home and private drinking of alcohol is allowed, although the safest age could be 6. Parents can try a sip of alcohol at any age.[citation needed]

 South Korea
None
19[90]
The age limit for alcohol is after January 1 of the year one's age turns to 19.[91]

 Sri Lanka
21[42]

 Syria
18[citation needed]

 Taiwan
18[92]

It is illegal for anyone under the age of 18 to consume alcohol.[93]
Parents, guardians, and others taking care of people under 18 shall prohibit underage drinking,[94] or risk administrative fines of 10000 to 50000 new Taiwan dollars when the situations are serious.[95]
One shall not supply alcohol to anyone under the age of 18.[96] A violator shall be administratively fined 3000 to 15000 New Taiwan Dollars.[97]

 Tajikistan
18[42]

 Thailand
20[98]
The Alcoholic Beverage Control Act of 2008 increased the drinking age in Thailand from 18 to 20, private drinking is not regulated in private locations.[98][99]

 Turkmenistan
18[42]

 United Arab Emirates
18–21 (varies by jurisdiction).[100]
Expatriate non-Muslim residents may request a liquor permit to purchase alcoholic beverages, but it is illegal for such holders to provide drinks to others.[101]
The legal age for drinking alcohol is 18 in Abu Dhabi (although a Ministry of Tourism by-law allows hotels to serve alcohol only to those over 21), and 21 in Dubai and the Northern Emirates (except Sharjah, where drinking alcohol is illegal).[100]
It is a punishable offence to drink, or to be under the influence of alcohol, in public.[100]

 Uzbekistan
None
20[42]

 Vietnam
18[42]

 Yemen
Illegal[citation needed]
Exception is in Aden Region where it's legal for 21 and up[citation needed]

text: Europe[edit]

text: Most countries within Europe have set 18 as the minimum age to purchase alcohol. Although Austria, Belgium, Cyprus, Denmark, Germany, Gibraltar, Liechtenstein, Luxembourg, Malta, Serbia and Switzerland (except Ticino) maintain a minimum purchase age below 18 years permitting minors either full or limited access to alcohol. In 2005[102], 2007[103] and recently in 2015[104] the European Union has failed to enact a law forcing member states to raise their purchase age to 18 years. But in the past years several European countries have raised their drinking/purchase age or enacted laws restricting the access to alcohol for minors:

text:
In 2002 the autonomous communities Madrid,[105] Valencia[106] and Catalonia[107] raised their minimum purchase age to 18 years. Previous to 2002 Valencia and Madrid had a minimum purchase age of 16 years, and in Catalonia minors aged 16 or 17 could purchase alcohol up to 23% ABV on and off premises.
In 2004 Denmark[108] raised its off premises purchase age from 15 to 16 years.
In November 2005 Switzerland passed its "Food and Commodities Regulation"[109] (German: Lebensmittel- und Gebrauchsgegenständeverordnung), introducing a ban on alcohol sales to anyone under the age of 16, although the 1980 passed "Alcohol Law"[110] (German: Alkoholgesetz) already required a minimum age of 18 years for the retail sale of distilled spirits. Therefore, it is illegal to sell fermented alcohol (e.g. beer, wine, sparkling wine or cider) to anyone under the age of 16, and any distilled alcoholic beverages to anyone under the age of 18 years. Further the canton of Ticino introduced a contonal law in 1989 banning all alcohol sales to anyone under the age of 18 years.[111]
In 2006 the autonomous communitie Castile and León[112] raised its minimum purchase age from 16 to 18 years.
In late 2006, Gibraltar[113] lawmakers passed the "Children and Young Persons (Alcohol, Tobacco and Gaming) Act 2006", which raised the minimum purchase age from 16 to 18 years. But the new law made an exception: minors aged 16 or 17 can purchase and consume on premises beer, wine or cider under 15% ABV or pre-packed containers of an alcoholic strength not exceeding 5.5% ABV (e.g. alcopops).
In 2009 France[114] raised its minimum purchase age to 18 years, and fines were increased for selling or serving alcohol to a minor (up to 7,500 €). Previous to 2009 the minimum age to purchase any alcohol from off licensed premises was 16 years. In order to purchase alcohol on premises the minimum age was 16 years for low alcoholic beverages such as wine, beer, cider, perry, mead, crème de cassis and juices from fermented fruits or vegetables that contain 1.2 to 3° alcohol, natural sweet wines from controlled cultivation – to purchase or be served stronger alcoholic drinks one had to be 18 years of age.
In October 2009, the government of Malta[115] passed a new law raising its drinking and purchase age from 16 to 17 years.
In 2010 the autonomous community of Galicia raised its minimum purchase age from 16 to 18 years.[116]
In 2011 Denmark[117] passed a new law, raising the minimum age for off-premises sale of alcohol >16.5% ABV to 18 years of age. The age to purchase alcohol <16.5% ABV remaines at 16.
Italy raised its minimum purchase age from 16 to 18 in 2012. Previously Italy did not have a purchase age for off-premises sales, and the minimum age of 16 years for on premises sales was barely enforced. [118]
In 2013 the government of Portugal restricted alcohol sales to young people: distilled spirits can not be sold to anyone under the age of 18, and other alcohol (e.g. beer, wine or cider) can't be sold to anyone under the age of 16. Previously the minimum age for all kinds of alcoholic beverages was 16 years.[119]
As of 1 January 2014, the minimum legal purchase and consumption age was raised from 16 to 18 in the Netherlands. Previously young people over the age of 16 could purchase and consume alcohol <15% ABV, and adults aged 18 and over could purchase alcohol over 15% ABV.[120]
As of March 2015, the autonomous community of Asturias raised its drinking age from 16 to 18 years. Asturias was Spain's last community with a drinking age of 16 years. The new law brings the drinking age into line with the rest of Spain.[121]
As of 1 January 2018, Lithuania raised its minimum drinking age from 18 to 20 years[122]

tag: ul

text:
Country
State/Region/Province
De jure
Notes

Drinking age
Purchase age

 Albania
18[42]

 Armenia
None[123]
18[123]
There are no laws mandating alcohol vendors to ID potential underage drinkers. ID checks are very rarely, if ever, carried out[123]

 Austria
 Burgenland
 Lower Austria
 Vienna
16
[124]

 Carinthia
 Upper Austria
 Salzburg
 Styria
 Tyrol
 Vorarlberg
16 (beer, wine and cider)
18 (distilled beverages)
Carinthia also requires adolescents to maintain a blood alcohol level below 0.05%.[124]

 Azerbaijan
None[125]
18[125]
It is illegal to sell or serve alcohol to a minor under 18 years of age.[125]

 Belarus
None[126]
18[126]
The law prohibits the sale of alcohol to anyone under the age of 18 years. However, the law is rarely enforced.[126]

 Belgium
None[127]
16 (beer, wine and cider)
18 (spirits)[127]
Since 10 January 2010, it is illegal to "sell, serve, or offer" any form of distilled alcohol to those under the age of 18 or any alcoholic drink to those under 16. So fermented drinks like beer or wine are permitted above 16.[127] Previously, it was illegal to sell alcoholic drinks to under-16s, but accompanying adults could buy drinks for them.

 Bosnia and Herzegovina
None[128]
18[128]
Selling alcohol to a minor under the age of 18 years is a offence. The law does not prohibit minors from buying, attempting to buy or consuming alcohol.[128]

 Bulgaria
None[129]
18[129]
By law, it is illegal to serve or sell alcohol to any child under the age of 18. There is no restrictions for minors consuming alcohol.[129]

 Croatia
None[130]
18[130]
It is prohibited to sell or serve alcohol to anyone under 18 years of age. There is no minimum age to buy or consume alcohol by law.[130]

 Cyprus
None[131]
17[131]
It is illegal to sell or serve alcohol to anyone under thhe age of 17 years. There is no minimum age to buy, attempt to buy or consume alcohol in public.[131]

 Czech Republic
None
18[132]
It is illegal to provide alcohol to minors[133] (punishable by fine or up to 1[134] or 2[135] year(s) imprisonment). Consumption itself is not prohibited by law.[136]

 Denmark
None
16 (<16.5% ABV)
18 (≥16.5% ABV)
While there is no age requirement for drinking alcohol in Denmark, there are laws that prevent minors from buying alcohol:

In order to buy alcohol above 1.2% and below 16.5% ABV in stores, one must be 16 years of age.
In order to buy alcohol above 16.5% ABV in stores, one must be 18 years of age.[137]

By tradition, youths are privately allowed to drink alcohol after their confirmation.[138] If a shop or bar fails to ask for an ID card and is identified having sold alcohol to an underage, it is subject to fine. A national ID card, obtained in the local town hall, can serve as age verification.[139] This card is rarely used though since a passport or drivers license is more commonly used.[140]
Both the legal drinking and purchasing age in the Faroe Islands is 18.[citation needed]

 Estonia
18[141]
It is illegal to sell, serve or supply alcoholic beverages to anyone under the age of 18 years. Alcohol found in possession of any child can be confiscated by the police.

 Finland
18 (possession and purchase of 1.2–22% ABV)
20 (for possession and purchase of 23–80% ABV)
18 (for all in bars, clubs and restaurants)[142]
All major grocery chains have implemented a policy to ask for ID if the customer looks under 30.[143] Stores may refuse to sell alcohol if the customer is accompanied by a minor, or if proxy purchasing is suspected. Purchasing alcohol on behalf of a minor is a criminal offence.[142][144]
Police may search minors in public places and confiscate or destroy any alcoholic beverages in their possession. Incidents are reported to the legal guardian and social authorities, who may intervene with child welfare procedures. In addition, those aged 15 or above are subject to a fine.[145]
In private, offering alcohol to a minor is considered a criminal offence if it results in drunkenness and the act can be deemed reprehensible as a whole, considering the minor's age, degree of maturity and other circumstances.[142]

 France
None
18
France has no explicitly stated consumption age,[146] but selling alcohol to a minor (under 18) is illegal[147] and can be fined 7500 euros.[146] This age was raised from 16 to 18 in 2009.[148][149]

 Georgia
None[150]
18[150]
By Georgian law, the sale of alcoholic beverages to anyone under the age of 18 years is prohibited.[150]

 Germany
14(beer, wine and cider if accompanied)
16 (beer, wine and cider)
18 (spirits and aliments containing spirits above negligible amounts)[151]
It is illegal to sell, serve or supply fermented alcoholic beverages (beer, wine, cider and sparkling wine) to anyone under 16 years of age. However this age limit drops down to 14 if a minor is accompanied by his parent or legal guardian. It is generally illegal to serve, sell or supply any beverage containing spirits and aliments containing spirits above negligible amounts, to anyone under the age of 18 years. Violation of the "Protection of Young Persons Act" can be fined up to 50.000€.
See also: Alcohol laws in Germany

 Gibraltar
None[152]
18
16(beer, wine and cider)[152]
It is illegal to sell alcoholic drinks to anyone under the age of 18, other than the following two exceptions. The minimum age to be served in licensed premises is 16 if:[152]

The alcoholic beverage is beer, wine or cider below 15% ABV, or
The alcoholic beverage is served in a bottle, or a pre-packaged container below 5.5% ABV.

 Greece
None[153]
18[153]
In 2008, the consumption of alcoholic beverages was prohibited for minors in public. However, the law does not apply to private events or private premises.[153]

 Hungary
18[42]

 Iceland
None
20[154]
Possession or consumption of alcohol by minors is not an offence, but supplying them with alcohol is.

 Ireland
None (on private residence with permission from parents or guardians)[155]
18[155]
It is illegal for minors to buy alcohol or for a third party to attempt to buy it for minors. It is illegal to purchase alcohol for anybody under the age of consent without permission from their guardians.[156]

 Italy
None [157]
18[158][157]
In 2012 the then Health Minister Renato Balduzzi proposed to raise the age to 18.[157] Selling alcohol to those under the age of 18 in shops carries a fine between €250 and €1000. Serving alcoholic beverages to those under the age of 16 is a criminal offense and is punished with prison up to one year, if the individual is 16 or 17 it will be treated as an offense that is fined between €250 and €1000 (Legge n. 189/2013).

 Kosovo
None[citation needed]

 Latvia
None[159]
18[159]
It is illegal to sell or serve alcoholic beverages to any minor under the age of 18 years. There is no minimum age to consume or possess alcohol.[159]

 Liechtenstein
16 beer, wine and cider
18 spirits and spirit-based beverages[160]
Wine, beer and ciders as well as some other party drinks sometimes without spirits may be purchased by the age of 16. Spirits as well as alcopops may be sold only to people at least 18.[160]

 Lithuania
20[122]
It is illegal to sell, serve or supply acloholic beverages to anyone under the age of 20 years. Minors under the age of 20 are prohibited from consuming alcoholic beverages or from possessing them. The minimum age was raised from 18 to 20 since 2018.[122]

 Luxembourg
None [161]
16[161]
It is illegal to sell or serve alcoholic beverages >1.2% ABV to any person under the age of 16 years. Violation is fined €251 to €1.000.[161]

 Macedonia
18[162]
Must show an ID card upon request. In certain smaller places, such as family-owned convenience stores and street kiosks, there is little to no enforcement on how old or young somebody purchases alcohol. There is little to no enforcement for drinking privately, but drinking in bars may require an ID.

 Malta
17[163]
Must provide identification upon request.

 Moldova
None[164]
18[164]
It is illegal to sell, or serve alcoholic beverages to anyone under the age of 18 years. It is not illegal for minors to buy, attempt to buy or consume alcohol. The minimum purchase age was raised from 16 to 18 in 2012.[165][164]

 Montenegro
18[citation needed]

 Netherlands
18
The legal age for purchasing and consumption of alcoholic beverages was raised from 16 to 18 since 2014. Alcohol is commonly available upon parental permission. Selling alcoholic beverages to people under 18 is illegal, although giving it away in private is not.[citation needed]

 Norway
None[166]
18 (<22%)
20 (≥22% ABV)[42]
Selling alcohol to or buying alcohol for minors is illegal. Minors are defined as under 18 for beer and wine, under 20 for drinks that contain 22% ABV or more. Minors who buy alcohol are not held criminally responsible; instead, the crime lies with those who sold it or obtained it for them.
Alcohol with more than 60% ABV is generally not sold in Norway, although exceptions may be made by the government for specific products.[167]
Alcohol possessed by minors may be confiscated as evidence. Drinking in public is prohibited, though this is rarely enforced in recreational areas.[168]

 Poland
None[169]
18[169]
Article 15 of The Act on Upbringing in Sobriety and Counteracting Alcoholism[170] clearly states that buyers or persons being served must be at least 18 and prove it with ID if they look like they may not be at least that age. There is no mention of consumption age in this or any other act in Poland. Drinking on streets, town squares, and in parks is illegal regardless of age.

 Portugal
None[171]
18[171]

 Romania
None
18[172]
According to law 61/1991 updated in 2008, paragraphs 21-25, it is illegal to serve or sell alcohol to minors.

 Russia
None
18[173]
There is no law or regulation in Russia that prohibits minors from consuming alcohol, but selling alcohol to minors is prohibited by federal and additional regional laws.

 Serbia
None
16[174]

 Slovakia
18[175]

 Slovenia
None
18[176]
There is no law regulating the possession and consumption, but it is illegal to sell or offer alcohol of any kind to minors.

 Spain
18
Asturias was the last autonomous community in Spain where the drinking age was increased to 18 (previously 16) on 1 May 2015.[177]

 Sweden

None

None (less than 2.25% ABV)
18 (bars and restaurants)
18 (2.25%–3.5% ABV in food shops)
20 (Systembolaget shops)[178],

See also: Alcohol in Sweden
Many clubs choose to have higher age limits than 18, commonly 20 or 23. It is legal to drink below 18, but it is illegal to sell, lend or give alcohol to someone under that age and the police can seize alcohol from them, apart from being served alcohol supervised in private "in moderation". It is legal to serve an underage person alcohol in a private place.[179] The reason for lower limit in bars than in Systembolaget shops is that bartenders have a legal responsibility for how drunk a guest gets.

  Switzerland
  Switzerland (federal law)
None
(See notes)
16 (fermented alcoholic drinks with less than 15% ABV and natural wines with less than 18% ABV)[180]
18 (spirits) [181]
Whoever offers or supplies alcoholic beverages to a child under the age of 16 years in an amount which is harmful to one's health is punished with imprisonment up to 3 years or a fine.[182] Whoever sells or supplies spirits to a person under the age of 18 years is punished with a fine up to 10.000 CHF.[183]

 Ticino
18
The canton Ticino prohibits selling and consumption of any type of alcohol by minors under the age of 18. Some shops and supermarkets may not sell alcohol to minors under the age of 18.[184]

 Turkey
18[42]

See also: Alcohol laws of Turkey

 Ukraine
18[42]

 United Kingdom
 England
 Wales
18[185]
16 (beer, wine or cider with meal)[185]
5 (private)[186]
None (under medical supervision, or in an emergency)[186]
Legislation in  England and  Wales:

It is illegal to sell, serve, offer or consume alcoholic beverages on licensed premises under the age of 18, other than the following two exceptions:[185]

Minors aged 16 or 17 may consume wine, beer or cider on licensed premises when ordered with a meal, and accompanied by an adult.[185]
It is legal to sell liqueur confectionery to someone of any age.

It is illegal to permit minors under the age of 5 to consume alcoholic beverages unless under medical supervision or in an emergency.[186]
Persons over 17 are entitled to their own duty free allowance, which includes alcohol. [187]

 Scotland
18
16 (beer, wine or cider on licensed premises with meal)[188]
None (private)
Legislation in  Scotland:

It is illegal to sell, serve, offer or consume alcoholic beverages in public under the age of 18, other than the following two exceptions:[189]

Minors aged 16 or 17 may consume wine, beer or cider on licensed premises when ordered with a meal.[189]
It is legal to sell liqueur confectionery to someone of any age.

Persons over 17 are entitled to their own duty free allowance, which includes alcohol. [187]

 Northern Ireland
18
Legislation in Northern Ireland:
It is illegal to sell, serve, offer or consume alcoholic beverages in public under the age of 18.

 United Kingdom
Challenge 21 and Challenge 25 (applies to all of the  United Kingdom)
Under the BBPA's Challenge 21 and Challenge 25 schemes, customers attempting to buy alcoholic beverages are asked to prove their age if in the retailer's opinion they look under 21[190] (or optionally 25) even though the law states they must be a minimum of 18. Many supermarket and off-licence chains display Challenge 21 (or Challenge 25) notices stating that they will not serve persons who look under 21 (or 25) without ID.

text: Oceania[edit]

text:
Country
State/Region/Province
De jure
Notes

Drinking age
Purchase age

 American Samoa
21[191]

 Australia
18[42][192]

Main article: Alcohol laws of Australia
Varies by state. Some states restrict possession and consumption to over 18, all states restrict purchasing to over 18. In some states, minors may consume alcohol in a private residence with parental permission.[193]

 Fiji
18[194]
The drinking age was 21 from 2006 to 2009 but was lowered to 18 in 2009.[194]

 Guam
21[195]

 Micronesia, Federated States of
18[196]

 New Zealand
None
18[197]
Minimum age applies for beverages with 1.15% ABV or over; no restrictions on beverages less than 1.15% ABV.[198]
Persons under 18 may drink outside private residences or private functions if accompanied by their parent or legal guardian. Alcohol may be supplied to minors only by, or with express consent from, their parent or legal guardian.[199]

 Northern Mariana Islands
21[200]

 Palau
21[201]
It is illegal to sell or serve any alcoholic beverage to a person under 21 years of age. Minors may access a bar or licensed premises only if accompanied by a parent or legal guardian. Minors buying, consuming or attempting to buy alcohol are commiting a offence. The law provides a exception for the consumption of alcohol by minors as part of a religiously recognized ceremony.[201]

 Papua New Guinea
18[202]
It is illegal for a minor to purchase, consume or attempt to purchase alcoholic beverages. Any licence holder has to ensure that the customer who he sells or serves alcohol to, is at least 18 years of age. Violation of this law is fined.[202]

 Samoa
21[203]
Selling or serving alcohol to a person under the age of twenty-one years is punished with three hundred dollars or imprisonment for nine months or both, a fine and imprisonment.[204]

 Solomon Islands
None[204]
21[204]
Selling or serving alcohol to a person under the age of twenty-one years is punished with three hundred dollars or imprisonment for nine months or both, a fine and imprisonment.[204]

 Tokelau
18[205]

 Tonga
18[206]
Selling, serving or supplying alcohol to a minor is illegal. It is also illegal for minors to buy, attempt to buy or consume alcohol in any public place and any violation of this law is fined up to $1,000.[206]

 Vanuatu
18[207]
It is unlawful to sell, serve or supply alcohol to any person under the age of 18 years. Violation of the law is fined up to VT 25,000 or by a term of imprisonment not exceeding 3 months, or by both, fine and imprisonment. Any minor under the age of 18 years, beeing found in possession or consumption of alcohol is fined up to VT 10,000.[207]


document_title: Infection

question_text: the person to whom the infectious agent is passed is

question_tokens: the person to whom the infectious agent is passed is

text: Infection

text: Classification[edit]

text: Subclinical versus clinical (latent versus apparent)[edit]

text: Symptomatic infections are apparent and clinical, whereas an infection that is active but does not produce noticeable symptoms may be called inapparent, silent, subclinical, or occult. An infection that is inactive or dormant is called a latent infection.[6] An example of a latent bacterial infection is latent tuberculosis. Some viral infections can also be latent, examples of latent viral infections are any of those from the Herpesviridae family.

text: The word infection can denote any presence of a particular pathogen at all (no matter how little) but also is often used in a sense implying a clinically apparent infection (in other words, a case of infectious disease).[7] This fact occasionally creates some ambiguity or prompts some usage discussion. To get around the usage annoyance, it is common for health professionals to speak of colonization (rather than infection) when they mean that some of the pathogens are present but that no clinically apparent infection (no disease) is present.

text: A short-term infection is an acute infection. A long-term infection is a chronic infection. Infections can be further classified by causative agent (bacterial, viral, fungal, parasitic), and by the presence or absence of systemic symptoms (sepsis).

text: Primary versus opportunistic[edit]

text: Among the many varieties of microorganisms, relatively few cause disease in otherwise healthy individuals.[8] Infectious disease results from the interplay between those few pathogens and the defenses of the hosts they infect. The appearance and severity of disease resulting from any pathogen, depends upon the ability of that pathogen to damage the host as well as the ability of the host to resist the pathogen. However a host's immune system can also cause damage to the host itself in an attempt to control the infection. Clinicians therefore classify infectious microorganisms or microbes according to the status of host defenses - either as primary pathogens or as opportunistic pathogens:

text: Infectious or not[edit]

text: One way of proving that a given disease is "infectious", is to satisfy Koch's postulates (first proposed by Robert Koch), which demands that the infectious agent be identified only in patients and not in healthy controls, and that patients who contract the agent also develop the disease. These postulates were first used in the discovery that Mycobacteria species cause tuberculosis. Koch's postulates can not be applied ethically for many human diseases because they require experimental infection of a healthy individual with a pathogen produced as a pure culture. Often, even clearly infectious diseases do not meet the infectious criteria. For example, Treponema pallidum, the causative spirochete of syphilis, cannot be cultured in vitro – however the organism can be cultured in rabbit testes. It is less clear that a pure culture comes from an animal source serving as host than it is when derived from microbes derived from plate culture. Epidemiology is another important tool used to study disease in a population. For infectious diseases it helps to determine if a disease outbreak is sporadic (occasional occurrence), endemic (regular cases often occurring in a region), epidemic (an unusually high number of cases in a region), or pandemic (a global epidemic).

text: Contagiousness[edit]

text: Infectious diseases are sometimes called contagious disease when they are easily transmitted by contact with an ill person or their secretions (e.g., influenza). Thus, a contagious disease is a subset of infectious disease that is especially infective or easily transmitted. Other types of infectious/transmissible/communicable diseases with more specialized routes of infection, such as vector transmission or sexual transmission, are usually not regarded as "contagious", and often do not require medical isolation (sometimes loosely called quarantine) of victims. However, this specialized connotation of the word "contagious" and "contagious disease" (easy transmissibility) is not always respected in popular use. Infectious diseases are commonly transmitted from person to person through direct contact. The types of contact are through person to person and droplet spread. Indirect contact such as airborne transmission, contaminated objects, food and drinking water, animal person contact, animal reservoirs, insect bites, and environmental reservoirs are another way infectious diseases are transmitted,[10]

text: By anatomic location[edit]

text: Infections can be classified by the anatomic location or organ system infected, including:

text:
Urinary tract infection
Skin infection
Respiratory tract infection
Odontogenic infection (an infection that originates within a tooth or in the closely surrounding tissues)
Vaginal infections
Intra-amniotic infection

text: In addition, locations of inflammation where infection is the most common cause include pneumonia, meningitis and salpingitis.

text: Signs and symptoms[edit]

text: The symptoms of an infection depend on the type of disease. Some signs of infection affect the whole body generally, such as fatigue, loss of appetite, weight loss, fevers, night sweats, chills, aches and pains. Others are specific to individual body parts, such as skin rashes, coughing, or a runny nose.

text: In certain cases, infectious diseases may be asymptomatic for much or even all of their course in a given host. In the latter case, the disease may only be defined as a "disease" (which by definition means an illness) in hosts who secondarily become ill after contact with an asymptomatic carrier. An infection is not synonymous with an infectious disease, as some infections do not cause illness in a host.[9]

text: Bacterial or viral[edit]

text: Bacterial and viral infections can both cause the same kinds of symptoms. It can be difficult to distinguish which is the cause of a specific infection.[11] It's important to distinguish, because viral infections cannot be cured by antibiotics.[12]

text:
Comparison of viral and bacterial infection

Characteristic
Viral infection
Bacterial infection

Typical symptoms
In general, viral infections are systemic. This means they involve many different parts of the body or more than one body system at the same time; i.e. a runny nose, sinus congestion, cough, body aches etc. They can be local at times as in viral conjunctivitis or "pink eye" and herpes. Only a few viral infections are painful, like herpes. The pain of viral infections is often described as itchy or burning.[11]
The classic symptoms of a bacterial infection are localized redness, heat, swelling and pain. One of the hallmarks of a bacterial infection is local pain, pain that is in a specific part of the body. For example, if a cut occurs and is infected with bacteria, pain occurs at the site of the infection. Bacterial throat pain is often characterized by more pain on one side of the throat. An ear infection is more likely to be diagnosed as bacterial if the pain occurs in only one ear.[11] A cut that produces pus and milky-colored liquid is most likely infected.[clarification needed][13]

Cause
Pathogenic viruses
Pathogenic bacteria

text: Pathophysiology[edit]

text: There is a general chain of events that applies to infections.[14] The chain of events involves several steps—which include the infectious agent, reservoir, entering a susceptible host, exit and transmission to new hosts. Each of the links must be present in a chronological order for an infection to develop. Understanding these steps helps health care workers target the infection and prevent it from occurring in the first place.[15]

text: Colonization[edit]

text: Infection begins when an organism successfully enters the body, grows and multiplies. This is referred to as colonization. Most humans are not easily infected. Those who are weak, sick, malnourished, have cancer or are diabetic have increased susceptibility to chronic or persistent infections. Individuals who have a suppressed immune system are particularly susceptible to opportunistic infections. Entrance to the host at host-pathogen interface, generally occurs through the mucosa in orifices like the oral cavity, nose, eyes, genitalia, anus, or the microbe can enter through open wounds. While a few organisms can grow at the initial site of entry, many migrate and cause systemic infection in different organs. Some pathogens grow within the host cells (intracellular) whereas others grow freely in bodily fluids.

text: Wound colonization refers to nonreplicating microorganisms within the wound, while in infected wounds, replicating organisms exist and tissue is injured. All multicellular organisms are colonized to some degree by extrinsic organisms, and the vast majority of these exist in either a mutualistic or commensal relationship with the host. An example of the former is the anaerobic bacteria species, which colonizes the mammalian colon, and an example of the latter is various species of staphylococcus that exist on human skin. Neither of these colonizations are considered infections. The difference between an infection and a colonization is often only a matter of circumstance. Non-pathogenic organisms can become pathogenic given specific conditions, and even the most virulent organism requires certain circumstances to cause a compromising infection. Some colonizing bacteria, such as Corynebacteria sp. and viridans streptococci, prevent the adhesion and colonization of pathogenic bacteria and thus have a symbiotic relationship with the host, preventing infection and speeding wound healing.

text: The variables involved in the outcome of a host becoming inoculated by a pathogen and the ultimate outcome include:

text:
the route of entry of the pathogen and the access to host regions that it gains
the intrinsic virulence of the particular organism
the quantity or load of the initial inoculant
the immune status of the host being colonized

text: As an example, several staphylococcal species remain harmless on the skin, but, when present in a normally sterile space, such as in the capsule of a joint or the peritoneum, multiply without resistance and cause harm.

text: An interesting fact that gas chromatography–mass spectrometry, 16S ribosomal RNA analysis, omics, and other advanced technologies have made more apparent to humans in recent decades is that microbial colonization is very common even in environments that humans think of as being nearly sterile. Because it is normal to have bacterial colonization, it is difficult to know which chronic wounds can be classified as infected and how much risk of progression exists. Despite the huge number of wounds seen in clinical practice, there are limited quality data for evaluated symptoms and signs. A review of chronic wounds in the Journal of the American Medical Association's "Rational Clinical Examination Series" quantified the importance of increased pain as an indicator of infection.[19] The review showed that the most useful finding is an increase in the level of pain [likelihood ratio (LR) range, 11–20] makes infection much more likely, but the absence of pain (negative likelihood ratio range, 0.64–0.88) does not rule out infection (summary LR 0.64–0.88).

text: Disease[edit]

text: Disease can arise if the host's protective immune mechanisms are compromised and the organism inflicts damage on the host. Microorganisms can cause tissue damage by releasing a variety of toxins or destructive enzymes. For example, Clostridium tetani releases a toxin that paralyzes muscles, and staphylococcus releases toxins that produce shock and sepsis. Not all infectious agents cause disease in all hosts. For example, less than 5% of individuals infected with polio develop disease.[20] On the other hand, some infectious agents are highly virulent. The prion causing mad cow disease and Creutzfeldt–Jakob disease invariably kills all animals and people that are infected.

text: Persistent infections occur because the body is unable to clear the organism after the initial infection. Persistent infections are characterized by the continual presence of the infectious organism, often as latent infection with occasional recurrent relapses of active infection. There are some viruses that can maintain a persistent infection by infecting different cells of the body. Some viruses once acquired never leave the body. A typical example is the herpes virus, which tends to hide in nerves and become reactivated when specific circumstances arise.

text: Persistent infections cause millions of deaths globally each year.[21] Chronic infections by parasites account for a high morbidity and mortality in many underdeveloped countries.

text: Transmission[edit]

text: For infecting organisms to survive and repeat the infection cycle in other hosts, they (or their progeny) must leave an existing reservoir and cause infection elsewhere. Infection transmission can take place via many potential routes:

text:
Droplet contact, also known as the respiratory route, and the resultant infection can be termed airborne disease. If an infected person coughs or sneezes on another person the microorganisms, suspended in warm, moist droplets, may enter the body through the nose, mouth or eye surfaces.
Fecal-oral transmission, wherein foodstuffs or water become contaminated (by people not washing their hands before preparing food, or untreated sewage being released into a drinking water supply) and the people who eat and drink them become infected. Common fecal-oral transmitted pathogens include Vibrio cholerae, Giardia species, rotaviruses, Entameba histolytica, Escherichia coli, and tape worms.[22] Most of these pathogens cause gastroenteritis.
Sexual transmission, with the resulting disease being called sexually transmitted disease
Oral transmission, Diseases that are transmitted primarily by oral means may be caught through direct oral contact such as kissing, or by indirect contact such as by sharing a drinking glass or a cigarette.
Transmission by direct contact, Some diseases that are transmissible by direct contact include athlete's foot, impetigo and warts
Vehicle Transmission, transmission by an inanimate reservoir (food, water, soil).[23]
Vertical transmission, directly from the mother to an embryo, fetus or baby during pregnancy or childbirth. It can occur when the mother gets an infection as an intercurrent disease in pregnancy.
Iatrogenic transmission, due to medical procedures such as injection or transplantation of infected material.

text: Vector-borne transmission, transmitted by a vector, which is an organism that does not cause disease itself but that transmits infection by conveying pathogens from one host to another.[24]

text: The relationship between virulence versus transmissibility is complex; if a disease is rapidly fatal, the host may die before the microbe can be passed along to another host.

text: Diagnosis[edit]

text: Diagnosis of infectious disease sometimes involves identifying an infectious agent either directly or indirectly. In practice most minor infectious diseases such as warts, cutaneous abscesses, respiratory system infections and diarrheal diseases are diagnosed by their clinical presentation and treated without knowledge of the specific causative agent. Conclusions about the cause of the disease are based upon the likelihood that a patient came in contact with a particular agent, the presence of a microbe in a community, and other epidemiological considerations. Given sufficient effort, all known infectious agents can be specifically identified. The benefits of identification, however, are often greatly outweighed by the cost, as often there is no specific treatment, the cause is obvious, or the outcome of an infection is benign.

text: Diagnosis of infectious disease is nearly always initiated by medical history and physical examination. More detailed identification techniques involve the culture of infectious agents isolated from a patient. Culture allows identification of infectious organisms by examining their microscopic features, by detecting the presence of substances produced by pathogens, and by directly identifying an organism by its genotype. Other techniques (such as X-rays, CAT scans, PET scans or NMR) are used to produce images of internal abnormalities resulting from the growth of an infectious agent. The images are useful in detection of, for example, a bone abscess or a spongiform encephalopathy produced by a prion.

text: Symptomatic diagnostics[edit]

text: The diagnosis is aided by the presenting symptoms in any individual with an infectious disease, yet it usually needs additional diagnostic techniques to confirm the suspicion. Some signs are specifically characteristic and indicative of a disease and are called pathognomonic signs; but these are rare. Not all infections are symptomatic.[25]

text: In children the presence of cyanosis, rapid breathing, poor peripheral perfusion, or a petechial rash increases the risk of a serious infection by greater than 5 fold.[26] Other important indicators include parental concern, clinical instinct, and temperature greater than 40 °C.[26]

text: Microbial culture[edit]

text: Microbiological culture is a principal tool used to diagnose infectious disease. In a microbial culture, a growth medium is provided for a specific agent. A sample taken from potentially diseased tissue or fluid is then tested for the presence of an infectious agent able to grow within that medium. Most pathogenic bacteria are easily grown on nutrient agar, a form of solid medium that supplies carbohydrates and proteins necessary for growth of a bacterium, along with copious amounts of water. A single bacterium will grow into a visible mound on the surface of the plate called a colony, which may be separated from other colonies or melded together into a "lawn". The size, color, shape and form of a colony is characteristic of the bacterial species, its specific genetic makeup (its strain), and the environment that supports its growth. Other ingredients are often added to the plate to aid in identification. Plates may contain substances that permit the growth of some bacteria and not others, or that change color in response to certain bacteria and not others. Bacteriological plates such as these are commonly used in the clinical identification of infectious bacterium. Microbial culture may also be used in the identification of viruses: the medium in this case being cells grown in culture that the virus can infect, and then alter or kill. In the case of viral identification, a region of dead cells results from viral growth, and is called a "plaque". Eukaryotic parasites may also be grown in culture as a means of identifying a particular agent.

text: In the absence of suitable plate culture techniques, some microbes require culture within live animals. Bacteria such as Mycobacterium leprae and Treponema pallidum can be grown in animals, although serological and microscopic techniques make the use of live animals unnecessary. Viruses are also usually identified using alternatives to growth in culture or animals. Some viruses may be grown in embryonated eggs. Another useful identification method is Xenodiagnosis, or the use of a vector to support the growth of an infectious agent. Chagas disease is the most significant example, because it is difficult to directly demonstrate the presence of the causative agent, Trypanosoma cruzi in a patient, which therefore makes it difficult to definitively make a diagnosis. In this case, xenodiagnosis involves the use of the vector of the Chagas agent T. cruzi, an uninfected triatomine bug, which takes a blood meal from a person suspected of having been infected. The bug is later inspected for growth of T. cruzi within its gut.

text: Microscopy[edit]

text: Another principal tool in the diagnosis of infectious disease is microscopy. Virtually all of the culture techniques discussed above rely, at some point, on microscopic examination for definitive identification of the infectious agent. Microscopy may be carried out with simple instruments, such as the compound light microscope, or with instruments as complex as an electron microscope. Samples obtained from patients may be viewed directly under the light microscope, and can often rapidly lead to identification. Microscopy is often also used in conjunction with biochemical staining techniques, and can be made exquisitely specific when used in combination with antibody based techniques. For example, the use of antibodies made artificially fluorescent (fluorescently labeled antibodies) can be directed to bind to and identify a specific antigens present on a pathogen. A fluorescence microscope is then used to detect fluorescently labeled antibodies bound to internalized antigens within clinical samples or cultured cells. This technique is especially useful in the diagnosis of viral diseases, where the light microscope is incapable of identifying a virus directly.

text: Other microscopic procedures may also aid in identifying infectious agents. Almost all cells readily stain with a number of basic dyes due to the electrostatic attraction between negatively charged cellular molecules and the positive charge on the dye. A cell is normally transparent under a microscope, and using a stain increases the contrast of a cell with its background. Staining a cell with a dye such as Giemsa stain or crystal violet allows a microscopist to describe its size, shape, internal and external components and its associations with other cells. The response of bacteria to different staining procedures is used in the taxonomic classification of microbes as well. Two methods, the Gram stain and the acid-fast stain, are the standard approaches used to classify bacteria and to diagnosis of disease. The Gram stain identifies the bacterial groups Firmicutes and Actinobacteria, both of which contain many significant human pathogens. The acid-fast staining procedure identifies the Actinobacterial genera Mycobacterium and Nocardia.

text: Biochemical tests[edit]

text: Biochemical tests used in the identification of infectious agents include the detection of metabolic or enzymatic products characteristic of a particular infectious agent. Since bacteria ferment carbohydrates in patterns characteristic of their genus and species, the detection of fermentation products is commonly used in bacterial identification. Acids, alcohols and gases are usually detected in these tests when bacteria are grown in selective liquid or solid media.

text: The isolation of enzymes from infected tissue can also provide the basis of a biochemical diagnosis of an infectious disease. For example, humans can make neither RNA replicases nor reverse transcriptase, and the presence of these enzymes are characteristic of specific types of viral infections. The ability of the viral protein hemagglutinin to bind red blood cells together into a detectable matrix may also be characterized as a biochemical test for viral infection, although strictly speaking hemagglutinin is not an enzyme and has no metabolic function.

text: Serological methods are highly sensitive, specific and often extremely rapid tests used to identify microorganisms. These tests are based upon the ability of an antibody to bind specifically to an antigen. The antigen, usually a protein or carbohydrate made by an infectious agent, is bound by the antibody. This binding then sets off a chain of events that can be visibly obvious in various ways, dependent upon the test. For example, "Strep throat" is often diagnosed within minutes, and is based on the appearance of antigens made by the causative agent, S. pyogenes, that is retrieved from a patients throat with a cotton swab. Serological tests, if available, are usually the preferred route of identification, however the tests are costly to develop and the reagents used in the test often require refrigeration. Some serological methods are extremely costly, although when commonly used, such as with the "strep test", they can be inexpensive.[9]

text: Complex serological techniques have been developed into what are known as Immunoassays. Immunoassays can use the basic antibody – antigen binding as the basis to produce an electro-magnetic or particle radiation signal, which can be detected by some form of instrumentation. Signal of unknowns can be compared to that of standards allowing quantitation of the target antigen. To aid in the diagnosis of infectious diseases, immunoassays can detect or measure antigens from either infectious agents or proteins generated by an infected organism in response to a foreign agent. For example, immunoassay A may detect the presence of a surface protein from a virus particle. Immunoassay B on the other hand may detect or measure antibodies produced by an organism's immune system that are made to neutralize and allow the destruction of the virus.

text: Instrumentation can be used to read extremely small signals created by secondary reactions linked to the antibody – antigen binding. Instrumentation can control sampling, reagent use, reaction times, signal detection, calculation of results, and data management to yield a cost effective automated process for diagnosis of infectious disease.

text: PCR-based diagnostics[edit]

text: Technologies based upon the polymerase chain reaction (PCR) method will become nearly ubiquitous gold standards of diagnostics of the near future, for several reasons. First, the catalog of infectious agents has grown to the point that virtually all of the significant infectious agents of the human population have been identified. Second, an infectious agent must grow within the human body to cause disease; essentially it must amplify its own nucleic acids in order to cause a disease. This amplification of nucleic acid in infected tissue offers an opportunity to detect the infectious agent by using PCR. Third, the essential tools for directing PCR, primers, are derived from the genomes of infectious agents, and with time those genomes will be known, if they are not already.

text: Thus, the technological ability to detect any infectious agent rapidly and specifically are currently available. The only remaining blockades to the use of PCR as a standard tool of diagnosis are in its cost and application, neither of which is insurmountable. The diagnosis of a few diseases will not benefit from the development of PCR methods, such as some of the clostridial diseases (tetanus and botulism). These diseases are fundamentally biological poisonings by relatively small numbers of infectious bacteria that produce extremely potent neurotoxins. A significant proliferation of the infectious agent does not occur, this limits the ability of PCR to detect the presence of any bacteria.

text: Metagenomic sequencing[edit]

text: Given the wide range of bacteria, viruses, and other pathogens that cause debilitating and life-threatening illness, the ability to quickly identify the cause of infection is important yet often challenging. For example, more than half of cases of encephalitis, a severe illness affecting the brain, remain undiagnosed, despite extensive testing using state-of-the-art clinical laboratory methods. Metagenomics is currently being researched for clinical use, and shows promise as a sensitive and rapid way to diagnose infection using a single all-encompassing test. This test is similar to current PCR tests; however, amplification of genetic material is unbiased rather than using primers for a specific infectious agent. This amplification step is followed by next-generation sequencing and alignment comparisons using large databases of thousands of organismic and viral genomes.

text: Metagenomic sequencing could prove especially useful for diagnosis when the patient is immunocompromised. An ever-wider array of infectious agents can cause serious harm to individuals with immunosuppression, so clinical screening must often be broader. Additionally, the expression of symptoms is often atypical, making clinical diagnosis based on presentation more difficult. Thirdly, diagnostic methods that rely on the detection of antibodies are more likely to fail. A broad, sensitive test for pathogens that detects the presence of infectious material rather than antibodies is therefore highly desirable.

text: Indication of tests[edit]

text: There is usually an indication for a specific identification of an infectious agent only when such identification can aid in the treatment or prevention of the disease, or to advance knowledge of the course of an illness prior to the development of effective therapeutic or preventative measures. For example, in the early 1980s, prior to the appearance of AZT for the treatment of AIDS, the course of the disease was closely followed by monitoring the composition of patient blood samples, even though the outcome would not offer the patient any further treatment options. In part, these studies on the appearance of HIV in specific communities permitted the advancement of hypotheses as to the route of transmission of the virus. By understanding how the disease was transmitted, resources could be targeted to the communities at greatest risk in campaigns aimed at reducing the number of new infections. The specific serological diagnostic identification, and later genotypic or molecular identification, of HIV also enabled the development of hypotheses as to the temporal and geographical origins of the virus, as well as a myriad of other hypothesis.[9] The development of molecular diagnostic tools have enabled physicians and researchers to monitor the efficacy of treatment with anti-retroviral drugs. Molecular diagnostics are now commonly used to identify HIV in healthy people long before the onset of illness and have been used to demonstrate the existence of people who are genetically resistant to HIV infection. Thus, while there still is no cure for AIDS, there is great therapeutic and predictive benefit to identifying the virus and monitoring the virus levels within the blood of infected individuals, both for the patient and for the community at large.

text: Prevention[edit]

text: Techniques like hand washing, wearing gowns, and wearing face masks can help prevent infections from being passed from one person to another. Aseptic technique was introduced in medicine and surgery in the late 19th century and greatly reduced the incidence of infections caused by surgery. Frequent hand washing remains the most important defense against the spread of unwanted organisms.[28] There are other forms of prevention such as avoiding the use of illicit drugs, using a condom, and having a healthy lifestyle with a balanced diet and regular exercise. Cooking foods well and avoiding foods that have been left outside for a long time is also important.

text: Antimicrobial substances used to prevent transmission of infections include:

text:
antiseptics, which are applied to living tissue/skin
disinfectants, which destroy microorganisms found on non-living objects.
antibiotics, called prophylactic when given as prevention rather as treatment of infection. However, long term use of antibiotics leads to resistance of bacteria. While humans do not become immune to antibiotics, the bacteria does. Thus, avoiding using antibiotics longer than necessary helps preventing bacteria from forming mutations that aide in antibiotic resistance.

text: One of the ways to prevent or slow down the transmission of infectious diseases is to recognize the different characteristics of various diseases.[29] Some critical disease characteristics that should be evaluated include virulence, distance traveled by victims, and level of contagiousness. The human strains of Ebola virus, for example, incapacitate their victims extremely quickly and kill them soon after. As a result, the victims of this disease do not have the opportunity to travel very far from the initial infection zone.[30] Also, this virus must spread through skin lesions or permeable membranes such as the eye. Thus, the initial stage of Ebola is not very contagious since its victims experience only internal hemorrhaging. As a result of the above features, the spread of Ebola is very rapid and usually stays within a relatively confined geographical area. In contrast, the Human Immunodeficiency Virus (HIV) kills its victims very slowly by attacking their immune system.[9] As a result, many of its victims transmit the virus to other individuals before even realizing that they are carrying the disease. Also, the relatively low virulence allows its victims to travel long distances, increasing the likelihood of an epidemic.

text: Another effective way to decrease the transmission rate of infectious diseases is to recognize the effects of small-world networks.[29] In epidemics, there are often extensive interactions within hubs or groups of infected individuals and other interactions within discrete hubs of susceptible individuals. Despite the low interaction between discrete hubs, the disease can jump to and spread in a susceptible hub via a single or few interactions with an infected hub. Thus, infection rates in small-world networks can be reduced somewhat if interactions between individuals within infected hubs are eliminated (Figure 1). However, infection rates can be drastically reduced if the main focus is on the prevention of transmission jumps between hubs. The use of needle exchange programs in areas with a high density of drug users with HIV is an example of the successful implementation of this treatment method. [6] Another example is the use of ring culling or vaccination of potentially susceptible livestock in adjacent farms to prevent the spread of the foot-and-mouth virus in 2001.[31]

text: A general method to prevent transmission of vector-borne pathogens is pest control.

text: Immunity[edit]

text: Infection with most pathogens does not result in death of the host and the offending organism is ultimately cleared after the symptoms of the disease have waned.[8] This process requires immune mechanisms to kill or inactivate the inoculum of the pathogen. Specific acquired immunity against infectious diseases may be mediated by antibodies and/or T lymphocytes. Immunity mediated by these two factors may be manifested by:

text:
a direct effect upon a pathogen, such as antibody-initiated complement-dependent bacteriolysis, opsonoization, phagocytosis and killing, as occurs for some bacteria,
neutralization of viruses so that these organisms cannot enter cells,
or by T lymphocytes, which will kill a cell parasitized by a microorganism.

text: The immune system response to a microorganism often causes symptoms such as a high fever and inflammation, and has the potential to be more devastating than direct damage caused by a microbe.[9]

text: Resistance to infection (immunity) may be acquired following a disease, by asymptomatic carriage of the pathogen, by harboring an organism with a similar structure (crossreacting), or by vaccination. Knowledge of the protective antigens and specific acquired host immune factors is more complete for primary pathogens than for opportunistic pathogens. There is also the phenomenon of herd immunity which offers a measure of protection to those otherwise vulnerable people when a large enough proportion of the population has acquired immunity from certain infections.

text: Immune resistance to an infectious disease requires a critical level of either antigen-specific antibodies and/or T cells when the host encounters the pathogen. Some individuals develop natural serum antibodies to the surface polysaccharides of some agents although they have had little or no contact with the agent, these natural antibodies confer specific protection to adults and are passively transmitted to newborns.

text: Host genetic factors[edit]

text: The organism that is the target of an infecting action of a specific infectious agent is called the host. The host harbors and agent in a mature, or sexually active stage phase called the definitive host. The intermediate host comes in contact during the larvae stage. A host can be anything living and can attain to asexual and sexual reproduction.[32] The clearance of the pathogens, either treatment-induced or spontaneous, it can be influenced by the genetic variants carried by the individual patients. For instance, for genotype 1 hepatitis C treated with Pegylated interferon-alpha-2a or Pegylated interferon-alpha-2b (brand names Pegasys or PEG-Intron) combined with ribavirin, it has been shown that genetic polymorphisms near the human IL28B gene, encoding interferon lambda 3, are associated with significant differences in the treatment-induced clearance of the virus. This finding, originally reported in Nature,[33] showed that genotype 1 hepatitis C patients carrying certain genetic variant alleles near the IL28B gene are more possibly to achieve sustained virological response after the treatment than others. Later report from Nature[34] demonstrated that the same genetic variants are also associated with the natural clearance of the genotype 1 hepatitis C virus.

text: Treatments[edit]

text: When infection attacks the body, anti-infective drugs can suppress the infection. Several broad types of anti-infective drugs exist, depending on the type of organism targeted; they include antibacterial (antibiotic; including antitubercular), antiviral, antifungal and antiparasitic (including antiprotozoal and antihelminthic) agents. Depending on the severity and the type of infection, the antibiotic may be given by mouth or by injection, or may be applied topically. Severe infections of the brain are usually treated with intravenous antibiotics. Sometimes, multiple antibiotics are used in case there is resistance to one antibiotic. Antibiotics only work for bacteria and do not affect viruses. Antibiotics work by slowing down the multiplication of bacteria or killing the bacteria. The most common classes of antibiotics used in medicine include penicillin, cephalosporins, aminoglycosides, macrolides, quinolones and tetracyclines.[citation needed]

text: Not all infections require treatment, and for many self-limiting infections the treatment may cause more side-effects than benefits. Antimicrobial stewardship is the concept that healthcare providers should treat an infection with an antimicrobial that specifically works well for the target pathogen for the shortest amount of time and to only treat when there is a known or highly suspected pathogen that will respond to the medication.[35]

text: Epidemiology[edit]

text: In 2010 about 10 million people died of an infectious disease.[37]

text: The World Health Organization collects information on global deaths by International Classification of Disease (ICD) code categories. The following table lists the top infectious disease by number of deaths in 2002. 1993 data is included for comparison.

text:
Worldwide mortality due to infectious diseases[38][39]

Rank
Cause of death
Deaths 2002
(in millions)
Percentage of
all deaths
Deaths 1993
(in millions)
1993 Rank

N/A
All infectious diseases
14.7
25.9%
16.4
32.2%

1
Lower respiratory infections[40]
3.9
6.9%
4.1
1

2
HIV/AIDS
2.8
4.9%
0.7
7

3
Diarrheal diseases[41]
1.8
3.2%
3.0
2

4
Tuberculosis (TB)
1.6
2.7%
2.7
3

5
Malaria
1.3
2.2%
2.0
4

6
Measles
0.6
1.1%
1.1
5

7
Pertussis
0.29
0.5%
0.36
7

8
Tetanus
0.21
0.4%
0.15
12

9
Meningitis
0.17
0.3%
0.25
8

10
Syphilis
0.16
0.3%
0.19
11

11
Hepatitis B
0.10
0.2%
0.93
6

12-17
Tropical diseases (6)[42]
0.13
0.2%
0.53
9, 10, 16–18

Note: Other causes of death include maternal and perinatal conditions (5.2%), nutritional deficiencies (0.9%),
noncommunicable conditions (58.8%), and injuries (9.1%).

text: The top three single agent/disease killers are HIV/AIDS, TB and malaria. While the number of deaths due to nearly every disease have decreased, deaths due to HIV/AIDS have increased fourfold. Childhood diseases include pertussis, poliomyelitis, diphtheria, measles and tetanus. Children also make up a large percentage of lower respiratory and diarrheal deaths. In 2012, approximately 3.1 million people have died due to lower respiratory infections, making it the number 4 leading cause of death in the world.[43]

text: Historic pandemics[edit]

text: A pandemic (or global epidemic) is a disease that affects people over an extensive geographical area.

text:
Plague of Justinian, from 541 to 542, killed between 50% and 60% of Europe's population.[44]
The Black Death of 1347 to 1352 killed 25 million in Europe over 5 years. The plague reduced the old world population from an estimated 450 million to between 350 and 375 million in the 14th century.
The introduction of smallpox, measles, and typhus to the areas of Central and South America by European explorers during the 15th and 16th centuries caused pandemics among the native inhabitants. Between 1518 and 1568 disease pandemics are said to have caused the population of Mexico to fall from 20 million to 3 million.[45]
The first European influenza epidemic occurred between 1556 and 1560, with an estimated mortality rate of 20%.[45]
Smallpox killed an estimated 60 million Europeans during the 18th century[46] (approximately 400,000 per year).[47] Up to 30% of those infected, including 80% of the children under 5 years of age, died from the disease, and one-third of the survivors went blind.[48]
In the 19th century, tuberculosis killed an estimated one-quarter of the adult population of Europe;[49] by 1918 one in six deaths in France were still caused by TB.
The Influenza Pandemic of 1918 (or the Spanish Flu) killed 25–50 million people (about 2% of world population of 1.7 billion).[50] Today Influenza kills about 250,000 to 500,000 worldwide each year.

text: Emerging diseases[edit]

text: In most cases, microorganisms live in harmony with their hosts via mutual or commensal interactions. Diseases can emerge when existing parasites become pathogenic or when new pathogenic parasites enter a new host.

text:
Coevolution between parasite and host can lead to hosts becoming resistant to the parasites or the parasites may evolve greater virulence, leading to immunopathological disease.
Human activity is involved with many emerging infectious diseases, such as environmental change enabling a parasite to occupy new niches. When that happens, a pathogen that had been confined to a remote habitat has a wider distribution and possibly a new host organism. Parasites jumping from nonhuman to human hosts are known as zoonoses. Under disease invasion, when a parasite invades a new host species, it may become pathogenic in the new host.[51]

tag: ol

text: Several human activities have led to the emergence of zoonotic human pathogens, including viruses, bacteria, protozoa, and rickettsia,[52] and spread of vector-borne diseases,[51] see also globalization and disease and wildlife disease:

text:
Encroachment on wildlife habitats. The construction of new villages and housing developments in rural areas force animals to live in dense populations, creating opportunities for microbes to mutate and emerge.[53]
Changes in agriculture. The introduction of new crops attracts new crop pests and the microbes they carry to farming communities, exposing people to unfamiliar diseases.
The destruction of rain forests. As countries make use of their rain forests, by building roads through forests and clearing areas for settlement or commercial ventures, people encounter insects and other animals harboring previously unknown microorganisms.
Uncontrolled urbanization. The rapid growth of cities in many developing countries tends to concentrate large numbers of people into crowded areas with poor sanitation. These conditions foster transmission of contagious diseases.
Modern transport. Ships and other cargo carriers often harbor unintended "passengers", that can spread diseases to faraway destinations. While with international jet-airplane travel, people infected with a disease can carry it to distant lands, or home to their families, before their first symptoms appear.

text: History[edit]

text: Ideas of contagion became more popular in Europe during the Renaissance, particularly through the writing of the Italian physician Girolamo Fracastoro.[54]

text: Anton van Leeuwenhoek (1632–1723) advanced the science of microscopy by being the first to observe microorganisms, allowing for easy visualization of bacteria.

text: In the mid-19th century John Snow and William Budd did important work demonstrating the contagiousness of typhoid and cholera through contaminated water. Both are credited with decreasing epidemics of cholera in their towns by implementing measures to prevent contamination of water.[55]

text: Louis Pasteur proved beyond doubt that certain diseases are caused by infectious agents, and developed a vaccine for rabies.

text: Robert Koch, provided the study of infectious diseases with a scientific basis known as Koch's postulates.

text: Edward Jenner, Jonas Salk and Albert Sabin developed effective vaccines for smallpox and polio, which would later result in the eradication and near-eradication of these diseases, respectively.

text: Alexander Fleming discovered the world's first antibiotic, Penicillin, which Florey and Chain then developed.

text: Gerhard Domagk developed sulphonamides, the first broad spectrum synthetic antibacterial drugs.

text: Medical specialists[edit]

text: The medical treatment of infectious diseases falls into the medical field of Infectious Disease and in some cases the study of propagation pertains to the field of Epidemiology. Generally, infections are initially diagnosed by primary care physicians or internal medicine specialists. For example, an "uncomplicated" pneumonia will generally be treated by the internist or the pulmonologist (lung physician). The work of the infectious diseases specialist therefore entails working with both patients and general practitioners, as well as laboratory scientists, immunologists, bacteriologists and other specialists.

text: An infectious disease team may be alerted when:

text:
The disease has not been definitively diagnosed after an initial workup
The patient is immunocompromised (for example, in AIDS or after chemotherapy);
The infectious agent is of an uncommon nature (e.g. tropical diseases);
The disease has not responded to first line antibiotics;
The disease might be dangerous to other patients, and the patient might have to be isolated

text: Society and culture[edit]

text: A number of studies have reported associations between pathogen load in an area and human behavior. Higher pathogen load is associated with decreased size of ethnic and religious groups in an area. This may be due high pathogen load favoring avoidance of other groups, which may reduce pathogen transmission, or a high pathogen load preventing the creation of large settlements and armies that enforce a common culture. Higher pathogen load is also associated with more restricted sexual behavior, which may reduce pathogen transmission. It also associated with higher preferences for health and attractiveness in mates. Higher fertility rates and shorter or less parental care per child is another association that may be a compensation for the higher mortality rate. There is also an association with polygyny which may be due to higher pathogen load, making selecting males with a high genetic resistance increasingly important. Higher pathogen load is also associated with more collectivism and less individualism, which may limit contacts with outside groups and infections. There are alternative explanations for at least some of the associations although some of these explanations may in turn ultimately be due to pathogen load. Thus, polygny may also be due to a lower male:female ratio in these areas but this may ultimately be due to male infants having increased mortality from infectious diseases. Another example is that poor socioeconomic factors may ultimately in part be due to high pathogen load preventing economic development.[56]

text: Fossil record[edit]

text: Evidence of infection in fossil remains is a subject of interest for paleopathologists, scientists who study occurrences of injuries and illness in extinct life forms. Signs of infection have been discovered in the bones of carnivorous dinosaurs. When present, however, these infections seem to tend to be confined to only small regions of the body. A skull attributed to the early carnivorous dinosaur Herrerasaurus ischigualastensis exhibits pit-like wounds surrounded by swollen and porous bone. The unusual texture of the bone around the wounds suggests they were afflicted by a short-lived, non-lethal infection. Scientists who studied the skull speculated that the bite marks were received in a fight with another Herrerasaurus. Other carnivorous dinosaurs with documented evidence of infection include Acrocanthosaurus, Allosaurus, Tyrannosaurus and a tyrannosaur from the Kirtland Formation. The infections from both tyrannosaurs were received by being bitten during a fight, like the Herrerasaurus specimen.[57]

text: Outer space[edit]

text: A 2006 Space Shuttle experiment found that Salmonella typhimurium, a bacterium that can cause food poisoning, became more virulent when cultivated in space.[58] On April 29, 2013, scientists in Rensselaer Polytechnic Institute, funded by NASA, reported that, during spaceflight on the International Space Station, microbes seem to adapt to the space environment in ways "not observed on Earth" and in ways that "can lead to increases in growth and virulence".[59] More recently, in 2017, bacteria were found to be more resistant to antibiotics and to thrive in the near-weightlessness of space.[60] Microorganisms have been observed to survive the vacuum of outer space.[61][62]