{{Infobox_Disease |
  Name           = 口蹄疫 |
  Image          = |
  Caption        = |
  DiseasesDB     = 31707 |
  ICD10          =  |
  ICD9           =  |
  ICDO           = |
  OMIM           = |
  MedlinePlus    = |
  eMedicineSubj  = |
  eMedicineTopic = |
  MeshID         = D005536 |
}}
{{Taxobox 
| color = violet 
| name = 口蹄疫病毒
| image = Foot-and-Mouth-Disease-Virus.png
| image_caption = 口蹄疫病毒的外壳蛋白
| virus_group = iv
| familia = 微小核糖核酸病毒科(Picornaviridae)
| genus = 鵝口瘡病毒屬(Aphthovirus)
| species = '''''口蹄疫病毒'''''
}}
'''口蹄疫'''（学名：'''Aphtae epizooticae'''，'''foot-and-mouth disease'''或'''hoof-and-mouth disease'''，簡稱'''FMD'''）是牛和猪的一种非致命的病毒传染病。由于历史原因，在中国大陆该病也称为“五号病”或“W病”。它也可以感染鹿、山羊、绵羊和其它偶蹄动物，比如象、鼠和刺猬。马和人類感染病例則非常少。1897年，Friedrich Loeffler首先揭示口蹄疫起因为病毒。他将感染动物的血液穿过良好的瓷玻璃过滤器，发现收集到的液体还能够在健康动物中致病。

口蹄疫在全球许多地区（包括英国爆发的口蹄疫导致了该国境内大量的牲畜被屠宰。在此期间，诸如Ten Tors等一系列的体育赛事和休闲运动也纷纷被取消。萨里郡农场再次出现口蹄疫疫情。 

==病原学==
口蹄疫是由小核糖核酸病毒科的一种口蹄疫病毒属的病毒引起的。口蹄疫病毒有7种抗原性截然不同的血清型。

== 症状 ==
对于畜类，口蹄疫的症状主要是二至三天后快速下降的载体，它们同样会传染该疾病。

口蹄疫的感染发生一般是地域性的，这就是说，病毒通过直接接触受感染的动物传播给易感染动物，或者通过被污染的钢笔或运输牲畜的货车。动物管理人（如农场工人）的外衣或皮肤，动物接触过的水，和未煮过的食物碎屑以及包含感染动物产品的饲料添加剂都可能是病毒的携带源。特别的，母牛可以通过公牛精液传染上口蹄疫。对其的控制可以是隔离或销毁受感染的牲畜, 以及禁止向未有感染疫情的国家出口动物肉类以及相关动物产品。

人类可能通过接触受感染动物而罹患口蹄疫，但这种情况很罕见。因为口蹄疫病毒对胃酸敏感，所以人类通常不会通过食用肉类感染口蹄疫病毒。在英国，最後一次确认人类罹患口蹄疫是在1967年。在欧洲大陆，非洲以及南美也只有很少感染案例。口蹄疫感染人类的症状包括不舒服，发烧，呕吐，口腔组织发生红色溃疡腐烂（表面腐蚀性水疱），偶有皮肤小水疱。对于人类，值得注意的是，该症状与另外一种病毒疾病的症状类似，那种疾病通常称为“手足口病”，更频繁地发生在人类身上，特别是小儿；那种疾病是由小核糖核酸病毒科的另一种病毒引起，它是一种称为柯萨奇A病毒的肠道病毒。因为口蹄疫很少传染人类但在动物间会以非常快的速度传染，所以它对农畜业的危害比对人类健康的危害要大的多。 位于世界各地的农民当口蹄疫疫情流行时可能一年的损失高达10亿美圆，其更将导致大量畜类被销毁以及来自牛奶与肉类产品收入的巨幅减少。

{{Infobox_Disease |
  Name           = Foot-and-mouth disease |
  Image          = |
  Caption        = |
  DiseasesDB     = 31707 |
  ICD10          =  |
  ICD9           =  |
  ICDO           = |
  OMIM           = |
  MedlinePlus    = |
  eMedicineSubj  = |
  eMedicineTopic = |
  MeshID         = D005536 |
}}
{{Taxobox 
| color = violet 
| name = ''Foot-and-mouth disease virus''
| image = Foot-and-Mouth-Disease-Virus.png
| image_caption = Foot-and-mouth disease virus-coating protein
| virus_group = iv
| familia = ''Picornaviridae''
| genus = ''Aphthovirus''
| type_species = '''''Foot-and-mouth disease virus'''''
}}
'''Foot-and-mouth disease''' (FMD, binomial ''Aphtae epizooticae''), sometimes called '''hoof-and-mouth disease''', is a highly contagious and sometimes fatal viral water buffalo, sheep, and other cloven hooves. 

In addition, hedgehogs <ref name=hedgehog>J. D. McLauchlan, W. M. Henderson 'The Occurrence of Foot-and-Mouth Disease in the Hedgehog under Natural Conditions', The Journal of Hygiene, Vol. 45, No. 4 (Dec., 1947), pp. 474-479</ref> and elephants<ref name=animals>[http://www.inspection.gc.ca/english/anima/heasan/disemala/fmdfie/plan/plan-1e.shtml Canadian Food Inspection Agency - Animal Products - Foot-and-Mouth Disease Hazard Specific Plan<!-- Bot generated title -->]</ref> are susceptible to the disease.The Llama and Alpaca may develop mild symptoms but are resistant to the disease and will not pass it on to others of the same species.<ref name=animals/> In laboratory experiments, mice, rats and chicken have been successfully infected by artificial means, but it is not believed that they would contract the disease under natural conditions. <ref name=animals/>
Just as humans may spread the disease by carrying the germs on their clothes and body, animals that are not susceptible to the disease may still aid in spreading it. This was the case in Canada in 1952 when an outbreak flared up again after dogs had carried off bones from dead animals.<ref name=animals/> Wolves are thought to play a similar role in the former Soviet Union.<ref name="Graves"></ref> 

Humans are very rarely affected. Foot-and-mouth disease virus (FMDV) is the prototypic member of the Aphthovirus genus in the Picornaviridae family. This picornavirus is the etiological agent of the acute systemic vesicular disease that affects cattle and other animals worldwide. It is a highly variable and transmissible virus.<ref></ref>

The cause of FMD was first shown to be viral in 1897 by Friedrich Loeffler.  He passed the blood of an infected animal through a fine porcelain filter and found that the fluid that was collected could still cause the disease in healthy animals.  

FMD occurs throughout much of the world, and whilst some countries have been free of FMD for some time, its wide host range and rapid spread represent cause for international concern. After World War II, the disease was widely distributed throughout the world. In 1996, endemic areas included Asia, Africa, and parts of South America; as of August 2007, Chile is disease free,<ref>{{cite paper
  | title = Foot and Mouth Disease
  | publisher = Washington State Department of Health
  | date = March 2002
  | url = http://www.doh.wa.gov/ehp/ts/zoo/foot-and-mouth-disease.pdf
  | format = PDF
  | accessdate = 2007-08-05
}}</ref> and Uruguay and Argentina have not had an outbreak since 2001. North America, Australia and Japan have been free of FMD for many years. New Zealand has never had a case of foot and mouth disease.<ref>http://www.biosecurity.govt.nz/pests-diseases/animals/foot-n-mouth/freedom-statement.htm, official government press release, New Zealand's Freedom From Foot And Mouth Disease, Biosecurity New Zealand, accessdate = 2007-08-06 </ref> Most European countries have been recognized as disease free, and countries belonging to the European Union have stopped FMD vaccination.

However, in 2001, a serious outbreak of FMD in Britain resulted in the slaughter of many animals, the postponing of the general election for a month, and the cancellation of many sporting events and leisure activities such as the Isle of Man TT. Due to strict government policies on sale of livestock, disinfection of all persons leaving and entering farms and the cancellation of large events likely to be attended by farmers, a potentially economically disastrous epizootic was avoided in the Republic of Ireland, with just one case recorded in Proleek, Co. Louth. In August 2007, FMD was found at two farms in Surrey, England. All livestock were culled and a quarantine erected over the area. There have since been two other suspected outbreaks, although these seem now not to be related to FMD.

There are seven FMD serotypes: O, A, C, SAT-1, SAT-2, SAT-3, and Asia-1. These serotypes show some regionality, and the O serotype is most common.

==Symptoms==
The average incubation period of the Foot and Mouth virus varies but is generally around 3-8 days.<ref></ref> The disease is characterised by high carry FMD and can transmit it to others.

thumb|left|Ruptured oral vesicle in a cow with FMD
Infection with foot-and-mouth disease tends to occur locally - that is, the virus is passed on to susceptible animals through direct contact with infected animals or with contaminated pens or vehicles used to transport livestock.  The clothes and skin of animal handlers such as farmers, standing water, and uncooked food scraps and feed supplements containing infected animal products can harbor the virus as well.  Cows can also catch FMD from the semen of infected bulls.  Control measures include quarantine and destruction of infected livestock, and export bans for meat and other animal products to countries not infected with the disease.

thumb|Ruptured blisters on the feet of a pig with FMD
Foot-and-mouth disease is caused by FMDV, an ''lyses (bursts) and releases the new viruses.

==Foot-and-mouth disease infecting humans==
Humans can be infected with foot-and-mouth disease through contact with infected animals, but this is extremely rare. Some cases were caused by laboratory accidents. Because the virus that causes FMD is sensitive to stomach acid, it cannot spread to humans via consumption of infected meat, except in the mouth before the meat is swallowed. In the UK, the last confirmed human case occurred in 1966<ref></ref><ref></ref>, and only a few other cases have been recorded in countries of continental Europe, Africa, and South America. Symptoms of FMD in humans include malaise, fever, vomiting, red ulcerative lesions (surface-eroding damaged spots) of the oral tissues, and sometimes vesicular lesions (small blisters) of the skin. According to a newspaper report Foot and Mouth disease killed two children in England in 1884, suspectedly due to infected milk.<ref></ref>

There is another viral disease with similar symptoms, commonly referred to as "hand, foot and mouth disease", that occurs more frequently in humans, especially in young children; the cause, Coxsackie A virus, is different from FMDV. Both are members of the ''Picornaviridae'' family, but while FMDV belongs to the ''Aphthovirus'' genus, Coxsackie viruses belong to the ''Enteroviruses''.

Because FMD rarely infects humans but spreads rapidly among animals, it is a much greater threat to the agriculture industry than to human health.  Farmers around the world can lose huge amounts of money during a foot-and-mouth epizootic, when large numbers of animals are destroyed and revenues from milk and meat production go down.

'''External links:'''
* [http://www.bmj.com/cgi/content/full/322/7286/565] Description
* A case in 1966: <ref>Armstrong R, Davie J, Hedger RS. ''Foot-and-mouth disease in man.'' BMJ 1967; 4: 529-530.</ref>
* [http://www.guardian.co.uk/footandmouth/story/0,,604980,00.html In the 1884 outbreak in Britain]

==Virus replication==
Soon after infection, the single stranded positive RNA that constitutes the viral genome is efficiently translated using a cap-independent mechanism driven by the internal ribosome entry site element (IRES). This process occurs concomitantly with the inhibition of cellular protein synthesis, caused by the expression of viral proteases. Processing of the viral polyprotein is achieved cotranslationally by viral encoded proteases, giving rise to the different mature viral proteins. Viral RNA as well as viral proteins interact with different components of the host cell, acting as key determinants of viral pathogenesis. In depth knowledge of the molecular basis of the viral cycle is needed to control viral pathogenesis and disease spreading.<ref></ref>

==Vaccination==
thumb|Plum Island Animal Disease Center
Seven main types of Foot and Mouth Virus are believed to exist<ref>http://copus.org.uk/page.asp?id=1253 Foot and Mouth Virus Information</ref>. Like other viruses, the FMD virus continually evolves and mutates, thus one of the difficulties in vaccinating against FMD is the huge variation between and even within serotypes.  There is no cross-protection between strains within a given serotype may have nucleotide sequences that differ by as much as 30% for a given gene.  This means that FMD immunity that lasts from months to years.  

Currently, the  World Organisation for Animal Health recognizes countries to be in one of three disease states with regards to FMD: ''FMD present with or without vaccination'', ''FMD-free with vaccination'', and ''FMD-free without vaccination''.  Countries that are designated FMD-free without vaccination have the greatest access to export markets, and therefore many developed nations, including Canada, the United States, and the UK, work hard to maintain their current ''FMD-free without vaccination'' status.

There are several reasons cited for restricting export from countries using FMD vaccines. The most important is probably that routine blood tests, relying on antibodies, cannot distinguish between an infected and a vaccinated animal.<ref>Canadian Food Inspection Agency Q&A, question 20. http://www.inspection.gc.ca/english/anima/heasan/disemala/fmdfie/questionse.shtml</ref> This would severely hamper screening of animals used in export products, risking a spread of FMD to importing countries. A widespread preventive vaccination would also conceal the existence of the virus in a country. From there, it could potentially spread to countries without vaccine programs. Lastly, an animal that is infected shortly after being vaccinated can harbour and spread FMD without showing symptoms itself, hindering containment and culling of sick animals as a remedy.

Many early genetically engineered vaccine.

The North American FMD Vaccine Bank is housed at the United States Department of Agriculture's (USDA) Foreign Animal Disease Diagnostic Laboratory (FADDL) at Plum Island Animal Disease Center. The Center, located 1.5 miles off the coast of Long Island, NY, is the only place in the United States where scientists can conduct research and diagnostic work on highly contagious animal diseases such as FMD. Because of this limitation US companies working on FMD usually use facilities in other countries where such diseases are endemic.

==Outbreaks==
===US, 1914===
The US has had 9 FMD outbreaks since 1870. The most devastating outbreak happened in 1914. It originated from Michigan but it was its entry into the stockyards in Chicago that turned it into an epizootic. 3500 livestock herds were infected across the US, totaling over 170000 cattle, sheep and swine. The eradication came at a cost of 4.5 million 1914 USD dollars. A 1924 outbreak in California resulted not only in the slaughter of 109000 farm animals, but also 22000 deer. 
The US saw its latest FMD outbreak in Montebello, California in 1929. This outbreak originated in hogs that had eaten infected meat scraps from a tourist steamship that had stocked meat in Argentina. 3600 animals were slaughtered and the disease was contained in as little as one month.<ref name=EDEN>EDEN http://www.eden.lsu.edu/Issues_View.aspx?IssueID=5f3b1efb-d295-4d8e-9cab-8e3bba3c3824</ref><ref>CRS Report for Congress - Foot and Mouth Disease:
A Threat to U.S. Agriculture, Segarra, Rawson. http://www.nationalaglawcenter.org/assets/crs/RS20890.pdf</ref>

===United Kingdom, 1967===

In October 1967, a farmer in Shropshire reported a lame sow which was later diagnosed with FMD. The source was believed to be remains of legally-imported infected lamb from Argentina and Chile. The virus spread and in total, 442,000 animals were slaughtered and the outbreak had an estimated cost of £370 million.

===Taiwan, 1997===
Taiwan had previous outbreaks of FMD in 1913-14 and 1924-29 but had since been spared epidemics <ref>Foot-and-mouth virus: A global dilemma http://archives.cnn.com/2001/WORLD/europe/02/27/farming.world/index.html</ref> and considered itself free of FMD as late as in the 1990's. On the 19th of March 1997 a swine sow at a farm in Hsinchu prefecture, Taiwan was diagnosed with a strain of FMD that only infects swine. Mortality was high, nearing 100% in the infected flock. The cause of the outbreak was not determined, but the farm was near a port city known for its pig smuggling industry and illegal slaughterhouses. Smuggled swine or contaminated meat are thus likely sources of the disease. 