Introduction
Foot and mouth disease (FMD)also called Aphthous fever is a highly contagious disease that affects cloven-footed animals( cattle, buffalo, goat, sheep, pig, camel, and cloven-footed wildlife species) and is named vesicular lesions mostly found in and around the mouth and on foot and in lactating females mostly of cattle lesions may found on teats.
Etiology of FMD
Foot and mouth disease virus (FMDV) is a nonenveloped RNA virus of the viral family Picornaviridae and genus Aphthovirus that causes FMD.
Serotypes of FMDV
Foot and mouth disease virus (FMDV) has 7 major serotypes (A, O, C, Asia 1, SAT 1, SAT 2, SAT 3).
Epidemiology of FMD
Foot and mouth disease affects all cloven-footed animals and there are three major outbreaks of foot and mouth disease (FMD). The first outbreaks of FMD occurred in Great Britain in 2001,
another outbreak occurred in the Republic of Korea in 2010/2011 and a third major outbreak of foot and mouth disease (FMD) occurred in Japan in 2010. FMD outbreaks in North America, the last outbreak in the United States occurred in 1929, Canada in 1951-1952, in Mexico in 1946-1954.
- Serotypes of foot and mouth disease(FMDV) in Africa are 6 out of a total of 7 are
SAT 1, SAT 2, SAT 3, A, O and C. - Serotypes of foot and mouth disease(FMDV) in Asia are 4
A, O, C, Asia 1. - Serotypes of foot and mouth disease(FMDV) in South America are 3
A, O, C.
Prevalence of Foot and mouth disease
There is no specific data about FMD prevalence in different countries.
Usually, serotypes A and O are responsible for most outbreaks. Outbreaks with serotype C are uncommon.
Morbidity and Case Fatality in FMD
Morbidity in FMD in outbreaks in susceptible animals may reach 100%
But case fatality is very low in older animals, about 2%, and a bit high in young animals, about 20%.In 1997, an outbreak in Taiwan Case fatality in pigs was 18% but reached 100%.
Transmission of FMD
Transmission of FMD occurs from one animal to another by aerosols and ingestion. In transmission direct contact is very important in FMD spread.
Spread of FMD from pigs to cattle by the movement of people, slaughterhouse waste, or animals. Cattle are more susceptible to airborne transmission. FMDV can spread about 250km by using water as a medium and 100km by land.
Serotype A takes a lower time of exposure for contact transmission than serotypes O and C.
FMDV is shed in saliva, semen, and milk after viremia before showing clinical signs of pressure of mouth, teeth, and foot lesions.
Animals during convalescence or that receive vaccines are carriers. Virus of FMDV pass UN changed through the git of birds and can source of long-distance virus transmission by acting as carriers.
Risk factors for FMD
Host-specific
Cattle and pigs are more suspectable to FMD. Goats are infrequent carriers of FMDV, but sheep are not at all.
Equines are not suspectable for FMD.
In camelid, dromedaries are not suspectable for FMD but Bactrian are suspectable for FMD.
African buffalo are a source of the SAT virus.
Asian buffalo are also suspectable for FMD and spread from one another.
Environmental factors
FMD virus can persist for 1 year in infected premises and 10- 12 weeks on clothes and feed and also in semen for more than 60 days frozen to -97C°(110 F°).
Viruses can be destroyed by direct sunlight, but low temperature enables its presence on feed and other materials.
The virus can be destroyed in minutes using disinfectants such as sodium hydroxide or formalin and sodium carbonate.
Pathogenesis of FMD
Usually involves three phases
1) Previremic phase
It involves infection and replication at replication sites and lasts for 3 weeks.
The primary site of replication in Cattle is a nasopharyngeal region.
FMDV affects innate immunity by blocking interferon response and also influences natural killer cells to recognize and eliminate FMDV.
2) Viremic form
It is characterized by the presence of the virus in blood and disseminated to epidermal sites of the mouth feet, teats, and snouts of pigs and lasts for 1 to 21 days.
Viruses are shed in this phase in urine, milk, semen, saliva, inhaled air, and feces for 2 weeks.
3) Postviremic
It is characterized by the healing of lesions
of FMD in the mouth, feet, snouts of pigs, and teats of lactating cows.
Oral lesions heal more rapidly than feet and teats.
Clinical findings
Animals affected with Footal and mouth disease show the following clinal findings:
.Fever 104 – 106, C°
.Fall in milk yield
. Anorexia
.Painful stomatitis
. Salvation (Sting-like rope )
. Vesicles on the buccal mucosa, dental pad tongue, feet, corone, snouts, and teats.
. Lameness
. Recumbent
. Mastitis
.Off feed
. Necrotic myocarditis in young animals
. Dysentery
. Diarrhea
. Enteritis
Sequelae of FMD
. Decrease milk production
. Hypertrichosis (hairy panter)
. Pituitary damage-related dyspnea syndrome
.heat intolerance
The sequelae of hairy panter is mostly present in European cattle breeds.
Differential diagnosis by
- Vesicular Stomatitis:
- Vesicular Exanthema:
- Swine Vesicular Disease
- Bovine Viral Diarrhoea (BVD
- Rinderpest
- Malignant Catarrhal Fever (MCF)
Treatment of FMD
No anti-viral treatments in food animals but supportive and symptomatic
.Penicillin
. Protective dressing to prevent secondary infection
.NSAIDS (Flunixin meglumine)
. Ethnoveterinary remedies like soda ash washing, applying honey and finger millet flour for 3 days.
. Porcine type 1 interferon
. Bovine type 3 interferon
Control:
.Vaccination in endemic areas with killed vaccine R-1.
. By maintaining biosecurity
. Restricted movement and trade of infected animals
Vaccination of FMD
Use killed trivalent vaccine (A, O, C) in infected animals. Vaccination single dose provides immunity for 6 or 7 months.
Cattle must be vaccinated after every 6 months. Calves from unvaccinated dams vaccinate at age 4 months and revaccinate at 8 months. Calves from vaccinated dams vaccinate at age 6 months and revaccinate at 10 months of age. Goats and sheep aren’t included in the vaccination program unless outbreaks occur.
Zoonotic status of FMD
Humans are considered to be susceptible to viruses and may contain lesions on the hands and mouth, but cases are few except those that work with the carcasses of animals and laboratory personnel. Moreover, humans and their clothes are a source of virus transmission.
FAQ’S
- What is FMD?
A highly contagious viral disease affecting cloven-hoofed animals, causing systemic illness with lesions in the mouth and feet, leading to significant economic and trade impacts. - Why is FMD important?
It disrupts livestock productivity, triggers trade embargoes, and requires costly control measures, making it a global concern for agriculture and food security. - How does FMD spread?
Through direct contact, aerosols, contaminated objects, and movement of infected animals or products, highlighting the need for strict biosecurity. - What are the key symptoms?
Fever, vesicles (blisters) in the mouth and on the feet, drooling, lameness, and a drop in milk production, often resembling other vesicular diseases. - Can humans get FMD?
No, but humans can act as carriers, spreading the virus to animals through contaminated clothing, equipment, or vehicles.
