Sacred Animal Project

What is Foot and Mouth Disease (FMD)?

Foot and mouth disease (FMD) is a brutal and highly contagious viral disease of livestock that has a major economic impact. The disease affects cattle, goats, sheep, swine, and other cloven-hoofed ruminants.

FMD is characterized by fever and blister-like sores on the tongue, lips, in the mouth, on the teats and between the hooves. The disease causes severe production losses, and while the mass affected animals recover, the disease often leaves them weakened and injured. The disease is seldom fatal in adult animals, but there is often high mortality in young animals due to Myocarditis or, when the dam is infected by the disease, lack of milk. However, it causes severe pain and distress, especially in cattle; leading to permanent lameness in animals and reduction in the productivity of recovered animals.

Cause

The disease is caused by a virus of Picornaviridae family consisting of seven ‘types’ (A, O, C, SAT1, SAT2, SAT3, and Asia1), each producing the similar symptoms which are distinguishable only in the laboratory and is considered endemic in different countries worldwide. Immunity to its one type does not protect an animal against its other types. Each disease requires a specific vaccine to provide immunity to the vaccinated animal.

The interval between exposure to infection and the appearance of symptoms varies between twenty-four hours and ten days, and sometimes even longer. The average time under natural conditions ranges between three to six days.

The virus survives at neutral pH in lymph nodes and bone marrow, but when the pH is less than 6.0, it gets destroyed in muscle, i.e., after rigor mortis. The virus can persist in contaminated fodder and the environment for a period of up to one month depending on the existing temperature and pH conditions.

Airborne spread of the disease takes place and under favourable weather conditions the disease may be spread at considerable distances by this route.

Animals get infected with the virus either by direct contact with a suffering animal, by contact with foodstuffs or other things contaminated by such an animal, by eating or coming into contact with some part of an infected carcass.

Outbreaks of FMD have been associated with the import of infected meat and meat products.

The disease can also be spread by people, vehicles and other objects contaminated by this virus.

Transmission and Spread

The virus is present in great quantity in the blisters’ fluid, saliva, milk, dung and respired air. Contamination of any objects with any one or more of these discharges is a danger to other stock. At the height of the disease, virus is also present in the blood. FMD is found in all secretions and excretions that occur from infected animals. Airborne spread of this disease can also take place in which the infected animals breathe out a huge amount of aerosolized virus which infects other animals via oral or respiratory routes. The virus usually remains in milk and semen for about 4 days before the animal displays clinical signs of disease.

Animals get infected by the virus either by direct contact with a tainted animal, by contact with foodstuffs or other things which are already contaminated by such an animal, or by eating or coming into contact with an infected carcass. The disease is spread automatically by the movement of animals, persons, vehicles and other things which are contaminated by the virus. Trucks, Lorries, market places, and loading ramps where infected animals have travelled pose dangerous unless they are disinfected. Roads may also get contaminated and virus may get carried on the wheels of passing vehicles. The boots, clothing and hands of stockmen who have attended diseased animals may also spread the disease. Dogs, poultry, wild game, cats, and vermin may also pose as the infection carrier.

The significance of Foot and Mouth disease is related to how the virus spreads through any or all of the following:

Infected animals that have been introduced into a herd (carrying virus in their saliva, milk, semen, etc.);
contaminated pens/buildings, or animal transport vehicles;
contaminated materials such as feed, water, milk, hay, or biologics;
contaminated clothing, footwear, or equipment;
virus-infected meat or other contaminated animal products (if fed to animals in the raw or improperly cooked form);
Infected aerosols (virus spread from an infected property via air currents).

Animals that have recovered from infection may still carry the virus and lead to new outbreaks of the disease.

Effects of FMD

The disease is rarely found to be fatal, except in the case of very young animals, which may have a possibility of dying without showing any symptoms. In exceptional cases, a severe form of FMD may lead to sudden deaths among older animals.

The after effects of FMD are severe. Affected animals’ lose condition and secondary bacterial infections may extend their period of recovery. The most serious effects of the disease are seen in dairy cattle which includes loss of milk yield. Chronic mastitis may develop in the cattle leading to reduction in the cow’s value permanently. Abortion, sterility, chronic lameness and in some cases chronic heart disease occurs.

Public Health Risk

FMD is not readily transmissible to humans and does not hold a public health risk.

Symptoms

Fever
Loss of appetite
Quivering lips
Frothing of mouth
Blisters in mouth, teat and feet
Drop in milk production
Weight loss
Lameness

The severity of clinical signs depends on the strain of virus, the age and species of animal, the exposure dose, and the host immunity. Morbidity may be 100% in susceptible populations. Mortality is usually low in adult animals (1–5%), but higher in young calves, piglets, and lambs (20% or higher). The incubation period lies between 2–14 days.

Clinical signs can range from mild or in apparent to severe; they are usually found to be more severe in cattle and intensively reared pigs in comparison to sheep and goats.

In the infected animals, death can occur before development of blisters due to a multifocal Myocarditis. Myositis may also occur in others.

Treatment or Cure

As such, there is no specific treatment or cure for FMD. Affected animals recover with time. However, vaccines can protect against the disease but there is no confirmation that it will prevent animals from being infected. Infected animals are usually culled as a result of loss of production and infection due to FMD.

Prevention

FMD is considered to be one of the most difficult animal infections to control. As the disease occurs in several parts of the world, there always exists a chance of its accidental introduction into unaffected countries.

Export restrictions are often imposed on countries with known outbreaks of Foot and Mouth disease.

FMD outbreaks can usually be controlled by quarantines & movement restrictions, cleansing and disinfection of affected premises, equipment and vehicles, and euthanasia of affected & in-contact animals.

The implementation of the FMD control strategy differs from country to country and usually depends on the epidemiological situation of the disease:

In general, it is important for livestock owners and producers to sustain sound biosecurity practices in order to prevent the introduction and further spreading of the virus.

Measures that are recommended at the farm level to prevent FMD include:

controlling people’s access to livestock and equipment;
controlling the introduction of infected animals into existing herds;
monitoring and reporting of illness;
Regular cleansing and disinfection of livestock pens, buildings, vehicles and equipment;
proper disposal of manure and dead carcasses.

Contingency planning for potential outbreaks identifies the elements that are included in a response attempt to eradicate FMD, such as:

humane culling of all infected, recovered and FMD-susceptible contact animals;
proper disposal of carcasses and all animal produce;
examination and tracing of potentially infected or exposed livestock;
stern quarantine and controls on movement of livestock, equipment, vehicles, and;
comprehensive disinfection of premises and all infected materials such as implements, cars, clothes, etc.

Vaccination

Vaccination can be used to reduce the outbreak of FMD or protect animals.

Vaccines are also used in prevalent regions to protect animals from the disease. FMDV vaccines must be used after properly matching the serotype and strain of the infecting strain. It is vital to use inactivated virus vaccines, as these virus are incapable of multiplying in the vaccinated animals. The use of live virus vaccines is unacceptable as they carry the danger of reversion to virulence.

Vaccination with one serotype under no circumstances protect the animal against other serotypes, and does not carry any guarantee of protecting the animal completely or at all from other strains of the same serotype. Currently, there is no universal FMD vaccine as such.