Foot and Mouth Disease - FMD

 Introduction

Foot-and-Mouth Disease is a viral disease caused by an Aptho virus.  This disease spreads rapidly among cloven-hoofed animals in breath, saliva, mucus, milk or faces.  It is a severe and highly communicable disease of cattle, pigs, sheep, goats and deer. 
The disease found in most parts of the world - the OIE lists at least 52 countries throughout Africa, the Middle East, Asia and South America that have reported the disease. There are seven serotypes of the virus: A, O, C, SAT1, SAT2, SAT3 and Asia1. These are further subdivided into more than 60 strains.

Clinical signs and symptoms

The disease is characterized by blister-like lesions on the tongue, nose and lips, in the mouth, on the teats and between the toes which then burst, leaving painful ulcers.   The blisters cause a heavy flow of sticky, foamy saliva that hangs from the mouth.  Infected animals sway from one foot to the other due to the tenderness of the feet.  Although older cattle usually do not die from the infection, they suffer a severe illness which leaves them in a weakened state. 

• Fever
• Bilsters in the mouth and on feet
• Drop in milk production
• Weight loss
• Loss of appetite
• Quivering lips and frothing of mouth
• Cows may develop blisters on teats
• Lameness

Transmission

The virus is extremely contagious and spreads rapidly unless it is contained.  It can also be spread on wool, hair, grass or straw, by the wind or by mud or manure sticking to footwear, clothing, livestock equipment or vehicles, as well as most commonly through the movement of infected animals. Therefore, it usually requires quarantining infected farms, followed by slaughtering and burning all susceptible animals. Anyone having contact with animals in infected countries should not go near susceptible animals for at least five days. 

Pigs are regarded as amplifying hosts as they can excrete large quantities of the virus in their exhaled breath. Cattle are able to be infected by breathing in small quantities of the virus. The virus can be excreted by animals for up to four days before clinical signs appear and some animals can continue excreting the virus for long periods after apparent recovery.

FMD spreads rapidly especially in cool, damp climates or when animals are penned or housed in cold weather. The virus survives well at temperatures below 4 degrees celcius, but is inactivated as temperatures rise. It is also rapidly inactivated at relative humidity less than 60 per cent.

Treatment

No treatment is given. Affected animals may recover. However because of the loss of production and the infectious state of the disease, infected animals are usually culled.

Prevention

FMD is one of the most difficult animal infections to control. Good bio-security measures should be practiced on uninfected farms to prevent entry of the virus. Because the disease occurs in many parts of the world, there is always a chance of its accidental introduction into an unaffected country.  Export restrictions are often imposed on countries with known outbreaks.
FMD outbreaks are usually controlled by quarantines and movement restrictions, euthanasia of affected and in-contact animals, and cleansing and disinfection of affected premises, equipment and vehicles.
Infected carcasses must be disposed of safely by incineration, rendering, burial or other techniques. Milk from infected cows can be inactivated by heating to 100°C (212°F) for more than 20 minutes. Slurry can be heated to 67°C (153°F) for three minutes. Rodents and other vectors may be killed to prevent them from mechanically disseminating the virus.

Vaccination

FMD vaccine is a killed preparation and, at best, affords good protection against challenge for 4-6 months.

Vaccination with one serotype does not protect the animal against other serotypes, and may not protect the animal completely or at all from other strains of the same serotype. Currently, there is no universal FMD vaccine.

Human Transmission

Human infections have been reported but they are very rare and do not result in serious disease. Humans can carry the virus in their nose for up to 24 hours and can be a source of infection for animals.

Human foot and mouth disease affects the inside of the mouth, the palm of the hands, fingers and soles of the feet, mostly in children. Typical symptoms include a rash or ulcers in the mouth, on the inner cheeks, gums, sides of the tongue, and bumps or blisters on the hand, feet and sometimes other parts of the skin which may last seven to 10 days. Seek medical attention if you think you or your child may be affected.

Human foot and mouth diseases are quite different and are caused by different organisms. Viruses from the group called enteroviruses cause HFMD. FMD in livestock is not a threat to human health.