Background

Foot-and-mouth disease virus (FMDV) is grouped with the genus Aphthovirus belonging to the family Picornaviridae . Seven different serotypes of FMDV have been identified as types A, O, C, South African Territories (SAT) 1, SAT 2, SAT 3, and Asia 1. Previous vaccination or infection in animals with one serotype does not protect other serotypes, and within a serotype, various strains further reduce the vaccine efficiency. Currently, the disease is enzootic all over the world except Australia and North America. The distribution of the seven serotypes of FMDV is not uniform across the globe. However, few countries like Australasia, North and Central America, Europe, Greenland, and Oceania are considered as free from FMD. FMDV causes disease in domestic cloven-hoofed animals like cattle, sheep, goat, swine, deer, and more than 70 other species of wild animals. The disease is characterized by fever, vesicular lesions on feet, tongue, snout, and teats, and lameness. The goat and sheep show mild symptoms of the disease and cannot be distinguished from other general conditions. The FMDV is highly contagious, has a wide host range, rapid replication rate, and various routes of transmission make FMD rare and severe disease to eradicate and control. Thus, FMD is a significant barrier in the international trade of animals and animal products. The FMD infection has an impressive capacity to spread the disease over long distances in the disease-free area. FMD, a highly contagious disease of animals and humans, replicates rapidly and spreads by direct contact with susceptible animals or by aerosols. The symptoms of the disease appear within 2-3 days and remain for up to 7-10 days. According to the Office International des E´pizooties (OIE), FMD is a list A infectious disease hindering international trade of livestock and animal products. Countries, which are free from infection, have taken several steps to avoid the Smoot-Hawley Tariff Act of 1930, which restrict the import of susceptible livestock, and animal products from FMD infected countries. The FMD is generally controlled by vaccine prepared by the inactivated whole virus and formulated with adjuvant before field use.

Cause

A viral disease caused by Aphthovirus/Picornavirus (serotype O, A, C and Asia 1)

Host Species

All cloven footed (a hoof split into two toes) animals: Cattle, buffalo, sheep, goat, pigs, camel and some wild animals

• The disease spreads by ingestion of virus contaminated feed and water.
• Direct contact between infected and healthy animals moving within the herd.
• Airborne transmission occurs according to the direction of wind.
• The disease can spread by inhalation as virus remains active in aerosol form for long periods in temperate or subtropical climates.
• In artificial insemination, the disease may spread to healthy cow through infected semen.
• The carrier animals after clinical recovery are also the potential source of infection.

Cattle and buffalo

• High rise of body temperature, loss of appetite and sudden drop of milk yield
• Appearance of vesicles on mouth including tongue leads to profuse salivation from acute painful stomatitis.
• Rupture of vesicles of feet and marked painful swelling of the coronet cause acute discomfort and the animal shows lameness on walking.
• In absence of antiseptic dressing, maggot infestation occurs on hooves.
• Finally animals become recumbent.
• When vesicles appear on udder, mastitis develops.
• Abortion is also possible in advanced pregnant animals.
• Sudden death occurs in young animals.
• Post FMD complex: After recovery of FMD, a chronic syndrome of dyspnea, panting, anemia, overgrowth of hair and lack of heat tolerance is observed. Diabetes mellitus is also observed as a sequel in cattle.

Sheep and Goat

• The symptoms are generally mild in nature in sheep and goats.
• Adult sheep may develop a syndrome identical to that of Cattle so that it becomes a crippling disease with occasional loss of hooves from bacterial complications.
• In goats, the more common symptom is appearance of few, small lesions, but with moresevere involvement of all four feet.
• As in cattle, kids and lambs are more vulnerable.

Pig

• In pigs, the syndrome may be manifested as devastating form.
• Large vesicles and bullae occur in the snout and feet and these may rupture to expose large, raw surfaces. The hooves of pigs become detached resulting into lameness and recumbent.

Management

Therapeutic management is as follows:

Non-steroidal anti-inflammatory drugs (NSAID) are used to alleviate fever and pain.

• Large doses crystalline penicillin should be administered large doses (40000 IU/kg BW) intravenously followed by longer acting preparations.
• Surgical debridement of the lesions, including fasciotomy, is indicated if the animal is not moribound.
• Dressing of wounds with 0.01 to 0.02% potassium permanganate solution three to four times /day followed by topical spray preparations
• Administration of multivitamin preparations to accelerate the healing process of epithelial cells

Preventive measures

• In enzootic area, annual vaccination of all cattle between 3 and 6 months with two vaccinations given 4 weeks apart followed by an annual booster vaccination is recommended.
• This should be done just prior to the anticipated incidence period, before monsoon and summer.
• In an outbreak, all unaffected cattle should be vaccinated immediately and injected with penicillin at a dose of 10000 IU/ kg BW intramuscularly.
• Movement of the cattle is to be restricted from the affected pasture.
• In enzootic area, the ewes should be vaccinated twice and the last vaccination is given about 1 month before lambing.
• The vaccination before lambing will protect lambs against umbilical infection at birth or infection of the tail wound at docking in young age.
• If an outbreak of FMD is suspected ewes at lambing time, prophylactic injections of penicillin will prevent the disease.

Control

Regular vaccination is the only effective way to control the disease.

Type of vaccines

Inactivated vaccine (Aluminum hydroxide gel or oil adjuvant)

Combined vaccine is also available

Vaccination schedule

First vaccination is done at 5-6 months of age followed by booster after 6 months and to be repeated annually interval.

Dose

2/3/4/5 mL S/C or I/M route or according to manufacturer's instructions: 2/3/4/5 mL S/C or I/M route or according to manufacturer's instructions

Note: Deworming is must at least 15 days before vaccination.

Source/manufacturer of vaccine in India

Bio Vet. Pvt. Ltd., Karnataka

Indian Immunologicals, Hyderabad

Brilliant Bio Pharma Ltd., Hyderabad

Biomet. Pvt. Ltd., Ghaziabad (UP) Institute of Veterinary Biologicals, Pune, Thiruvananthapuram