Source: WOAH
Subject: Science and Technology
Context: The World Organisation for Animal Health (WOAH) has issued an urgent call to action following the unprecedented international spread of Foot-and-Mouth Disease (FMD) serotype SAT 1.
About Foot-and-Mouth Disease (FMD):
What it is?
- Foot-and-Mouth Disease is a highly contagious viral disease affecting cloven-hoofed animals, including cattle, pigs, sheep, goats, and various wildlife species like buffalo and deer.
- It is caused by an aphthovirus of the Picornaviridae While it is rarely fatal in adult animals, it causes severe production losses and is a major barrier to international trade.
Vectors and Transmission:
The virus is notorious for its impressive endurance and ability to spread rapidly through multiple pathways:
- Direct Contact: Between infected and susceptible animals via saliva, urine, dung, or fluid from ruptured blisters.
- Mechanical Vectors: Humans can carry the virus on their clothes, boots, and skin; vehicles, tyres, and farm equipment also act as major vectors.
- Infected Products: Uncooked food scraps, milk, or biological materials (like semen) containing the virus can trigger new outbreaks.
- Airborne Spread: In certain climatic conditions, the virus can be carried by the wind over long distances from one farm to another.
How it Spreads?
- The current international crisis (SAT 1) is primarily driven by unregulated animal movements and informal trade networks.
- Markets and holding areas where animals from different sources congregate serve as high-risk mixing points where the virus amplifies before being transported to new regions.
Key Features of the Disease:
- Clinical Signs: Characterized by high fever followed by the development of vesicles (blisters) on the tongue, lips, mouth, and between the hooves.
- Morbidity: Affected animals suffer from lameness, excessive salivation (slobbering), and a dramatic drop in milk yield.
- Sudden Death in Young: While adults survive, young calves, lambs, and piglets may die suddenly due to myocarditis (inflammation of the heart muscle).
- Serotype Specificity: There are seven distinct serotypes (O, A, C, SAT 1, SAT 2, SAT 3, and Asia 1). Immunity against one serotype does not protect an animal against others.
- Carrier State: Ruminants (like cattle and buffalo) can become carriers, harboring the virus in their throat for months even after recovery.
Treatment:
There is no curative treatment for FMD once an animal is infected. Management focuses entirely on prevention and control:
- Vaccination: Using serotype-specific inactivated vaccines to build herd immunity.
- Biosecurity: Strict movement controls, disinfection of vehicles, and quarantine of new stock.
- Culling: In many regions, the stamping-out policy (culling all susceptible animals on an affected farm) is used to break the transmission cycle.
