What are the symptoms of foot-and-mouth disease in cloven-hoofed animals such as pigs, and can it be transmitted to humans?

Foot-and-mouth disease, also called “aphthous fever” or “pihuang,” is an acute, febrile, highly contagious infectious disease of cloven-hoofed animals caused by the foot-and-mouth disease virus. It mainly affects cloven-hoofed animals, is occasionally seen in humans and other animals, and absolutely does not infect other livestock or poultry such as chickens and ducks. Its clinical features are blisters on the oral mucosa, hooves and skin of the udder. The specific symptoms are as follows:

1. Sick cattle stand still and drool, sick pigs lie on the ground unable to rise, and sick sheep walk on their toes;

2. Blisters appear on the lips, tongue surface, gums, nose mirror, heel of the hoof, interdigital space, udder and other parts;

3. In the later stage of the disease, the blisters rupture and scab over; in severe cases the hoof shell falls off, and during recovery scars and new hoof horn can be seen;

4. Foot-and-mouth disease spreads quickly and has a high incidence rate; adult animals have a low mortality rate, while young livestock often die suddenly with a high mortality rate, and piglets often die whole litters at a time.

Appendix: Can pigs' “foot-and-mouth disease” be transmitted to humans?

Humans may contract foot-and-mouth disease through contact with infected animals, but this situation is very rare. Because the foot-and-mouth disease virus is sensitive to gastric acid, humans usually do not become infected with the foot-and-mouth disease virus by eating meat. In the United Kingdom, the last confirmed human case of foot-and-mouth disease was in 1967. In continental Europe, Africa and South America there have also been only very few cases of infection. The symptoms of human infection with foot-and-mouth disease include discomfort, fever, vomiting, red ulceration and decay of oral tissues (superficially erosive blisters), and occasionally small blisters on the skin. For humans, it is worth noting that these symptoms are similar to those of another viral disease, commonly called “hand, foot and mouth disease,” which occurs more frequently in humans, especially young children; that disease is caused by another virus in the Picornaviridae family, an enterovirus called Coxsackie A virus. Because foot-and-mouth disease rarely infects humans but spreads among animals at a very fast rate, its harm to the agricultural and livestock industry is much greater than its harm to human health. Farmers around the world may suffer losses of up to 1 billion US dollars in a year when a foot-and-mouth disease epidemic occurs, and it will also lead to the destruction of large numbers of livestock as well as a huge reduction in income from milk and meat products.

Appendix 2: Foot-and-mouth disease is harmless to humans, so why must pigs still continue to be culled?

For pig farms where foot-and-mouth disease occurs, the reason the whole farm must be culled is mainly that the ”foot-and-mouth disease” virus spreads very rapidly, and in addition Taiwan, China has not had an outbreak of foot-and-mouth disease for at least 70 years, so all existing pigs being raised have no resistance to foot-and-mouth disease. Before the imported supply of foot-and-mouth disease vaccine can fully provide injections for all pigs, in order to spare other pig farms that have not yet had ”foot-and-mouth disease” from infection and major economic losses, all pigs on the affected farm must be culled to reduce the spread of the virus and help control the epidemic.