Foot and Mouth Disease
No farmer wants to have any Aphtae epizooticae in his barn. That long name is the one that scientists use when they talk about a particular virus—the virus that causes Foot and mouth disease. Some scientists shorten that name, and refer to A. epizooticae. Farmers sometimes use an even shorter designation for the associated viral infection. They call it “FMD.”
Foot and mouth disease can spread easily among a herd of cloven-hoofed animals. Farmers know that any animal that contracts FMD could die. Farmers want to keep any possible source of A. epizooticae out of their barns, because so many farm animals, such as sheep, goats, pigs and cows, have cloven hoofs.
Scientists who study FMD do not want to bring a large farm animal into a lab. Therefore, they infect mice, rats and chickens with the virus that causes FMD. While those small animals can acquire FMD through an injection, one administered in a laboratory, those small animals can not contract that dread disease.
Pet animals such as dogs and cats have been known to enter and even sleep in barns. Could a pet get FMD? No, a dog or cat would never contract FMD, but either of those domesticated animals could carry the FMD virus in its fur. Such a pet could then carry that virus into the barn, and could thus infect one group of farm animals.
What happens when a cloven-hoofed animal gets FMD? For what symptoms does a farmer need to watch? A farmer should be concerned about a possible FMD infection if one or more of the barn animals have a high fever, one that declines rapidly after a period of two to three days. Other “alarm signals” include the following: blisters inside the mouth, excessive secretion of stringy or foamy saliva and blisters on the feet. Sometimes, too, an animal with FMD suffers from a marked weight loss.
How farmers reduce the chances that an FMD causing virus might get into any of their barns? In addition to wiping down any household pets, farmers need to limit the use of spray cans inside their barns. An aerosol spray can carry the FMD virus. Farmers should also try to keep any type of motored vehicle out of their barns. Uncooked food scraps and feed supplements provide the FMD causing virus with yet another “cozy” place to “wait out” any period away from a truly hospitable environment.
What factors invite growth and reproduction of the FMD causing virus? That tiny virus is a shell of protein, a shell that surrounds a single strand of RNA. That virus looks for an opportunity to make contact with a host cell. It binds to a specific receptor site, and causes the cell membrane to fold inward. As a result, the virus enters the cell. At that point, the protein coat on the virus dissolves, and the exposed RNA starts to make more viral RNA.
Eventually, the infected cell bursts, releasing an entire “colony” of infectious virus. Only the vaccination of farm animals can hold off the aforementioned chain of events.