Foot and mouth disease is a highly communicable disease affecting cloven footed animals and is characterized by fever, formation of vesicles and blisters in the mouth, udders, and teats and on the skin between the toes and above the hooves. Animals recovered from the disease, present a characteristically rough coat and deformation of the hoof. In India, the disease is not serious for livestock and seldom progresses to a fatal issue, but it occurs practically all the year round and, being widespread, it assumes a position of importance in livestock industry. The annual economic loss on account of this disease is estimated to be about Rs. 2.5 crores. The disease affects mostly cattle and pigs of all breeds and ages. Imported cattle and cross-bred suffer more severely, with a mortality rate of 10 to 20 percent, against only 2 to 3 per cent in the local breeds. Although buffaloes, sheep and goats are also susceptible to the disease, they are seldom affected. Under experimental condition, goats have been found to be more susceptible than sheep.
The disease spreads very commonly by direct contact or, indirectly, through infected water, manure, hay and pastures. It is also conveyed by cattle attendants through their clothes or through their hands when the latter have been recently used in milking affected animals. It is known to spread through recovered animals, field rats, porcupines and birds, while improperly sterilized canned meat may also be a vehicle of the infection. Foot-and-mouth disease occurs in a relatively mild form in India, where the disease has been existing for years and where, in view of the frequent opportunities for natural infection, the bulk of the livestock acquire a greater degree of resistance to the disease. It occurs in a virulent form in U.S.A. and United Kingdom and other European countries, where new and susceptible animals are a I lacked a I each mil-break of the disease.
The virus and its characters:
The virus occurs in a high concentration in the lesions of the mouth, feet and udder. At the height of temperature the virus is present in the blood in a low concentration and becomes soon localized in vesicles in the parts of the body mentioned above.
The virus gains entry into the circulating blood of animal through injury in the lining membrane of the mouth, tongue, intestines, clefts of hooves and other similar parts. The incubation period in natural infection is about two to five days. In artificial infections, the temperature rises to 104 to 105°F. In about 24 to 48 hours and at this stage the virus occurs in the circulation, being eventually carried to distant parts of the body, where it causes the formation of vesicles.
Diagnosis: Its quick spread and the occurrence of lesions in the feet of affected animals are characteristics of the foot-and-mouth disease. It presents some similarity to Rinderpest from which, however, it is readily differentiated by the absence of diarrhoea and by the presence of foot lesions. Confirmation of the diagnosis may, where possible, be obtained by the intradermal inoculation of vesicular fluid or a suspension of vesicular epithelium into guinea pigs which, as a result of such inoculation, usually develop characteristic lesions of the disease.
No scientific evidence is obtainable in support of claims that foot and mouth disease is curable by the use of therapeutic agents. The use of drugs by field workers is only resorted to as a measure of aiding in the natural process of recovery. Thus, the external application of antiseptics contributes lo the healing of the ulcers and wards off attacks by flies. A common and inexpensive dressing for the lesions in the feet is a mixture of coal tar and copper sulphate in the proportion of 5: 1.
Control and prevention:
Prevention is known to be the only dependable method of dealing with foot-and-mouth disease. In countries where the disease does, not exist or where its incidence is very low, legislatie action has been taken to make it obligatory to notify all suspected cases of foot-and-mouth disease. The usual measures adopted in these countries consist in the slaughter of all affected and in-contact animals, a thorough disinfection all utensils and clothes of attendants and a strict watch over animals in the neighboring areas. The slaughtered animals are buried lo a depth to list five feel in the ground and covered with lime and earth. The affected premises are not used for at least 30 days, and are tested for infectivity at the end of this period by allowing small groups of animals into them to commence with.