Infection is transmitted by direct contact between infected domestic and wild animals and susceptible livestock; by arthropod vector (Phlebotomus, Aedes and Culicoides etc.); mechanically by equipment such as teat cups and harness bits, via drinking water or feed contaminated with infected saliva and vesicular fluid. In endemic areas, the virus is maintained by transmission cycles between insects and wild mammals. The primary routes of human infection are the respiratory tract via infective aerosols
Clinical signs: The incubation period is 1-3 days. The earliest clinical signs include fever and loss of appetite, excessive salivation, difficulty in eating, lip smacking and lameness. Thin-walled, isolated or coalescing vesicles (blisters) may appear on the tongue, lips, gums, coronary bands, interdigital skin, or teats near the teat orifice. The vesicles readily rupture and resulting ulcers usually heal over the next 8-10 days. Morbidity is very variable but can be up to 100%. Mortality is low. In horses the turbinates, nasopharynx and larynx may be affected, resulting in nose bleeding and difficulty in eating and breathing. Coronary band lesions can lead to deformity and sloughing of the hoof. Lesions can occur on the udder or prepuce.
Diagnosis: Laboratory tests such as electron microscopy and ELISA can rapidly detect viral antigens and can provide a diagnosis within 4 hours. Tissue cultures (chick fibroblast, pig kidney, Vero and BHK-21), suckling mice or embryonated eggs can be used for virus isolation and subsequent characterization. Indirect sandwich ELISA is method of choice for virus serotyping. Serological tests including serum neutralization, complement fixation and competitive ELISA are useful for detection of antibodies.
Prevention and control: Judicious slaughter of clinically affected animals, quarantine and movement controls on animal, animal products and things from disease declared areas will prevent spread of infection. Disease surveillance determines the source and extent of infection and provides proof of freedom from the disease. Vector control is required to protect valuable individual animals in declared areas and to reduce further transmission. Attenuated and inactivated vaccines have been tested with unknown efficacy. No commercial vaccine is as yet available. There is no cross-immunity between serotypes.