This is a mild, systemic viral infection of cattle in the tropics causing generalised skin disease. Transmission is mainly by biting insects and the viral reservoir is cattle with latent infection. Outbreaks are mild, sporadic and occur in the wet season. The virus is identical to the bovine herpes mammilitis virus causing a separate syndrome of skin ulceration confined to the teats and udder. The skin lesions may cause rejection during selection. Confusion with ringworm or lumpy skin disease may cause concern during health inspections on arrival at destination countries.
Firm, round raised nodules with a flat surface and depressed centre appear suddenly all over the body but mainly on the head, neck, shoulders, back and perineum. Otherwise, the cattle are usually unaffected. After a week or two the lesions slough leaving 1-2cm circular patches of alopecia resembling ringworm and possibly dermatophilosis and stephanofilariasis. Lesions disappear in a few weeks when hair regrows.
Laboratory confirmation requires skin biopsies chilled for virology and in buffered formalin for histology.
Lumpy skin disease, caused by the more serious and exotic pox virus, is differentiated by it being a more severe illness with deeply ulcerative, necrotic skin lesions leaving permanent scarring. Dermatophilus congolensis may also cause skin nodules in cattle.
No treatment is necessary. Lesions will spontaneously heal over a few weeks.
No specific control other than general attention to control of biting insects and routine hygiene.