Investigation of an outbreak of sheeppox among native sheep breeds in the Western Himalayas of India.

Abstract

An outbreak of sheeppox was investigated in a cluster of villages situated in Western Himalayan ranges of a Northern Indian state. Non-migratory sheep (n = 80) of native breeds namely Gaddi and Rampur Bushair were infected and 15 have died. The outbreak started after a few animals contracted the disease during the summer grazing period at the highland pastures from migrating flocks of sheep. This initial outbreak resulted in a further spreading of the disease into the valley. Clinical examination revealed varying degree of cutaneous papular lesions and respiratory distress. Upon necropsy, visceral lesions in the lungs, trachea and kidneys were also found. Clinical and morbid samples were found positive for sheeppox virus using group specific P32 gene and I3L gene based multiplex PCR differentiating sheeppox and goatpox viruses. Histopathological, hematological and blood biochemical analysis also supported the pathology of an acute viral infection. The causative sheeppox virus strain was isolated using lamb testicular cell culture and phylogenetic analysis, based upon P32 and RPO30 genes, showed its clustering with other Indian strains reported from neighboring states. This study demonstrated the spread of sheeppox virus to new niches by migratory sheep flocks leading to establishment of endemic infections in many new pockets of higher Western Himalayas.