Serologic evidence for the etiologic role of Chuzan virus in an epizootic of congenital abnormalities with hydranencephaly-cerebellar hypoplasia syndrome of calves in Japan.

An epizootic of congenital abnormalities of calves was observed in the Kyushu district of Japan from November 1985 through April 1986. The main clinical signs of the disease were impairment of mobility and signs of impairment of the nervous system. Opisthotonos was pronounced, and almost all calves were unable to suckle by themselves. The main macroscopic pathologic changes were hydranencephaly and cerebellar hypoplasia. Although an etiologic agent was not isolated from the calves, serotest results of precolostral serum samples indicated that 128 of 139 (92%) abnormal calves had antibody for Chuzan virus, a new virus belonging to the Palyam subgroup of the Orbivirus genus; 34 healthy calves in the epizootiologic area did not have antibody for the virus. The presence of Chuzan virus in Kyushu in 1985 was confirmed serologically.