A Persistent Hog Cholera Viremia in Young Pigs.

Abstract

A persistent hog cholera viremia was produced in pigs that were 6 weeks of age from non-immune mothers but was not produced in pigs that were 3 months of age or in pigs that were 6 weeks of age from immune mothers. Although a similar condition of immunological tolerance has been reported for other animals, it was produced either in utero or shortly after birth. These pigs, therefore, appear unusual because persistence of virus was established at an older age. Pigs with persistent viremia failed to grow and showed elevated temperatures but survived for periods from 6 to 17 weeks. During this interval, persistent virus reverted to a fully virulent state. When stunted pigs became moribund, virus titers obtained from their spleens ranged from 107 to 109, in contrast to 105 found in spleens from moribund pigs infected in the usual manner with virulent virus. The ability of hog cholera virus to transmit in utero and to persist in pigs after birth may have epidemiological implications.