Zoonotic and emerging orbivirus infections

Many novel emerging orbiviruses have been isolated in the past 15 years. Important viruses include Peruvian horse sickness virus (PHSV) and Yunnan orbivirus (YUOV), pathogens of equids which were originally isolated almost simultaneously from 1997 to 1999 in the People's Republic of China, Australia and Peru. YUOV has also been isolated from cattle, sheep and a dog. The isolation of YUOV from a dog is not the first case of an orbivirus being isolated from a carnivore. Bluetongue virus and African horse sickness virus were earlier detected in carnivores which fed on contaminated meat. PHSV and YUOV both offer an opportunity to study the emergence of a single pathogen in geographically distant locations, although the original point of emergence is still unidentified. PHSV has been isolated form horses with neurological disease both in Australia and in Peru (where it is now endemic). Serological and molecular diagnostic assays have been developed for these viruses to assist in their identification and diagnosis. Other orbiviruses, such as Palyam virus and equine encephalosis virus, have more recently been identified outside their geographical boundaries and may represent a threat to domesticated livestock and horses, respectively. The article also reviews four zoonotic orbivirus species (Corriparta virus, Changuinola virus, Kemerovo virus and Orungo virus) which have been identified in livestock and/or wildlife.