Bluetongue virus in South America: overview of viruses, vectors, surveillance and unique features.

Since the first published report of bluetongue (BT) virus (BTV) infection in South America from Brazil in 1978, serological surveys have determined that the infection is widespread in sheep, cattle, goats and water buffalo but generally without clinical signs. Only four outbreaks of BT disease have been reported so far in Brazil. Brazil and Argentina are the only countries in South America where BTV serotypes 12 and 4 have been isolated, respectively. By serology, serotypes 4, 6, 14, 17, 19 and 20 were detected in Brazil, 12, 14 and 17 in Colombia, 14 and 17 in Guyana and 6, 14 and 17 in Suriname. Culicoides insignis is the predominant vector in the area, but C. pusillus could also be a BTV vector. The virus has not yet been isolated from the vector in the region.