Bluetongue and other orbiviruses in South America: gaps and challenges.

Abstract

South America (SA) has the ideal climatic conditions for occurrence of Bluetongue virus (BTV) and other orbiviruses. Based on serological evidence of BTV circulation, the virus is widespread across SA. However, little knowledge has been acquired about BTV origin and distribution, and circulation of specific serotypes is almost non‑existent. The first barrier to a better understanding of Bluetongue (BT) in SA concerns its recognition in the field, as most infections of seropositive ruminants are unapparent in endemic areas. There are few reports on BTV isolation in SA, many of them from viraemic asymptomatic animals. Among the known competent BTV vectors, Culicoides insignis is the most abundant species in SA. However, information about biological characteristics and competence of various other Culicoides species described in SA is missing. The few reports on BT outbreaks lead to an underestimation of the disease impact on the continent economy. To overcome these major gaps, it is necessary to: improve diagnostic structure and disease recognition in the field; identify BTV serotypes and their distribution in different SA areas; and to study the biology and epidemiology of Culicoides. Furthermore, it is important to have a surveillance system for BT, as well as contingency plans for possible outbreaks in SA.