BLUETONGUE VIRUS ISOLATIONS FROM VECTORS AND RUMINANTS IN CENTRAL-AMERICA AND THE CARIBBEAN

A regional prospective study of the epidemiology of bluetongue virus ( BTV) serotypes covering 11 countries in Central America and the Caribb ean took place between 1987 and 1992. Active surveillance revealed BTV infection to be endemic in the absence of confirmed indigenous cases of bluetongue. During the 6-year span of the study, over 300 BTV isola tions were obtained from cattle and sheep. Results df the earlier year s of the study were summarized, and surveillance activities in the con cluding months of the study from November 1990 to February 1992 were e valuated. Forty-five BTV isolations were made during this time, 44 fro m sentinel cattle and 1 from a ram with clinical signs compatible with contagious ecthyma. Virus isolation from potential vectors also was a ttempted, yielding a further 9 BTV isolates from parous Culicoides ins ignis and C pusillus, 2 BTV isolates from blood-engorged C filarifer, and 1 epizootic hemorrhagic disease virus type-2 isolate from parous C pusillus. Our extensive network of sentinel herds in the region detec ted BTV-1 as the predominant serotype in Central America in 1991, afte r an apparent absence of 1 year in the sentinel animals. Other serotyp es in Central America at that time included BTV-3 and BTV-6. In Puerto Rico and the Dominican Republic, BTV-4 became the predominant serotyp e, without detection of BTV-8 and BTV-17, which were common in recent years of the study, The serotypes found in the Caribbean Basin continu ed to have marked differences from those in North America. The importa nce of viewing bluetongue as an infection, the distribution of which i s determined principally by ecologic factors, is emphasized.