Serological observations on the epidemiology of bluetongue virus infections in the Caribbean and Florida.

Serological surveys of cattle, sheep and goats have confirmed that infection with bluetongue virus (BTV) is common in Florida, Puerto Rico and St. Croix in the USA, in the Caribbean countries of Jamaica, St. Kitts/Nevis, Antigua, St. Lucia, Barbados, Grenada, Trinidad and Tobago, and the Bahamas, and in the South American countries of Guyana and Suriname. In most countries, over 50% of ruminant livestock have antibody to BTV as assessed by the bluetongue immunodiffusion (BTID) test. A sentinel animal system operating in Florida and 4 islands in the Caribbean has established that the transmission of BTV is seasonal, with most animals becoming infected in late summer and fall. In Florida, it appears that there may be some years when little virus transmission occurs among cattle. Examination of sera from yearling animals and sentinels in the region for antibody to the range of serotypes of BTV recognized worldwide, has resulted in a) the isolation of BTV type 2 from cattle in Florida - the 1st time this virus has been identified in the Western Hemisphere - and b) the recognition that the range of serotypes of BTV present in the Caribbean may be different from those in the USA. No clinical disease has been associated with BTV during the period of these studies (1979-83).