PROPAGATION OF THE TICK AMBLYOMMA-VARIEGATUM IN THE CARIBBEAN

The tropical bent tick Amblyomma variegatum, is an African tick specie s which infests livestock and wildlife. It was probably introduced in the central eastern islands of the Caribbean during the 18th or 19th c entury, with cattle shipped from Senegal. In Africa and the Caribbean, this tick is a vector of heartwater (a rickettsial disease of ruminan ts) and is associated with acute dermatophilosis (a bacterial skin dis ease of animals). Until 1948, only Guadeloupe and the neighbouring isl ands of Marie Galante and Antigua were infested with this tick species . Following increased agricultural commerce between Guadeloupe and Mar tinique, the latter became infested in 1948. Between 1967 (when the ti ck was identified in St Croix) and 1988 (when a male tick was reported in St Vincent), fourteen new islands were reached by this tick. Most of the dissemination of the tick to new islands cannot be explained by legal or illegal movements of livestock. Recently-determined circumst antial evidence strongly links the increase in populations of the catt le egret (Bubulcus ibis), a migrating bird established in the Caribbea n circa 1960, with increased colonisation of new islands by A. variega tum. Considering the wide range of areas currently occupied by this bi rd species in the Greater Antilles and on the American mainland, there is a high probability that the tick will also expand its range a,ln i nvade new, areas Eradication of A. variegatum from the Caribbean and t hus from the western hemisphere, and the strengthening of measures To prevent inter-island movements of livestock, would be the only effecti ve means of preventing this threat.