Epidemiology of heartwater in Guadeloupe and in the Caribbean.

At present, heartwater in the Caribbean is known with certainty only on Guadeloupe, Marie Galante and Antigua; the first 2 islands are widely infected. The most important factors responsible for particular aspects of heartwater in Guadeloupe are: Cowdria ruminantium of high virulence. A very resistant cattle population (Creole), not normally clinically affected. A fairly susceptible goat population (Creole) (22% goats born in endemic areas die after experimental inoculation) which, fortunately, includes breeding lines with inherited resistance characteristics. Amblyomma variegatum which is present all over the island and all through the year, but with a low infection rate (1-2% of adult ticks are infected) because of the short period of rickettsemia in infected animals. The low rate of tick infection results in a low endemicity of the disease. For goats, the epidemiologic situation can be regarded as unstable because the low rate of infection in ticks does not allow a natural immunization of the majority of young kids when they still have a non-specific resistance. The possible evolution of heartwater in the Caribbean and in the United States in considered.