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Epidemiology of heartwater in Guadeloupe and in the Caribbean
Insights
Heartwater disease in the Caribbean, particularly Guadeloupe, is influenced by virulent Cowdria ruminantium and tick vectors. Cattle resistance and goat susceptibility, coupled with low tick infection rates, create an unstable epidemiologic situation for heartwater.
Area of Science:
- Veterinary Medicine
- Infectious Diseases
- Epidemiology
Background:
- Heartwater, caused by Cowdria ruminantium, is confirmed in Guadeloupe, Marie Galante, and Antigua.
- Guadeloupe exhibits high virulence of Cowdria ruminantium, a resistant Creole cattle population, and a susceptible Creole goat population.
Purpose of the Study:
- To analyze the key factors influencing heartwater epidemiology in Guadeloupe.
- To assess the disease's potential evolution in the Caribbean and the United States.
Main Methods:
- Epidemiological analysis of heartwater in Guadeloupe.
- Evaluation of host resistance (cattle, goats) and vector (Amblyomma variegatum) infection rates.
Main Results:
- Low tick infection rates (1-2%) due to short rickettsemia periods contribute to low heartwater endemicity.
- Goat populations face unstable epidemiology, hindering natural immunization in young animals.
- Creole cattle show high resistance, while Creole goats exhibit susceptibility but possess resistant breeding lines.
Conclusions:
- The interplay of virulent pathogens, resistant hosts, susceptible hosts with resistant lines, and low vector infection rates shapes heartwater's epidemiology in Guadeloupe.
- The unstable epidemiological situation in goats poses a risk for natural immunization.
- Further consideration of heartwater's potential spread in the Caribbean and USA is warranted.
Abstract:
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.