Risk factors associated with tick infestation and Ehrlichia ruminantium amongst cattle in Guadeloupe, French West Indies.

Abstract

Ehrlichia ruminantium infection and infestations by two tick species, Amblyomma variegatum and Rhipicephalus microplus, are a major threat to the livestock sector in Guadeloupe. This study examined specific tick infestations for 261 cattle from 73 farms on the archipelagos three largest islands, Basse-Terre, Grande-Terre and Marie-Galante. A questionnaire was implemented to gather information on farming practices and livestock characteristics in order to identify potential risk factors associated with the presence of antibodies against E. ruminantium and the abundance of ticks in livestock. A total of 81% of the inspected cattle were found to be infested with ticks, with a prevalence of 69% for A. variegatum and 47% for R. microplus. At farm level, 96% of farms had infested animals, 84% of which were infested with A. variegatum and 73% with R. microplus. Risk factors were first explored using multiple correspondence analysis (MCA) followed by a generalized linear model at the farm level, and finally a generalized linear mixed model at cattle level. MCA revealed that non-traditional breeding system, with free-grazing animals, were associated with serological evidence of E. ruminantium circulation and also higher tick infestations. The utilisation of green fodder had a significant impact on the prevalence of seropositive animals and tick abundance. Differences in infestation were observed between the three largest islands of Guadeloupe and have been discussed in this article. The frequency of acaricide bathing and its interaction with acaricide alternation appeared to be significant factors in the mitigation of tick infestations in cattle. However, this study highlights the potential emergence of acaricide resistance within tick populations in Guadeloupe.