Bovine Dermatophilus congolensis infection in the French West Indies. II. Factors related to animals

Abstract

A study concerning 573 head, bred in infected environment was carried out in the French West Indies, in view of a better location of individual factors favouring the outbreak and the evolution of the disease. Animal susceptibility differs greatly in Guadeloupe from that in Martinique and extrinsic and intrinsic factors do not lead to the same effects in each island. Nor the breed can only explain the pathological phenomenon, except if the animals’ epidemiological background and, particularly the length of the co-evolution with A. variegatum, are to be taken into consideration. Guadeloupe Creole cattle have been in contact with the tick for a long time and only 5 % from examined animals are infected. In Martinique however, Creole cattle, more recently exposed to infestation, is extremely susceptible and 82 % of the studied animals are infected. Such a difference in receptivity is a consequence of the natural selection. In both islands, the disease incidence in recently imported exotic animals ranges 38 to 84 %. Even a low infestation with A. variegatum induces dermatophilosis in the very sensitive cattle of Martinique, while in Guadeloupe a proportional relationship between the infestation level and the infection probability is to be found. In Guadeloupe, breed and profusion of ticks are the most explanatory factors, while in Martinique, despite the fact that ticks are present, whatever their profusion and the cattle breed, dermatophilosis has a higher Incidence. Thus, disease prevention must begin with the most elimination possible of the ticks or/and the rearing of resistant cattle. Other elements such as age, body condition and physiological situation of females are influencing the probability for infection.