Bovine dermatophilosis (Derma­tophilus congolensis) in the French West Indies. III. A comparison between infected and uninfected cattle

Abstract

The determination of the distinctive features between infected and uninfected cattle by Dermatophilus has been performed among 93 bovine stock in La Martinique, and 120 in La Guadeloupe and Saint­ Martin Islands. Nearly half of the herds had been or were infected. Morbidity rates reach 33 per cent in La Martinique and 29 per cent in La Guadeloupe with a mortality ratio of 15 per cent and 5 per cent respectively. No frequency difference could  be observed  with respect to the season or the geographical area. Similarly, differences are little or nil as regards animal exposure toward agressive factors such as sun, soil moisture, thorns, etc. On the other hand, the presence of Amblyomma variegatum is a determining factor considering the prevailing situation in La Martinique, where ail breeds of cattle are sensitive to the disease. In this case, 63 per cent of the tick infested cattle develops dermatophilosis versus 2.5 per cent for the still uninfected animais. Conversely, in La Guadeloupe were Creole zebus are highly resistant (as a consequence of their natural selection), only 27 per cent of the infected stock suffers from this illness. In these two islands, regular dlpping measures have proved  to be  beneficial in that it reduces the disease frequency. The study also reveals an underlying typology of the various rearing systems, thus allowing their classifica­ tion as for their behaviour and response when meeting illness. In La Martinique, whatever they may be, quite none of them is infected in  the tick free area. In the tick infested zones, the traditional small breeders rearing a sensitive cattle and who do not care with prophylactic rules, are mostly stricken, while more structured ones have succeeded in controlling the disease, owning to some appropriate measures together with a fair animal management. On the other band, in La Guadeloupe where this tick is cosmopolitan, the small breeders who run a resistant Creole cattle, are not concerned, despite a rudimentary prophylactic behaviour. Conversely, the intensive rearing system, based upon improved imported breeds, meets great difficulties to master the infection.