Bovine hypodermosis in north-eastern Algeria: prevalence and intensity of infestation.

Between 1989 and 1997 different factors related to warble fly infestation ( prevalence, intensity, climate, breed) were studied in north-eastern Algeri a. Mean prevalence during the period was 76 %. This figure was obtained fro m a cattle market survey of four different regions (Jijel, Constantine, Gue lma, and El Tarf). One-hundred percent of the herds were found to be infest ed in El Tarf and 61 % of animals were infested. Within a herd, the intensi ty of infestation decreased with the age of the cattle. The mean number of warbles per animal decreased as reinfestations occurred. The peak of the em ergence of warbles observed between January and March was progressively del ayed in the older animals. Two species of Hypoderma were present in cattle in Algeria (H. bovis and H. lineatum) with a predominance of H. lineatum (6 3 %) in the semi-arid area (Batna) and a majority of H. bovis (75 %) in hum id area (Jijel). Warbles appeared earlier in Batna (October) than in Jijel (November). The Prim'Holstein breed was more susceptible to the warble fly infestation than Montbeliard or local breeds. The implementation of a contr ol programme for hypodermosis in Algeria is urgent. Control can be achieved through a mass treatment of cattle. This approach must take into account t he factors described in this study which influence the epidemiology of the disease. (C) Inra/Elsevier, Paris.