Between 1989 and 1997 different factors related to warble fly infestation (prevalence, intensity, climate, breed) were studied in north-eastern Algeria. Mean prevalence during the period was 76 in a cattle market survey of 4 different regions (Jijel, Constantine, Guelma, and El Tarf). All of the herds were infested in El Tarf and 61 of animals were infested. Within a herd, the intensity of infestation decreased with the age of the cattle. The mean number of warbles per animal decreased as reinfestations occurred. The peak of the emergence of warbles observed between January and March was progressively delayed 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 (63) in the semi-arid area (Batna) and a majority of H. bovis (75) in humid 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 control programme for hypodermosis in Algeria is urgent. Control can be achieved through a mass treatment of cattle. This approach must take into account the factors described in this study which affect the epidemiology of the disease.
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