PREPATENCY PERIOD AND SOME ASPECTS OF THE EPIZOOTIOLOGY OF ONCHOCERCA-OCHENGI INFESTATION IN CATTLE IN THE ADAMAWA PLATEAU, CAMEROON

In an onchocerciasis endemic area, calves which were one to 24 months old, were examined for palpable Onchocerca ochengi nodules and microfilariae in skin snips. A highly infested bait oxen was used for the production of infective larvae through the vector Simulium squamosum. A prepatent period of about 10 months for the appearance of palpoble nodules and skin microfilariae was identified, and the prevalence of nodules (80.5 %) and the microfilorial density (0.74 microfilariae per mg skin biopsy) was highest in the 19-24 months old animals. Peaks of 4.8 infective larvae per blood fed fly were reached during infective larvae production. The ease of counting palpable nodules, collecting blood and skin snips, performing nodulectomy, isolating adult worms, keeping these in vitro and producing infective larvae provides favorable conditions for the use of this animal model for in vivo chemotherapy and vaccine development research.