Dermal microfilariae recovered form specimens obtained from umbilical and cervical sites of cattle infected with adult Onchocerca gutturosa alone or with adults of O gutturosa and O lienalis were measured and compared with uterine microfilariae obtained directly from gravid female worms of each species. Uterine microfilariae of O gutturosa were longer than dermal microfilariae obtained from cattle harboring only adults of O gutturosa. Dermal microfilariae were recovered from umbilical and cervical sites in these cattle. Those found at the cervical site had lengths equal to or greater than lengths of microfilariae recovered from the umbilical site. There was a significant (P less than 0.0001) shift in length across populations of microfilariae of O gutturosa from various sites in its bovine host, with a progressive decrease in length between microfilariae recovered from the worm's uterus, microfilariae from the cervical dermis, and microfilariae from the umbilical dermis, respectively. A similar direct comparison was not possible for microfilariae of O lienalis, because none of the cattle was infected with only adult worms of this species. In an indirect comparison, microfilariae of O lienalis were identified at the umbilicus, but their presence in the cervical region could not be determined unequivocally because of confounding of microfilariae length by concurrent infection with O gutturosa. Uterine microfilariae from O lienalis were longer than uterine microfilariae of O gutterosa, although a degree of overlap in the range of measurements existed between species.

There is increasing alarm and awareness about the health dangerposed by the arthropod vector causing Onchocerciasis. This study was carried out with the aim to throw more light on the prevalence of the arthropod vector, Simulun damnosum. This research enabled us toproffer preventive advice to government and citizens. In carrying out this study, villages around flowing waters were used as sample sites. The method applied was direct observation, coupled with efficientrecording. Atmospheric temperature readings were periodically taken along with the density of the insect population observed under such temperature. The same was done for relative humidity (%), solar radiation (gm-ca/cm2, lum) and luminescence (cd/m2) in relation to the insect population of available FMH at every given period (fly per man hour). Our findings showed that climate conditions influence the reproductive level and numbers of the vector. The wet season is most conducive for the arthropod vector to reproduce and multiply. The humidity is high and temperature seems to be at the average. It is during this period that greater preventive measures need to beintentionally heightened to subdue the dangerous activities of the vector.