Studies on epidemiology and effects of human onchocerciasis on productivity and social lives of rural communities in uzo-uwani local governement area of Enugu State, Nigeria

Some aspects of the epidemiology of human onchocerciasis as well as the effects of the disease on the productivity and social lives of rural communities in Uzo-Uwani local government area of Enugu State were studied using the survey method. The prevalence of the disease among the 16 communities that make up the local government area based on the rates of nodule, leopard skin and impaired vision were investigated. The knowledge of the blackfly vector of the disease and its association with the manifestations of the disease in the population were also studied. The effects of the choice drug, ivermectin (Mectizan) on the nodule and the daily biting patterns of the vector (Simulium) for different seasons of the year were investigated. On the effects of onchocerciasis on the productivity of the inhabitants, two aspects were studied namely the effects on the productivity of farmers and on academic performance of school children. With regard to the effects of the disease on social lives, three aspects were studied namely the effects on social interactions between the infected and uninfected individuals, the effects
on the age at which infected persons marry and the effects on married life. The results of the studies. on the prevalence of onchocerciasis in UzoUwani local govermnent area showed that the whole area (100%) is endemic for the disease but the level of endemicity varied from community to community. One of the outstanding observations was that the northern part of the local government area closer to the savanna zone had higher prev·alence if based on rate of impaired vision (26.9%) rather than rate of nodules (16.9%). The southern part of the area closer to the forest zone however had higher prevalence rates if based on nodule rate (33.3%) rather than rate of impaired vision (18.9%). All communities in Uzo-Uwani local government area have the knowledge of the blackfly vector of onchocerciasis although the level of knowledge varied between communities; Generally, communities with higher prevalence of the disease have better knowledge of the vector. Unfortunately, none of the communities had any knowledge of any association between the bit~s of the blackfly (Simulium) and the observed manifestations of onchocerciasis. Rather they attributed these manifestations to old age or familial traits. On the effects of onchocerciasis on the productivity of farmers, it was found that impaired vision and blindness Were the major disabilities that hindered farmwork. Other disturbances resulted from the distractions attributable to Simulium bites which made the farmers lose some man-hours and this resulted in lower output. The study on the effects of different manifestations of onchocerciasis on academic performance of school children gave some interesting results. From regression analysis of different manifestations, namely impaired vision, rashes and palpable nodules, and academic performance, it was observed expectedly that impaired vision had the highest correlation with performance ( correlation coefficient, r = - 0. 72). The higher the rate of impaired vision, the poorer the performance. Rashes had a marginally significant correlation with performance (r = - 0.014) while the nodule rate had no negative effect on performance (r = 0.36). Results from respondents on social effects of onchocerciasis showed that there is social . discrimination against people suffering from onchocerciasis especially those with the presence of rashes. Other manifestations did not attract any social stigmatization. Young people, especially girls, with rashes marry later than those without such manifestations and they marry partners that they would not ordinarily have married such as old people, divorced people and people that did not have children from their previous marriages. The appearance of onchocerciasis manifestations did not, however, have any significant effect on already established marriages. On the study of the effects of the choice drug for onchocerciasis treatment (ivermectin) on the histology of the nodule, it was observed that the female worms whose uteri were normally filled with microfilariae were empty and there were no intact micro:filariae within the connective tissue of the nodules contrary to the observations in untreated onchocerciasis patients. On the daily biting patterns of the Simulium, it was observed that the peak biting periods displayed a ~imodal pattern. The pattern varied slightly with seasons. During the early rains, there was a low morning peak between 9.00 and 11.00 a.m .. and a higher evening peak between 4.00 and 6.00 p.m. Within the dry season, the harmattan period generally showed a low biting density up to 2.00 p.m. when more intense biting ensued with a peak occurring between 4.00 and 6.00 p.m. The greatest number of flies per man per day was recorded during the hannattan season. The possible implications of the findings in these studies are discussed and suitable control strategies against onchocerciasis based on the results recommended.