Onchocerciasis and its Socioeconomic Effects in some Parts of IMO State, Nigeria

Human infection with Onchocerca volvulus and its socioeconomic conséquences were investigated in parts of the Imo River Basin of Nigeria between March 1996 and December 2000 using standard parasitological and socioeconomic methods. The Knowledge, attitude and perception of the inhabitants to the disease and its treatment with ivermectin as weil as the microbial agents associated with onchocercal skin lésions were also determined. Of the 7,348 persons randomly examined by the skin snip method, 1,655(22.5%) were infected with microfilariae of 0. volvulus. The prevalence of infection differed (P<0.05) between communities in the upper Imo River Basin (26.8%) and the middle Imo River Basin (19.0%). A mean microfilarial density, 20.1mf/ss was obtained. There was no significant différence (P>0.05) in sexrelated infection. 22.9% in maies and 22.1% in females. Classical symptoms of the disease were observed in varying rates. Less than half of the viliagers (48.2%) used to assess community Knowledge knew about the disease and only about 5% attributed transmission of infection to the vector fly, Simulium damnosum. Persons afflicted with visible manifestations like dermatitis, lymphoedema (limb) and blindness were notconsidered good for marriages or hired as farm hands. The percentage drop in school attendance of pupils was higher in househoids where family heads had severe onchocercal skin disease (OSD) (4.9%) than in househoids with family heads of non-OSD status (2.1%). The total revenue loss due to direct costs of treatment and man-days lost to incapacitation was remotely estimated at HQ2 million annualiy. 79.8% persons accepted ivermectin, while 68.8% complied with yearly treatment. This was attributed to severai factors Including effective grassroots mobilization, community participation in the planning and implementation of the programme and perceived efficacy of the drug. Microorganisms isolated from excoriated onchocercal skin lésions included Staphylococcus aureus (89.9%), Streptococcus pyogenes (50.8%), Pseudomonas aeruginosa (21.8%),
Escherichia coli (60.7%), Bacteroides spp (11.5%) and Clostridium spp (3.3%). Majority of these organisms exhibited moderate to marked susceptibilities to broad spectrum antibiotics iike Tarivid, Ciproxin and its derivative, Norfloxacin. The results of the study have shown that despite the mesoendemic nature of onchocerciasis in the study area, it is still a serious problemconsidering the associated skin lésions, gross lymphatic pathologies and their négative impact on marriage, productivity and attendance to school. These findings underscore the need to sustain treatment with ivermectin and possibly on a semi-annual basis.