Cytotaxonomic analysis of Simulium damnosum s.1. larvae collected from 23 sites across 4 bioclimatic zones in Nigeria revealed the presence of 5 cytospecies (S. damnosum s.str., S. sirbanum, S. squamosum, S. yahense and S. soubrense (including the Beffa form). The biogeographical distribution of the sibling species was mostly similar to that observed further west in the OCP area, although geographic cytotaxonomic variation was recorded in S. squamosum, S. damnosum s.str. and S. sirbanum. Some aspects of the chemical and physical environment of the breeding habitats were investigated.

Cytotaxonomic identifications of the Simulium damnosum complex (Diptera: Simuliidae) from Nigeria

A survey of the prevalence and socio-economic effects of onchocerciasis in Okpuje, Owan West L.G.A. of Edo State, Nigeria, was undertaken. Of the 655 persons enumerated in the community, a total of 200 subjects (102 males and 98 females) were randomly chosen for the study. The people were skin - snipped after undergoing a physical examination by a physician. The overall prevalence of infection was 47.5%. The symptomatic manifestations of the disease were: Leopard skin recorded the highest prevalence of 40.5%, ocular lesion, 14%; nodules, 10.5% and lizard skin, 7.5%. More males (27.5%) than females (20%) had onchocerciasis but the difference was not statistically significant (P > 0.05). However, age had a significant effect on the prevalence of onchocarciasis (P < 0.001). Socio- economic studies using structured questionnaires and interviews were carried out. The results indicated that onchocerciasis was associated with a variety of adverse social and economic effects on the people. 40.5% of subjects, mainly farmers and artisans, that presented with pruritus or itching complained of insomnia, general fatigue and lack of concentration at work, with a net effect of low productivity. Some children of infected parents reportedly dropped out of school. 14% of females with ocular lesions had given up jobs such as sewing, weaving and hair plaiting because of visual impairment thus leading to loss of personal and household economic productivity. 93.3% of subjects with lizard skin and 50.5% of those with leopard skin presented with varying levels of body disfigurement, had high level of low self-esteem, marital problems and social stigma.

Prevalence and socio-economic effects of onchocerciasis in Okpuje, Owan West Local Government Area, Edo State, Nigeria.

An epidemiological study on human onchocerciasis was conducted among 450 randomly selected farmers comprising of 213 males and 187 females within the age range of 20 - 50 years and above resident in Ebonyi central senatorial zone of Ebonyi State, Nigeria from January 2009 through December. Onchocerciasis infection was diagnosed by parasitological observation for the presence of microfilariae of Onchocerca volvulus in skin biopsies and adult filariae in excised nodules. Physical examination on the skin of each subject was carried out for Onchocercal depigmentation (Leopard skin) and visible nodules while ocular examination was carried out with illiterate E chat, ophthalmoscope and tonometer. One hundred and fifty (33.3%) farmers were infected with O. volvulus comprising 100(38.0%) males and 50(26.7%) females. The highest infection rate of 37(55.3%) was observed in subjects aged of 50 years and above while the least infection was within the age range of 20 - 29 of age 17(15.5%). 19(19%) of infected males and 3(6%) females had skin lesions due to onchocerciasis, partial blindness was observed in 6(6%) males and 3(9%) females, 64(64%) males and 20(40%) females had low vision while complete blindness was observed in 4(4%) males and 2(4%) females. The importance of implementing onchocerciasis control programmes such as African programme for onchocerciasis control (APOC) and onchocerciasis control programme in West Africa (OCP) in the study areas is hereby advocated.

	Key words: Onchocerciasis, microfilaria, leopard skin, nodules, Ebonyi State, Nigeria.

https://www.academicjournals.org/article/article1379179380_Okonkwo et al.pdf

Epidemiology of human onchocerciasis among farmers in Ebonyi State, Nigeria

Background: Onchocerciasis is endemic in the Imo River Basin, Nigeria. This study was aimed at assess­ing the prevalence and intensity of microfilaria of Onchocerca volvulus in the area. Methods: A cross-sectional study was carried out in the Okigwe Local Government Area, Imo State, Nige­ria. Two skin snips (one from the waist and another from the shoulder) were taken from 1024 individu­als examined. The survey coverage was high (91.8% of the study population). An individual was considered mf positive if either of the waist or shoulder snips or both were mf positive. The SPSS for Win­dows package was used for entering and analysis of data. Results: Thirty-seven percentage of those examined was positive for Onchocerca volvulus microfilariae (39.2% of males and 34.9% of females). The mf prevalence increased steadily with increasing age to reach 70.4% in the oldest age group. The overall mf Geometric Mean Intensity among mf positive individuals was 16 mf/skin snip and was significantly higher among males (18 mf/skin snip) than females (14 mf/skin snip) (p < 0.01). A scatter plot of microfilariae numbers in snips from the waist against numbers in snips from the shoulder of the same individuals, showed close correlation (Pearson's correlation coefficient = +0.90; p < 0.01), and those with mf intensities below 10 mf/snip had a more scattering tendency away from the regression line than those with higher mf intensities. Conclusion: Onchocerciasis is a public health concern in the area. Perhaps, 10 mf/snip is critical intensity threshold for reliable sampling using corneo-scleral punch.

/pdf/onchocerciasis-in-the-upper-imo-river-basin-nigeria-1gk7foozov.pdf

Onchocerciasis in the upper imo river basin, Nigeria: prevalence and comparative study of waist and shoulder snips from mesoendemic communities.

Onchocerciasis in pre-primary school children in Nigeria: lessons for onchocerciasis country control programme.

The prevalence of onchocercosis was determined in three Local Government Areas (Ezeagu, Oji-River and Uzo-Uwani) in Enugu State, Eastern Nigeria between March 1989 and June 1990. Enugu State was shown to be mesoendemic for onchocercosis. A total of 7472 (26.9%) persons out of 27,831 examined were positive for skin microfilariae. There was no significant difference in infection rates between males (27.6%) and females (26.2%). Of the 118 villages surveyed only five had no inhabitant with skin microfilariae. There was a progressive increase of prevalence to the second decade of life, although 96.6% of cases with skin microfilariae had only a light infection. Onchocercomata prevalence was recorded as 27.3% which tallies with the prevalence of skin microfilariae at 26.9% hence onchocercomata prevalence may be used as a yardstick for predicting skin microfilariae prevalence.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022149X00013699

L.N. Nweke

Papers

Results of a large scale onchocercosis survey in Enugu State, Nigeria.