ABSTRACT
During the APOC/WHO Impact Assessment studies in Nigeria held in 1998 and 1999, one thousand and sixty four randomly selected subjects underwent detailed eye examination in three selected sites namely, Cross River State (rain forest ecological zone), Taraba State (savanna ecological zone) and Kogi State (forest- savanna ecological zone). The general objective of the impact assessment studies was to evaluate the ophthalmological impact of onchocerciasis control (CDTI) in Nigeria, this paper highlights the public health significance of ocular onchocerciasis in three different ecological zones in Nigeria. The presence of ocular onchocerciasis was established in all the study sites, with a predominance of posterior segment manifestations, in the rain forest zone. A blindness prevalenc e of 2.4o/o was recorded in the study, with onchocerciasis being responsible for 13 out of the 43 (30.2%) bilaterally blind subjects identified. Onchocerciasis-induced blindness prevalence was relatively high in the rain forest and forest savanna zones of Cross River and Kogi States with Cross River State having the highest site-specific- prevalence (5/10) 50.0% of onchocercal blindness followed by Kogr with (5/12) 41.7%. Taraba site recorded only 27.3% (3121). Other conditions identified included glaucoma, optic nerve disease and cataract rates of which were also found to be high among the population (6.90/o,6.5 % and8.9oh respectively). Anterior segment onchocercal lesions, punctate and sclerosing keratitis were the predominant features of the infection in Taraba site (14.1o/o and 6.3% respectively), a savanna zone while posterior segment lesions were much more common in the forest zone of Cross-River site. Visual field measurements reflected the predominant posterior segment disease. The need to sustain the present efforts aimed at controlling onchocerciasis through mass ivermectin distribution is fuither highlighted. Integration of other Eye Care Programme for the conffol of glaucoma and cataract, into the community directed treatment initiative of APOC for onchocerciasis control should also be strongly considered, in order to drastically reduce the prevalence and incidence of ocular morbidity and blindness, in Nigeria, especially in the onchocerciasis endemic areas.
Subject(s)
Onchocerciasis , Therapeutics , IvermectinABSTRACT
A cross-sectional survey of eye disease supported by the African Programme for Onchocerciasis Conffol (APOC) was carried out in October 1998, in Raja, Sudan, a Savanna ecological zone to determine the prevalence and distribution of onchocercal eye disease. Detailed eye examination including measurement of visual field using the Wu-Jones computerized Motion Sensitivity Screening Test (MSST) were carried out. A total of 481 individuals were examined, of which 379 underwent detailed eye examination. A high prevalence of blindness (8.1%) from all causes was recorded. Onchocerciasis-induced eye disease was responsible for blindness in 56.40/o of all blind persons. Of the 38 persons who had visual impairment, 13 (2.7%) were severely affected. As many as 91 (24.0%) persons had microfilariae (mfs) in the anterior chamber (AC) and /or cornea with the highest prevalence of 29.3Yo and 28.8% respectively, recorded among the young and active individuals. This age group (15-24yeus) also had the highest prevalence (15.3%) of flufff corneal opacities. Sclerosing keratitis was present in 46 (12.1%) subjects while iridocyclitis was diagnosed in 9.0% with the highest prevalenc e of 25 .0o/o noted in the 45 - 54 age group. Prevalence of blinding cataract was 54.1% while that of glaucoma was12.2%. Presumed optic nerye disease, a known pathway to onchocercal blindness was observed in 19.6% with one third of this percentage already at the advanced stage. Another common pathway to blindness, chorioretinitis, affected 15.2% of the subjects of which 7.2% had reached advanced stages.Prevalence of abnormal visual fields was 6.6Yo. Posterior segment oncho disease was found to be the main ocular pathology in 15.6% subjects followed closely by 13.5% whose main cause was anterior segment oncho lesion. Both sexes were almost equally affected. Ocular findings in this area particularly among the young conform to high intensity levels of onchocerciasis infection and therefore require urgent effective intervention to forestall further devastating oncho-induced blindness and alleviate the socio-economic burden imposed on this population.