RISK-FACTORS FOR OPTIC-NERVE DISEASE IN COMMUNITIES MESOENDEMIC FOR SAVANNA ONCHOCERCIASIS, KADUNA STATE, NIGERIA

Ophthalmic examinations on 6831 individuals aged 5 years or more, livi ng in 34 guinea savannah communities mesoendemic for onchocerciasis, i n Kaduna State, Nigeria, revealed a relatively high prevalence (9%) of optic nerve disease (OND). Further investigations were performed to d etermine what proportion of this burden of OND might be due to onchoce rcal infection. Information on history of cerebro-spinal meningitis (C SM), past use of diethylcarbamazine (DEC) and chloroquine, consumption of cassava and locally produced alcohol was collected for all individ uals by questioning. In addition, a nested case-control study of 81 ca ses of OND and 136 age and sex-matched controls was performed to inves tigate whether syphilis or a variety of other neurological disorders w ere responsible for a substantial proportion of cases of OND. Our data suggest that in this population, onchocercal infection is the single most important cause of OND and may account for 50% of all cases. Some 13% of cases were associated with signs suggestive of glaucoma. DEC u se might be responsible for up to 30% of all OND. We found no evidence to suggest that any of the following are important causes of OND in t he communities studied: CSM, syphilis, neurological syndromes such as polyneuropathy or other generalized neurological disease, consumption of raw cassava, consumption of locally prepared alcohol.