Eye lesions, blindness and visual impairment in the Taraba river valley, Nigeria and their relation to onchocercal microfilariae in skin

doi:10.1016/0001-706X(92)90056-4

Acta Tropica

Volume 51, Issue 2, June 1992, Pages 143-149

https://doi.org/10.1016/0001-706X(92)90056-4 Get rights and content

Abstract

2876 persons in fourteen communities in the Taraba River Valley, Nigeria were examined for eye lesions and tested for visual acuity using the ‘tumbling E’. The individuals were also examined for microfilaria of Onchocerca volvulus. More than one-tenth of the population were blind, while another 16.1% had visual impairment. The prevalence of blindness was in excess of 20% in six communities, with one community recording 71.9% blindness rate. All forms of visual involvement increased with age but were similar between sexes. Eye lesions were related to the level of vision. Both eye lesions and vision deteriorate with increase in age. Vision seems to worsen with increase in prevalence and intensity of O. volvulus. Large microfilarial loads were associated with severe eye damage and blindness. These findings indicate that the Taraba river valley could be one of West Africa's worst foci of onchocercal blindness.

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Onchocerciasis-associated epilepsy: an update and future perspectives
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Citation Excerpt :
Prior to the implementation of onchocerciasis control programmes, the prevalence of onchocerciasis-related blindness in onchocerciasis hyperendemic regions was very high. For example, in 1989–1990, more than 10% of the population was blind and 16.1% had vision impairment in certain villages in the Taraba River Valley, Nigeria [37]. In the presence of such an important public health problem caused by onchocerciasis-related blindness and in the absence of clinicians to diagnose seizure disorders in these remote areas, an epilepsy problem among children and adolescents may have gone unnoticed.
Onchocerciasis-associated epilepsy (OAE) is an important neglected public health problem in areas with high ongoing onchocerciasis transmission. The risk that children in such areas develop epilepsy is related to their Onchocerca volvulus microfilarial (mf) load. Before the implementation of mass treatment with ivermectin, microfilariae were detected in cerebrospinal fluid (CSF). More recently, neither O. volvulus microfilariae nor DNA were detected in CSF or brain tissue; however, these samples were obtained years after seizure onset. It is possible that during fever-induced increased blood–brain barrier permeability, microfilariae enter the brain and, upon dying, cause an inflammatory reaction inducing seizures. Including OAE in the onchocerciasis disease burden estimation may mobilise extra resources for onchocerciasis disease elimination and treatment/care of OAE-affected persons/families.
Onchocerciasis-Associated Epilepsy, an Additional Reason for Strengthening Onchocerciasis Elimination Programs
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Citation Excerpt :
In a 25 year follow-up study of 295 909 persons with onchocerciasis, it was shown that the relative risk of dying was significantly higher in O. volvulus-infected individuals <20 years old compared with those >20 years old [33]. This excess mortality cannot be explained by onchocerciasis-induced skin or ocular lesions (blindness because of onchocerciasis rarely occurs below the age of 20 [34]) but most likely is caused by the high mortality caused by OAE. Given the accumulating evidence that NS is only one of the clinical presentations of onchocerciasis, and that the majority of O. volvulus-infected individuals present with other forms of epilepsy [2], we propose to stop using the terms ‘NS' and ‘Nakalanga syndrome' but, instead, use the term OAE.
A high prevalence of epilepsy has been observed in onchocerciasis-endemic regions with high onchocerciasis transmission. Recent epidemiological studies suggest that Onchocerca volvulus infection is the trigger causing the seizures, which appear in previously healthy children between the ages of 3 and 18 years. Persons with onchocerciasis-associated epilepsy present with a wide spectrum of seizures, including atonic and myoclonic neck seizures; but also absences and most frequently generalized tonic-clonic seizures. Often individuals present with intellectual disabilities and psychiatric disorders and occasionally with ‘Nakalanga’ features such as severe stunting with delayed or absent external signs of sexual development. Onchocerciasis-associated epilepsy, because of its importance as a public health problem, is an additional reason for strengthening onchocerciasis elimination programs.
Onchocerciasis in pre-primary school children in Nigeria: Lessons for onchocerciasis country control programme
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There is limited data on the prevalence of onchocerciasis in young children in Nigeria, partly because treatment with the effective drug Ivermectin has been contra-indicated in children less than 5. As the risk of complications of onchocerciasis is related to duration and intensity of infection, it would be beneficial to know the prevalence in young children for design of control programmes. A study was therefore undertaken to determine the prevalence of onchocerciasis in 642 children 0–4 years old in a rain forest endemic community in South East Nigeria. The overall onchocerciasis prevalence (positive skin snips) for children 0–4 years old in three Local Government Areas in Enugu State, Eastern Nigeria was 15.7% with no significant difference in infection rates between male and female children. There was no detectable infection in children less than 1 year old. Characteristic onchocercal rash was identified in 11.1% of the children and presence of typical onchocercal subcutaneous palpable nodules in 4.6%. Total prevalence for adults in the same population was found to be 26.9%. This indicates that in onchocerciasis endemic communities, everybody may be at risk of infection irrespective of age.
Onchocerciasis in Taraba State, Nigeria: Clinical-epidemiological study of at-risk males in Bakundi district
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An epidemiological study of 1366 adult males from fourteen communities of Bakundi district of Taraba State, Nigeria was carried out to establish the prevalence and intensity of onchocerciasis.
The findings of the study showed that 45.2 % of subjects were infected. Ten communities had infection rates in excess of 30 %. Lizard skin and leopard skin were seen in 3.5 % and 2.0 %, respectively, and increased with increasing age. Hanging groin (2.6%) and scrotal enlargement (8.6%) were also observed. There was a good correlation between the infection rate on one hand and the presence of nodules (r = 0.85, P < 0.05), hanging groin (r = 0.56, P < O.OS)and scrotal enlargement (r = 0.62, P < 0.05) on the other. There was also a significant correlation between the intensity of infection on the one hand and lizard skin (r = 0.67, P < 0.05), leopard skin (r = 0.88, P < 0.05) and hanging groin (r = 0.82, P < 0.05) on the other. Those who worked in the fields (such as hunters, farmers and fishermen) had higher infection than others because of frequent contact with the vector. Extensive surveys of all suspected river valleys must be carried out to identify all those communities which will benefit from ivermectin treatment.
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Original research paperEye lesions, blindness and visual impairment in the Taraba river valley, Nigeria and their relation to onchocercal microfilariae in skin

Abstract

Trans. R. Soc. Trop. Med. Hyg.

Trans. R. Soc. Trop. Med. Hyg.

Hyperendemic onchocerciasis in The Taraba river valley of Gongola State (Old Adamawa Province) Nigeria

Ann. Parasitol. Hum. Comp.

Ocular onchocerciasis in a hyperendemic village in the rainforest of Liberia

Tropenmed. Parasitol.

The prognostic value of headnodules and microfilariae in the skin in relation to ocular onchocerciasis

Onchocerciasis, symptomatology, pathology, diagnosis

Original research paper
Eye lesions, blindness and visual impairment in the Taraba river valley, Nigeria and their relation to onchocercal microfilariae in skin