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

Acta Trop. 1992 Jun;51(2):143-9. doi: 10.1016/0001-706x(92)90056-4.


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.

PIP: In 1989-90, health workers surveyed 2876 persons from 14 communities in the northern part of the Taraba River valley in the northeastern Taraba State of Nigeria to determine the prevalence and magnitude of eye involvement in respect to the rate and intensity of Onchocerca volvulus, the etiologic agent of onchocerciasis. 11.8% of the population were blind. Only 1 village did not have anyone who was blind (Mayoselbe). The village of Bobi had the highest blindness rate (71.9%). 20% of the population in all 6 hyperendemic communities were blind. 16.%% of all people suffered from impaired vision, the rates for which varied from 0.6 in Mayoselbe and 42.1% in Gangumi. 8.7% of the population suffered from sclerosis and 6.9% from opacity. All types of visual involvement of 0. Volvulus increased with age. Only 21.8% of =or 50 year old males and 25.2% of same age females had normal vision compared with 90.2% and 97.7% of =or 9 year olds, respectively. Sclerosis and impaired vision were most common in adolescents and blindness and opacity were most common in adults =or 30 years old. Overall there were no differences in eye involvement between males and females. Microfilarial load was significantly related to level of vision and presence of eye lesion (p.01). Blindness and opacity were more prevalent in people with 100 microfilariae/skin snip (MF/SS). Impaired vision and scerlosis tended to occur in people with 50 MF/SS. These results confirmed that the Taraba River valley is the country's worst foci of onchocerciasis and perhaps even the worst in West Africa. They indicated the need for mass distribution in ivermectin soon to prevent land depletion and increase income from optimum use of the fertile land.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Animals
  • Blindness / epidemiology*
  • Blindness / parasitology
  • Child
  • Child, Preschool
  • Corneal Diseases / epidemiology*
  • Corneal Diseases / parasitology
  • Female
  • Humans
  • Infant
  • Male
  • Microfilariae / isolation & purification
  • Middle Aged
  • Nigeria / epidemiology
  • Onchocerca / isolation & purification
  • Onchocerciasis, Ocular / epidemiology*
  • Onchocerciasis, Ocular / parasitology
  • Prevalence
  • Skin Diseases, Parasitic / epidemiology
  • Skin Diseases, Parasitic / parasitology
  • Vision Disorders / epidemiology*
  • Vision Disorders / parasitology
  • Visual Acuity