Is There Blinding Onchocerciasis in Northern Uganda?

Background: Onchocerciasis is a filarial nematode Onchocerca volvulus transmitted by female black flies which breeds in fast flowing rivers. Clinical manifestations is ocular or skin lesions. The long-term armed conflict in northern Uganda deprived research on onchocerciasis and no attempts have been made to establish the clinical manifestation of the disease in the region. Objective: To establish whether Simulium damnosum transmitted onchocerciasis in this region was blinding. Participants: Persons from thirteen endemic parishes in Pader district in northern Uganda were examined for clinical, parasitological and ocular manifestations of onchocerciasis. Results: A total of 675 persons were examined and microfilaria prevalence in skin snips was 28%, while nodules and onchodermatitis were 30% and 29% respectively. The commonest skin lesion was Chronic Papular Onchodermatitis (17.5%). However, the prevalence of both microfilaria in the anterior chamber of the eye and reversible ocular lesions was 4%. The reversible ocular lesions of onchocerciasis observed were punctate keratitis stage B (0.1%), punctate keratitis stage D (0.1%) and punctate keratitis stage E (3.7%). While 16.1% of the respondents had irreversible ocular lesions attributed mainly to Optic atrophy (6.4%) and sclerosing keratitis (5.2%). There was significant association between irreversible onchocerciasis lesions and visual loss (p< 0.0001). Conclusion: This study confirmed the occurrence of blinding onchocerciasis in Pader district, the first ever reported in indigenous populations in Uganda.