Monarch Disease Ontology entry MONDO_0017137 (onchocerciasis) is a form of filariasis, caused by the parasitic worm Onchocerca volvulus, transmitted by the black fly. The infection can either be asymptomatic or manifest as an ocular disease (river blindness) with itchy eyes, erythema, photophobia, onchodermatitis or onchocercal skin disease (classified into acute papular, chronic papular, lichenified, atrophic, and depigmentated) and onchocercomas (over bony prominences). Other classic clinical manifestations are ichthyosis-like lesions (''lizard skin'') and ''hanging groin'', which may be associated with lymphadenopathy. Also known as: Onchocerca volvulus infection, infection by Onchocerca volvulus, volvulosis.