ONCHOCERCIASIS #WorldNTDday2024

Onchocerciasis – or “river blindness” – is a parasitic disease caused by the filarial worm Onchocerca volvulus transmitted by repeated bites of infected blackflies (Simulium spp.). These blackflies breed in the vicinity of remote villages on fertile region where people depend on agriculture, along swift-moving rivers and streams.

Onchocerciasis has an estimated infection rate of about 37 million people in tropical Africa and in isolated foci in Yemen and Latin America. The disease has been linked to more than 5 million cases of debilitating skin and eye diseases as well as 1.2 million cases of visual impairment or blindness. It is estimated that over 85 million people are living in endemic areas, with 99% of the cases resulting from Africa and half of this population residing in Nigeria.

In Nigeria, an estimate of about 17 million people are at risk of the disease, while 7-10 million people are infected. Consequently, Nigeria has been estimated to account for nearly 40% of the world’s prevalence of onchocerciasis.

Symptoms do not appear until after the L3 larvae mature into adult worm. Symtoms typically start to appear between 9 months and 2 years after initial acquisition of the parasite. These symptoms may include skin rashes, Extreme itching, Change of the skin pigmentation, Loss of skin elasticity which can make skin appear thin and brittle (leopard skin), Bumps under the skin called onchoceroma, Itching of the eyes, Cataracts, Light sensitivity, Loss of vision with swollen lymph nodes in rare cases, Enlarged groin.

There is currently no vaccine to prevent onchocerciasis. For most people, the risk of contracting onchocerciasis is low. Those most at-risk are residents of certain regions of Africa and Latin America. The best prevention is avoiding being bitten by blackflies. Wear long sleeves and pants during the day, and use insect repellant and wear permethrin-treated clothing. See a doctor if you suspect an infection so you can begin treatment before symptoms become severe.

World Health Organisation (WHO) recommends using Ivermectin and Moxidectin as preferred medications for treating Ochocerciasis due to its microfilaricidal property. Ivermectin is administered at least once yearly for dosing interval of 3-12 month, for a period of 10-12 years.