What Is Onchocerciasis?
Onchocerciasis, also commonly known as river blindness, is a Neglected Tropical Disease (NTD) which, in its extreme form, can lead to visual impairment and irreversible blindness — onchocerciasis is the second leading cause of preventable blindness due to infection.
What Causes Onchocerciasis?
River blindness is contracted from a parasitic worm called Onchocerca volvulus, transmitted by black flies (Simualiam spp.) that live near fast-flowing rivers and streams. Once people are bitten by the infected black fly, they experience skin depigmentation and severe itching.
The disease is endemic in 37 countries worldwide, and more than 99% of infected people live in 30 African countries. Currently, around 218 million people live in endemic areas (WHO report 2019-2020). Eliminating the transmission of river blindness worldwide could save the sight of thousands of people each year.
History Of Onchocerciasis
Though onchocerciasis has been in existence for centuries, it was first scientifically observed about 140 years ago. It is thought to have originated in the major river basins of Africa and spread outside the continent via human activity.
Prevention and Treatment Of Onchocerciasis
River blindness can be treated and prevented through repeated mass drug administration (MDA) for a period of 10-15 years, which is the lifespan of the adult worm. The primary drug for treatment of river blindness is Mectizan (ivermectin), donated by Merck & Co. free of charge for as long as necessary, and in areas where onchocerciasis and lymphatic filariasis are co-endemic, the treatment is ivermectin co-administered with albendazole, which is donated by GSK.
The MDA treatment kills the parasite larvae (microfilariae) in the human body, preventing blindness and skin disease in infected persons, and stopping the transmission of the parasite to others. In some countries, black fly vector control is also used as a complementary approach.
Elimination Of Onchocerciasis
Since 2012, four countries have eliminated river blindness. The global target set by the WHO is to eliminate onchocerciasis as a public health problem by 2030.