Every Monday and Tuesday morning, Bosede Oluwaokere, 48, wakes up at home in Ilorin city in west Nigeria, gets dressed and walks to a nearby stream. She sits beneath a tree and pulls her skirt up around her thighs. For the next six hours she stays in the same spot waiting for a specific type of fly to land on her, so she can catch it using a small plastic tube.
Oluwaokere is a human flycatcher – or human landing catch, as the World Health Organization (WHO) terms it – which is considered the “gold standard” for collecting black flies. Black flies, which breed near rivers, are blood-sucking insects that spread the debilitating neglected tropical disease onchocerciasis, also known as river blindness.
“I like this work,” says Oluwaokere, who was recruited as a volunteer by the health ministry. “I’m not scared to do it, because I love my community and I want it to be free from disease.” She is paid a stipend of 10,000 naira (just under £5) a month by Sightsavers, an international health charity.
In Nigeria, about 40 million people are at risk of onchocerciasis. There is no cure, but mass drug administration with Mectizan, donated by Merck, is used to prevent spread. After several rounds, tests determine whether elimination has been achieved, including testing 6,000 black flies in Nigeria.
There are ethical concerns. “It makes me quite uncomfortable as it’s a risky practice,” says Louise Hamill, director for onchocerciasis at Sightsavers. She notes risks of bites from other disease-carrying insects, snake bites, and exposure to sun and rain. Fellow volunteer Olamilekan Adekeye, a 26-year-old university student, once fled after seeing a black snake.
The WHO also recommends Esperanza window traps (EWT) as an alternative, but human flycatchers remain the gold standard for collecting black flies in Nigeria.
