Why Isn't Onchocerciasis A Big Blindness Issue In These Two Sierra Leone Villages?

In Sierra Leone, onchocerciasis is a big worry in 14 out of its 16 districts. But two villages in Tonkolili district, Mangobo and Petifu, haven't seen much blindness from this disease. This raised eyebrows because, since 2005, these villages have had 17 rounds of annual treatments with ivermectin, a drug that fights this worm infection. A curious thing happened though. A local politician reported a rise in vision problems thought to be linked to onchocerciasis in these villages. The Sierra Leone National Neglected Tropical Disease Program wanted to get to the bottom of this. They conducted a serious investigation, checking eyes, blood, and symptoms of adults and kids aged 5 to 9 to understand the connection between vision loss and onchocerciasis. Even after 17 years of treatment, onchocerciasis didn't seem to be the main cause of vision issues in the adults tested. In fact, kids' blood tests showed a surprising low exposure to the worm. This was a puzzle because the villages have been undergoing treatments for so long. But sometimes, drugs aren't enough; other factors like access to clean water, sanitation, and better healthcare might play a role too. Health professionals always thought that onchocerciasis was a key reason for blindness in Sierra Leone. But it's not the whole story. Maybe we need to look at the bigger picture – including better healthcare, clean water, and nutrition – to solve health issues.