Onchocerciasis

Onchocerciasis presents differently in travelers compared with long-term residents of endemic areas and should be considered a diagnosis whenever travelers present with pruritus, unilateral limb swelling, or itchy skin lesions, with or without eosinophilia. Furthermore, travelers may present many months after leaving an endemic area, so a good travel history is essential. The infection is endemic across tropical Africa and in foci in Brazil, Venezuela, and Yemen. It is caused by a nematode parasite called Onchocerca volvulus which is transmitted to humans by bites of Simulium blackflies that breed near rivers. Prevention is by strict methods to reduce the risk of insect bites.