Black fly attractants and the control of Onchocerciasis

Onchocerciasis or river blindness disease is a parasitic disease caused by infection from the nematode Onchocerca volvulus. The parasite is transmitted to humans by black fly vectors of the genus Simulium. Most of the infections occur in central Africa, with significant incidence also in Central and South America. The World Health Organization (WHO) estimates 18 million people suffer from onchocerciasis. However, due to a prolonged period from infection to hosts becoming symptomatic it is difficult to accurately access infection. The current method for monitoring the spread employs human bait, which is neither optimal nor ethically sound. The need for a new monitoring method is very important. It was noticed that anthropophilic gravid flies are attracted to both egg masses recently deposited by other flies of the same species as well as human scent. This paper will describe our efforts to isolate and identify the compounds responsible for this attraction using a variety of analytic methods such as LC-QToF, GC-MS and EAG. The identified compounds will be developed as bait for a field trap for monitoring vector pressure in both Latin America and Africa. In the long term, field traps may be useful in eradication of the disease.