Loiasis, or African eye worm, is caused by infection with the filarial parasite Loa loa. The parasite is transmitted by deerflies in the Chrysops genus, which breed in tropical rainforests in West and Central Africa. Although repeated infection can cause painful, itchy swellings, the disease only emerged as a major public health concern when it was reported that individuals with high intensity Loa loa infection can develop severe adverse effects (SAEs) to treatment with the antifilarial drug ivermectin. This is an important concern given that preventive chemotherapy with ivermectin is used to reduce the transmission of LF and onchocerciasis.

To identify co-endemic areas for onchocerciasis or LF and loiasis, where individuals may be at risk of SAEs if standard MDA regimens were followed, a rapid assessment procedure for loiasis (RAPLOA) was implemented throughout potentially suitable countries.

Browse the maps to see the results of this assessment by country or for the entire region.