Field Diagnosis of Onchocerciasis in an Area of High versus Low Endemicity: Evaluation of the Dot Blot Assay

Abstract

Parasitological examination of skin snips is the most widely used diagnostic method for onchocerciasis, but it is associated with inconvenience and low sensitivity. We describe an inexpensive antibody-based dot blot assay (DBA) for the detection of Onchocerca volvulus infection. A field evaluation of this method was performed in the onchocerciasis endemic country Ghana by testing 370 individuals living in a highly onchocerciasis endemic area and 122 in an area of low endemicity. Sera from individuals with other filarial infections were also tested. The DBA was able to detect 95% of the parasitologically confirmed infected individuals in the highly endemic area. Cross-reactivity occurred with a minority of the sera from individuals infected with other filarial worms. The DBA was as good as or superior to presently available diagnostic tests, and it also fulfilled the criteria for a good screening method.