STRAIN DIFFERENTIATION OF ONCHOCERCA-VOLVULUS FROM UGANDA USING DNA PROBES

Polymerase chain reaction (PCR) combined with non-radioactive DNA hybr idization was applied for the detection and characterization of a 150 bp tandem repeat of Onchocerca volvulus. DNA of worms from western Uga nda was amplified and then probed with a digoxygenin-labelled oligonuc leotide, specific for the forest form of O. volvulus and compared to s amples from various African countries. Hybridization was only observed with PCR products from the forest in Liberia, south-eastern Ghana, Be nin and southern Cameroon, but not with worms from Uganda or the savan nah in Burkina Faso and northern Ghana. A nested PCR using primers der ived form the forest form-specific DNA sequence confirmed these result s. Morphometric studies revealed length differences between the microf ilariae of Ugandan O. volvulus to those of West Africa, especially to those of the savannah in Burkina Faso. It is concluded that the forest /savannah classification of O. volvulus from West Africa is not suitab le for Simulium neavei-transmitted O. volvulus from Uganda.