Characterisation of nuclear ribosomal DNA sequences from Onchocerca volvulus and Mansonella ozzardi (Nematoda : Filarioidea) and development of a PCR-based method for their detection in skin biopsies

The internal transcribed spacer region (ITS1, 5.8S gene and ITS2) of the tw o filarial nematodes Onchocerca volvulus and Mansonella ozzardi was sequenc ed, and two species-specific primers designed in the ITS2 to develop a PCR- based method for their specific detection and differentiation. When used wi th a universal reverse primer, the two species-specific primers gave amplif ication products of different size, which were readily separated in an agar ose gel. The PCR was tested on skin biopsies from 51 people from three loca lities in Brazil where M. ozzardi is present, and results have been compare d with those of parasitological examination of blood. The species-specific PCR gave a higher percentage of detection of infection by M. ozzardi than t he parasitological examination of blood. No infection with O. volvulus was detected by PCR. This PCR-based assay may assist in determining the nature of infection in areas where both filarial species exist in sympatry. (C) 20 01 Australian Society for Parasitology Inc. Published by Elsevier Science L td. All rights reserved.