Polymerase Chain Reaction-Based Diagnosis of Onchocerca volvulus Infection: Improved Detection of Patients with Onchocerciasis

Abstract

Definitive diagnosis of Onchocerca volvulus (Ov) infection requires the identification of the parasite in either the skin or subcutaneous nodules. These parasitologic approaches suffer from poor sensitivity. To assess the efficacy and utility of a polymerase chain reaction (PCR)-based diagnosis for Ovinfection, skin snips were examined from 94 persons in an Ov-endemicregion of Ecuador, and results were compared in a blinded fashion with those of a PCR assay based on the Onchocerca-specific repetitive DNA sequence, 0-150. All 60 patients microfilaria-positive on skin snip examination were positive in the PCR-based assay. In addition, 13 of 34 who were microfilaria-negative by skin snips were positive in the PCR assay. This suggests that the PCR-based assay is significantlymore sensitive than current methods and overcomesmany deficiencies of parasitologic and serologic methodologies in diagnosing active onchocerciasis.