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The specificity of skin snips for onchocerciasis diagnoses is considered to be almost 100%. Our molecular methods revealed that microfilariae emerging from skin snips collected from highly microfilaremic Loa loa– infected individuals were largely misidentified as Onchocerca volvulus. This has important implications for onchocerciasis diagnostic testing in Loa -endemic areas. [ABSTRACT FROM AUTHOR]

Arecently developed polymerasechain reaction (PCR)-based assay is significantly more sensitive than current methods for diagnosing Onchocerca volvulus infection, and it overcomes many difficulties in identifying active onchocerciasis. Since chemotherapy is widely used to treat onchocerciasis, the utility of PCR in assessing responses to treatment and in predicting recrudescenceis important. Twenty-eight patients who had skin snips positive for microfilariae (Mf) were studied 120 days after receiving amocarzine, when each was negative for Mf: 16 (57%) were positive for O. volvulus DNA in the PeR-based assay. Of these, 14 (88%) were Mf positive when reassessed parasitologically on day 240, and all were Mf positive on day 365. Equally important was the finding that 12 patients had cleared both Mf and Mf DNA; only 1 was Mf positive at day 240. This suggests that the PeR-based assay provides a sensitive means for assessing infection status after macrofilaricidal chemotherapy and is an early predictor of persons likely to have a recurrence of Mf. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]