[Serodiagnosis of onchocerciasis using micro-ELISA. Study of 450 sera and comparison with indirect...

The microtest ELISA has been used for human Onchocerciasis serological study. The antigens employed were adult Onchocerca volvulus extracts, collected from dissected nodules, delipidized and cleared from human proteins by affinity Chromatography. Under the circumstances, the positivity limit of the test seems excellent (maximum )D: 0,23) defined with 171 negative sera, 66 of them taken from Africans. Specificity controls were studied with 56 heterologous sera; cross-reactions occurred with hydatidosis and especially wit various nematode infections, in particular loasis. With reagents and technical conditions used, the specificity limit of the test corresponds to an OD of 0,4 (measured with a 3 mm optical course). The diagnosis value of the test was verified by studying sera from 90 individuals wit a positive skin biopsy and with sera from 233 adults living in endemic areas. For all the infected people, the global percentage of positivity with ELISA is not greater than that with indirect immunofluorescent antibody test (85%). On the other hand, the micro-test ELISA seems slightly more sensitive in detection of high serological positivities. We did not find any statistically relationship presence and quantity of microfilarial worms in skin biopsy and positivity with the microtest ELISA. Likewise, in some polyinfested patients (with Onchocerca volvulus and Dipetalonema perstans or Wuchereria bancrofti), we did not observe any correlation between the results given the microtest ELISA and the quantity of microfilariae in the blood stream.