MICROSCOPIC AND SEROLOGICAL DIAGNOSIS OF WUCHERERIA-BANCROFTI

Venous blood from 292 patients attending a Filaria Clinic in Georgetow n, Guyana, was assayed by ELISA for IgG and IgM antibodies and by Indi rect Haemagglutination Antibody Assay (IHA) against filaria parasites. They were also assayed by microscopic methods before and after concen tration procedures for microfilaraemia. Of the 41 blood samples micros copically positive for Wuchereria bancrofti microfilariae, 87.8% (ELIS A IgG), 65.9% (ELISA IgM) and 73.2% (IHA) occurred in samples with sub -diagnostic serological threshold titres of < 1:32 (IgG and IgM) and < 1:128 (IHA). But indicators of value based on the standards of the pr esence of chronic and acute symptoms, the IgG and IgM diagnostic data gave 79.9% sensitivity, 96.4% specificity, 97.1% positive predictable value and 44.3% negative predictive value. A membrane filtration syste m (92.7%) was slightly better than a centrifugation technique (90.2%), but more efficient than a thick smear preparation (75.6%) for the det ection of microfilariae. The filtration system was vastly superior for yields of microfilariae. However, the Knott's concentration (sediment ation) was the most economical in terms of technician time and materia ls. Most microscopically confirmed filaria cases were in the 20 - 29-y ear age group (25%), followed by the broad 30 - 69-year age groups (10 - 12%). Males were significantly more commonly affected by the ratio 24.2:6.0. It is recommended that skills and materials for concentratio n of microfilariae from peripheral blood be maintained in all Caribbea n countries. In known filaria endemic countries, it is recommended tha t the serological tool be used as an aid in diagnosis for patients wit h acute and chronic symptoms.