Microscopical and serological diagnosis of wuchereria bancrofti

Venous blood from 292 patients attending a Filaria Clinic in Georgetown, Guyana, was assayed by ELISA for IgG and IgM antibodies and by Indirect Haemagglutination Antibody Assay (IHA) against filaria parasites. They were also assayed by microscopic methods before and after concentration procedures for microfilaraemia. Of the 41 blood samples microscopically positive for Wuchereria bancrofti microfilfariae, 87.8//(ELISA IgG), 65.9//(ELISA IgM) and 73.2//(IHA) occurred in samples with subdiagnostic serological threshold titres of<1:32 (IgG and IgM) and <1:128(IHA). But indicators of value based on the standards of the presence 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 system (92.7//) was slightly better than a centrifugation technique (90.2//), but more efficient than a thick smear preparation (75.6//) for the detection of microfilariae. The filtration system was vastly superior for yields of microfilariae. However, the Knott's concentration (sedimentation) was the most economical in terms of technical time and materials. Most microscopically confirmed filaria cases were in the 20 - 29-year 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 concentration of microfilariae from peripheral blood be maintained in all Caribbean countries. In known filaria endemic countries, it is recommended that the serological tool be used as an aid in diagnosis for patients with acute and chronic symptoms

Evaluation of methods for the laboratory diagnosis of malaria in Guyana

When 297 blood samples taken from patients attending a fever clinic in Georgetowm Public Hospital were examined microscopically, after thick and thin blood films had been stained with Giemsa, one hundred and forty-two (47.8 per cent ) were microscopically positive for malaria. After processing the patients' serum samples by the Indirect Fluourescent Antibody (IFA) technique, specific IgG and IgM antibodies were detected in 239 (81.3 per cent ) and 179 (60.1 per cent ), respectively, of the sera. Based on the microscopical findings, the IFAT gave positive and negative values of 54.4 per cent and 81.8 per cent (IgG), and 57.5 per cent and 67.8 per cent (IgM), suggesting that the IgM would be more useful than the IgG in the diagnosis of current malaria. An odds ratio analysis showed that the presence of symptoms, IgG or IgM antibodies, as well as visits to endemic regions, could be good indicators of current malaria. Age and occupation are not. The microscopical method will continue to be the gold standard - the best available criterion for the validation of our tests - for our diagnosis of acute malaria.

Significant changes in gastrointestinal tract parasitic infections in children of St. Kitts over the 9-year period 1982-1991

When 239 (1982) and 361 (1991) five-year and nine-year-old children in St. Kitts were assessed for the presence of parasitic infections, there were significant reductions in the prevalence of trichuriasis from 83 per cent to 58 per cent , of ascariasis from 24 per cent to 8.6 per cent and of giardiasis from 15 per cent to 9 per cent . Anthelminthic use, which appeared to be the most important responsible intervention tool, remained roughly at the same level at 59-51 per cent . However, the types of anthelminthics used changed over the period. Piperazine citrate, which was used by 66 per cent in 1982, only had 35 per cent usuage in 1991. Albendazole which was not used at all in 1982 was taken by 32 per cent of the children in 1991 and at the same time the use of laevo-tetramisole increased by 20 per cent from 14 per cent . Suggestions are made for an island-wide mass intervention programme to manage parasitic infections.