PREVALENCE OF AGGLUTINATING ANTI-LEISHMANIA ANTIBODIES IN 2 MULTI-THOUSAND BENGOLI COMMUNITIES

Control of endemic visceral leishmaniasis (VL) in large communities re quires a feasible epidemiological indicator capable of monitoring on-g oing transmission rather than mere exposure to the parasite. Following confirmation of the desired level of reliability for laboratory diagn osis of VL, the direct agglutination test (DAT) was employed to estima te VL sero-prevalence in the endemic upazilas (subdistricts) of Trisha l and Shahjadpur within Mymensingh and Sirajganj districts of Banglade sh. DAT antigen production was duly increased to allow coverage of a s tudy population of 17826 inhabitants, 9619 of whom resided in Trishal, 7328 in Shahjadpur and 879 in Teknaf (Cox's Bazar), a known Leishmani a-free district in Bangladesh. Despite large-scale production in batch es of 1120-4000 ml (each sufficient for 1176-6400 screening doses), al l DAT antigen batches performed as required in quality control tests f or sensitivity, specificity and stability. It was convenient for both collection and testing to take the required samples of whole blood by finger prick. A cross-sectional survey revealed VL point prevalences o f 4.40% in Trishal and 6.75% in Shahjadpur, compared with an extremely low rate of 0.34% in non-endemic Teknaf. In both endemic upazilas (Tr ishal and Shahjadpur) VL was more prevalent (2.56-4.5%) in persons up to 20 years of age than in those 21 years of age and older (1.84-2.25% ). Of 918 subjects recorded as seropositives, 539 were VL-asymptomatic and 379 were VL-symptomatic with various degrees of suspicion. Diagno sis of VL was established in 125 symptomatic seropositives subjects, e ither by demonstrating the presence of Leishmania amastigotes (29), or by positivie DAT results combined with presentation of typical VL sig ns (96). All diagnosed patients responded favourably to sodium antimon y gluconate administration; re-testing and follow-up procedures were s tarted on the remaining 793 seropositives. The DAT can be considered a s an appropriate and feasible alternative to the leishmanin and aldehy de tests for VL survey in large endemic communities.