COMMUNITY DIAGNOSIS OF BANCROFTIAN FILARIASIS

The objective of this study was to find the best tests for efficiently estimating the true prevalence of Bancroftian filariasis in endemic a reas. The study population comprised 427 people over 10 years of age i n an endemic village in Egypt. Four tests were evaluated; a standardiz ed clinical examination, night blood examinations for microfilariae (5 0 muL thick films and 1 mL membrane filtration), and a test for circul ating filarial antigen. 191 subjects (44.75%) had at least one positiv e test and were considered to have filariasis. The sensitivities of cl inical examination, thick films, membrane filtration and antigen testi ng for filariasis were 16%, 50%, 64%, and 88%, respectively. Relative to membrane filtration of night blood, the filarial antigen test had a sensitivity of 97.5%, a positive predictive power of 71%, and a negat ive predictive power of 99%. None of the blood tests was a sensitive i ndicator of clinical filariasis; 69% of clinical cases were negative i n all 3 blood tests and would have been missed if clinical examination s had not been done. Therefore, we recommend a combination of clinical examination and the filarial antigen test (with optional examination for microfilariae of those with positive antigen tests) for community diagnosis of Bancroftian filariasis in endemic areas.