A comparative study of detection methods for evaluation of microfilaremia in lymphatic filariasis control programmes.

The evaluation of microfilaremia (mf) was performed in 96% of the population aged 15 years or more in a village of Moorea, one of the Society Islands in French Polynesia. Finger-prick and venous blood samples were collected simultaneously from 782 individuals in order to compare the results obtained by the standard blood film method and the membrane filtration technique. Of the 782 blood-sampled inhabitants 69 (8.8%) were found mf positive. 39 (5%) were mf positive by both methods and 30 were mf positive by the membrane filtration technique only. In these latter 30 carriers the geometric mean mf count was 19.7 mf/ml, significantly lower than that of 651.1 mf/ml in the 39 carriers positive by both techniques. Using the membrane filtration technique, the mf carrier prevalence rate increased from 1.9% in the youngest age group (15-19 years) to 16.9% in the oldest (< or = 60 years) while using the blood film method, it increased from 1.3% to 12.7%. Roughly, when using the membrane filtration technique, the mf carrier prevalence rate was 1.77 higher than that found using the blood film method, considering either the whole population or successive age-groups. Moreover, when using the blood film method in the 40 years and more age group, the mf carrier prevalence rate was 10%, a proportion similar to the 8.8% prevalence rate determined by the membrane filtration technique in the whole population. Further studies are planned to assess whether the last finding may be confirmed in other Polynesian populations.(ABSTRACT TRUNCATED AT 250 WORDS)