Evaluation of the diethylcarbamazine provocative test in the diagnosis of Wuchereria bancrofti infections in the Nigerian savanna and the effects on Dipetalonema perstans.

Large scale filariasis surveys in rural areas for microfilaraemia, especially of periodic types such as Wuchereria bancrofti are known to cause considerable administrative, technical and social problems. The present investigation was carried out in the population of two villages in the Malumfashi district of the Northern Nigerian savanna. From the survey results, the sensitivity and specificity of two techniques-day-time diethylcarbamazine (DEC) provocative test by blood smear and concentration, and night-blood examination by smear and concentration especially for W. bancrofti-were assessed. Day-time DEC provocative test proved to be efficient in terms of sensitivity and specificity, compared with the night-blood method, for W. bancrofti detection but less so for Dipetalonema perstans, the other blood microfilaria found in this population during these studies. A regression line between night-blood survey results for W. bancrofti and the results from day-time DEC provocative test was calculated. With the help of this regression line it is possible to estimate W. bancrofti microfilarial prevalence for night surveys, using the DEC provocative test results of day-time surveys. This can be done with minimal, but known, loss of accuracy and incurs fewer administrative, technical and social difficulties.