Serum microfilarial antibody titres before and after treatment of bancroftian microfilaraemia with diethylcarbamazine.

Eight Filipino patients with Wuchereria bancrofti microfilaraemia were treated with diethylcarbamazine. The intensity of microfilaraemia and titre of microfilarial agglutinating antibodies were measured over the ensuing six weeks. Nuclepore filtration of blood indicated clearing of microfilaraemia in five patients and a reduction in numbers in the other three. Several patterns of antibody response were observed. Five patients had high initial antibody titres; they did not change significantly after diethylcarbamazine therapy. Antibody was not detectable before treatment in three patients; elimination of microfilaraemia was associated with the appearance of antibody in two of the subjects, while microfilariae were not totally cleared and antibodies never appeared in the third patient. This study confirms that diethylcarbamazine is not always successful in the treatment of bancroftian microfilaraemia. It is consistent with, but does not prove, the hypothesis that the presence or absence of microfilariae and microfilarial antibodies depends upon the relative release of microfilariae into the bloodstream and the rate of synthesis of microfilarial antibodies.