Diethylcarbamazine in the control of splenomegaly associated with Bancroftian filariasis in the Ok Tedi area of Papua New Guinea.

Bancroftian filariasis is highly endemic in the Ok Tedi region of Papua New Guinea, with a reported mean rate of 39% before the implementation of a single-dose diethylcarbamazine (DEC) treatment programme in 1986. This was followed by a 72% decline in the rate of detectable microfilaraemia and a 40% reduction in pre- and post-treatment splenomegaly. No significant difference was observed when spleen enlargement was compared to the presence of patent malaria. A significant difference in splenomegaly was observed between DEC-treated villagers and their untreated counterparts. Significant differences were reported in the rate of detectable microfilariae of Wuchereria bancrofti, but not of malaria, between the two groups. The number of DEC administrations and the period of time since the first treatment played a significant role immunologically. Significant differences were observed in immunoglobulin (Ig) M and IgG levels and in the extent of splenomegaly between DEC-treated and untreated areas. Filarial infection associated with malaria resulted in higher spleen rates and size. W. bancrofti is a major contributor to splenomegaly in the Ok Tedi region, and splenomegaly associated with bancroftian filariasis can be reduced or controlled by low, well-spaced doses of DEC.