Failure of diethylcarbamazine as a provocative test in subperiodic Wuchereria bancrofti filariasis.

The effect of diethylcarbamazine (DEC) on levels of microfilaraemia in 70 patients with subperiodic, Pacific-variant Wuchereria bancrofti infection was studied one hour after oral administration of 5 mg/kg of drug. In contrast to the immediate DEC-induced increase in microfilaraemia which had been previously described in patients with nocturnally periodic filariasis, diethylcarbamazine failed to elicit such a response in patients with subperiodic bancrofti infection. Indeed, one hour after oral DEC the number of circulating microfilariae was reduced to about 8% of pre-treatment values.