Recent studies have shown that single doses of diethylcarbamazine (DEC) have the same long-term (1-year) effect in decreasing microfilaremia as the formerly-recommended 12-day regimens of DEC and, even more importantly, that the use of single doses of 2 drugs administered concurrently (optimally albendazole or ivermectin with DEC) is 99% effective in removing microfilarias from the blood.