Efficacy of mass single-dose diethylcarbamazine and DEC-fortified salt against bancroftian filariasis in Papua New Guinea six months after treatment.

The efficacy of two diethylcarbamazine (DEC) treatment strategies to control bancroftian filariasis, diethylcarbamazine-fortified salt (DEC-FS) and a single DEC dose on mass administration, was evaluated in two communities in Papua New Guinea with pretreatment antigen prevalence of 55% and 71%. In the first community 0.2% w/w diethylcarbamazine-fortified salt was distributed monthly to accepting households at no cost for 12 months. In the second community a single DEC dose based on body size but designed to give about 6 mg/kg was administered to eligible acceptors. Despite wide variation in antigen prevalence among study villages there were marked reductions in prevalences under both treatment strategies. Among individuals antigenaemic on day 0, DEC-FS and a single DEC dose gave filaria antigen clearance rates of 43% and 13%, respectively. In the salt-treated community the incidence of antigenaemia after 6 months in acceptors from households that received 5 kg or more of DEC-FS was 14% whereas in those receiving less than 5 kg salt was 4%. The incidence rates in the second community in those that received < 2.5 and > or = 2.5 tablets were 16% and 8%, respectively. The two treatment strategies were simple to manage and appropriate for developing countries and were widely accepted. DEC-FS was more efficacious than single-dose DEC tablets but a single administration of DEC tablets is easier to administer.