Long-term effect of diethylcarbamazine citrate on microfilaraemia status in treated individuals

Follow up of microfilaraemic individuals infected with Wuchereria bancrofti at five years after treatment was carried out in a tea workers population. Diethylcarbamazine citrate in the dose schedule of 72 mg/kg body weight given in equal daily doses over a period of 21 days cleared 51.6 per cent microfilaraemic individuals five year post-treatment. Eighty five subjects were successfully followed and among these, 10 (11.8%) showed increase in mf counts, 31 (36.4%) showed reduction but remained microfilaraemic and 44 (51.8%) became amicrofilaraemic. The age and sex of the host had no significant effect on the clearance of mf. Persistence of a relatively stable low number of mf in treated individuals is more likely due to survival of one or more female worms after the therapy or due to reinfection which could not be ruled out in the present study. Overall, findings indicated that diethylcarbamazine citrate appeared to give a long-term benefit to treated individuals.