MASS DEC CHEMOTHERAPY FOR CONTROL OF BANCROFTIAN FILARIASIS - COMPARATIVE EFFICACY OF 4 STRATEGIES 2 YEARS AFTER START OF TREATMENT

The efficacy of 4 strategies for control of bancroftian filariasis usi ng mass diethylcarbamazine (DEC) chemotherapy was evaluated and compar ed in 4 endemic communities in Tanzania 2 years after the start of tre atment. The strategies used were the standard 12 d treatment (strategy I), a semi-annual single dose treatment (strategy II), a monthly low dose treatment (strategy III), and DEC medicated salt (strategy IV). T reatment took place during the first study year, and no treatment was given during the second year. Among individuals who were microfilaraem ic before treatment, the microfilaria (mf) clearance rates were 41.5%, 75.0%, 84.0% and 89.1%, and the pre-treatment mf geometric mean inten sities (GMIs) were reduced by 97.1%, 98.9%, 99.8% and 99.8%, for strat egies I, II, III and IV, respectively, 2 years after starting treatmen t. Statistical analysis indicated that strategies III and IV were equa lly effective, and superior in clearing microfilaraemias and in reduci ng mf GMIs compared to strategies I and II; strategy II was significan tly more effective than strategy I. The rate of occurrence of new case s of microfilaraemia among individuals who were amicrofilaraemic durin g the pre-treatment surveys was negligible over the study period in al l communities. In all the communities combined, 66.6% of males present ing hydrocele before treatment, and 61.5% of individuals presenting el ephantiasis before treatment, showed improvements in these conditions 2 years after the start of treatment, either as a reduction in size or complete disappearance.