Effect of aggressive prolonged diethylcarbamazine therapy on circulating antigen levels in bancroftian filariasis

BACKGROUND Single dose diethylcarbamazine (DEC) as used in control programm es is effectively microfilaricidal for periods of up to a year or more but has incomplete ability to kill Wuchereria bancrofti adult parasites. These regimens can be effective in breaking transmission by suppression of circul ating microfilariae available to mosquito vectors. Whether prolonged or agg ressive therapy with DEC has a significant effect on adult worms, which may live up to 12 years or more, and is important in the context of the treatm ent of individual patients, is still incompletely understood. METHODS In order to investigate the adulticidal effect of aggressive therap y, DEC was given at 6 mg/kg/day for 12-day courses at 0, 6, 12, and 18 mont hs and Og4C3 antigenaemia followed over two years in 38 CAg + Brazilians in a W. bancrofti endemic area. RESULTS At two year follow-up, the median level of antigenaemia was 21% of the pre-treatment value. 92% of individuals had antigen levels < 50% of pre treatment values, but only 26% had completely cleared antigenaemia. The cle arance rate at 24 months was only 12% (3/26) in the asymptomatic CAg + pati ents but 58% (7/12) in those with clinical manifestations of filariasis. Th e latter individuals cleared significantly more antigen (median of 0% pretr eatment antigenaemia vs. 26%; P = 0.02) than asymptomatic but infected indi viduals. CONCLUSION Aggressive repeated therapy with DEC alone is ineffective in con sistently eradicating adult W. bancrofti, especially in infected but asympt omatic individuals. prolonged courses of combination therapy with other ant ifilarial drugs should be investigated for treatment of individual patients with the means to pursue aggressive personal medical care.