ASSESSMENT OF THE EFFICACY OF DIETHYLCARBAMAZINE ON ADULT WUCHERERIA-BANCROFTI IN-VIVO

To assess directly the effect of various doses of diethylcarbamazine ( DEC) on adult Wuchereria bancrofti, 31 infected men were randomly assi gned to receive an initial single DEC dose of 1 mg/kg (n=7), 6 mg/kg ( n=10), or 12 mg/kg (n=14). Beginning 7 d later, the dosage of DEC and duration of treatment were progressively increased for 7-10 weeks. Phy sical examinations were performed to detect scrotal nodules and the sc rotal area was examined by ultrasound (7.5 MHz transducer) to monitor the 'filaria dance sign' (FDS), the characteristic pattern of adult wo rm movement. Of 53 adult worm 'nests' that were detected by ultrasound , 22 (41.5%) were DEC-sensitive (FDS became non-detectable and a nodul e became palpable at the site); 20 (37.7%) were not sensitive (FDS rem ained unchanged and detectable and no nodule developed), and 11 (20.8% ) showed mixed responses (FDS remained detectable but a palpable nodul e developed). All but one sensitive or mixed response occurred within 1 week after the initial single dose. Of 39 'nests' in men who initial ly received a single 6 or 12 mg/kg dose of DEC, 20 (51.3%) had sensiti ve responses compared to 2 (14.3%) of 14 'nests' in men who received a single 1 mg/kg dose (P=0.04). Above 6 mg/kg, the macrofilaricidal eff ect of DEC did not increase with dose a significant proportion of adul t W. bancrofti were nor susceptible to DEC during the study period.