No abstract

To determine the frequency with which living adult Wuchereria bancrofti can be detected by ultrasound in the scrotal area of men with filarial infection, we used a 7.5 MHz transducer to perform weekly ultrasound examinations on 100 microfilaraemic men (18-34 years old) from Greater Recife, Brazil. The peculiar pattern of movement that characterizes the adult worm image on ultrasound (the filaria dance sign) was detected in the lymphatic vessels of the spermatic cord in 80 men (bilaterally in 29 men). Among 20 men with no filaria dance sign, the geometric mean microfilarial density was 68/mL, compared with 238/mL and 775/mL among those with unilateral and bilateral filaria dance signs, respectively (P = 0.0001). The lymphatic vessels of the spermatic cord appear to be a common, and perhaps the principal, site of adult W. bancrofti in men with asymptomatic microfilaraemia. Studies are needed to define the relationship between the presence of filarial worms in the scrotal area and the development of filaria-associated morbidity.

No abstract

The effectiveness of single oral doses of ivermectin (200 or 400 micrograms/kg) and diethylcarbamazine (DEC, 6 mg/kg), preceded 4 d earlier by either placebo or very small doses of these drugs, was compared, over a 2-year period, in a double-blind trial in 67 microfilaraemic Brazilian men with bancroftian filariasis. Regimens containing ivermectin alone decreased the number of microfilariae significantly faster and more effectively for the first month after treatment than regimens containing DEC alone, but the latter were significantly more effective throughout the second year after treatment (1.7-8.2% of pretreatment levels with DEC vs. 12.6-30.8% with ivermectin during that period); the higher ivermectin dose showed a tendency towards more effectiveness than the lower dose. Most effective was the combination of ivermectin (20 micrograms/kg) followed 4 d later by DEC (6 mg/kg), with reduction of microfilaraemia to 2.4% of pretreatment levels at 2 years. Adverse reactions were well tolerated with all regimens, the reactions being significantly more generalized (i.e., fever) following ivermectin and localized (i.e., scrotal inflammatory nodules around dying adult worms) following DEC. Further trials of single-dose combination therapy vs. single high doses of ivermectin or DEC should determine the ideal regimen for treatment and control of bancroftian filariasis.

SummarySince diethylcarbamazine, the drug recommended for treatment of lymphatic filariasis, seems only partially effective against the adult worm, intense interest persists in identifying a macrofilaricidal drug for this infection. To evaluate directly in vivo the macrofilaricidal activity of repeat high-dose ivermectin, I 5 men who had living adult Wuchereria bancrofti detected in the scrota1 area by ultrasound were treated with 400 pg/kg of ivermectin at 2-week intervals for 6 months (total dose, 4.8 mg/kg). Serial ultrasound examinations were performed before, during, and for 6 months after treatment. Profound suppression of microfilaraemia followed the first dose of ivermectin, but movements characteristic of the adult worm on ultrasound remained unchanged both in location and pattern. Even when given in total doses of 4.8 mg/kg, ivermectin appears to have no observable activity against adult W . bancrofti, although its ability to suppress microfilaraemia makes it potentially useful for the control of lymphatic filariasis.