Effects of Ivermectin and Diethylcarbamazine on Microfilariae and Overall Microfilaria Production in Bancroftian Filariasis

Abstract

Ivermectin and diethylcarbamazine (DEC) are used in mass treatment programs for the elimination of lymphatic filariasis because of their strong effects on microfilaremia. However, the effects of treatment on adult worms and the degree of individual variation in efficacy are unclear. We analyzed series of microfilaria (Mf) counts from individuals treated with a single dose of 400 microg/kg ivermectin or 6 mg/kg DEC (N = 23 in each group; 1 year follow-up). For each individual, we estimated the microfilaricidal effect and the reduction in overall Mf production (e.g., caused by death or sterilization of worms, or inhibited Mf release from the female worm uterus). Ivermectin on average killed 96% of Mf and reduced Mf production by 82%. DEC killed 57% of Mf and reduced Mf production by 67%, with some individuals responding very poorly. The strong reduction in overall Mf production is good news for control of lymphatic filariasis, but the prospects of elimination will be diminished if part of the population systematically responds poorly to treatment.

Current Evidence on the Use of Antifilarial Agents in the Management of bancroftian Filariasis

“…Regarding monotherapy with IVM, Stolk et al [21] demonstrated that single dose IVM alone can achieve a high microfilaria kill rate and a worm productivity loss at 1 year (96% and 82% on average, resp.). In comparison, the rates for the DEC treated group were very much lower (57% and 67%, resp.).…”

Ribosomal Protein S29 Regulates Metabolic Insecticide Resistance through Binding and Degradation of CYP6N3

“…Many new and re-emerging diseases are transmitted by mosquitoes, including malaria, dengue fever, yellow fever, filariasis, and West Nile fever [1], [2], [3], [4], [5]. Chemical control plays a major role in managing mosquito-borne diseases.…”

Successful Treatment of Brugia pahangi in Naturally Infected Cats with Ivermectin

“…The results of the present study indicated that adult worms were possibly affected by ivermectin by sterilization of female worms resulting in a decrease of microfilaremia. A similar effect was reported for Wuchereria bancrofti [8]. Therefore, it seems that the main target of ivermectin is reproduction of filarial worms, as the drug impairs embryogenesis and decrease microfilaremia [4,7,16].…”

“…In control program for filariasis, ivermectin is the drug of choice, especially in areas with onchocercosis [5]. There are several studies about the efficacy of ivermectin against filarial worms [1,6-8]. For Onchocerca volvulus , treatment with ivermectin reduces microfilarial motility in vitro [9], and embryogenesis is impaired in adult female worms [6].…”