Viability and fertility of adult Onchocerca volvulus after 6 years of treatment with ivermectin.
Onchocerca volvulus nodules were removed from 77 fully compliant patients in a longitudinal study of ivermectin treatment in Sierra Leone. The patients had participated in a randomized controlled trial and received either 4 annual doses of ivermectin or 10 6-monthly doses over 6 years. Worms were examined 9 months after the last treatment for evidence of changes in morphology, viability and reproductivity. The findings were compared with results for the 2 groups obtained at earlier surveys of the same study population. Repeated treatment at 6 and 12-month intervals has resulted in a marked ageing of the male worm population profile and a significant reduction in the proportion of live female worms found in the nodules. In addition, there has been a reduction in reproductivity of 90% or more. However, most of the worms found were still alive and potentially fertile, underlining the need for the continuation of regular ivermectin treatment to maintain the benefits achieved.
Department of Biological Sciences, Keele University, Staffordshire, UK.
S L
SL
Kläger
J A
JA
Whitworth
M D
MD
Downham
D000328:Adult; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005298:Fertility / Q000187:drug effects; D006801:Humans; D007559:Ivermectin / Q000627:therapeutic use*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D017181:Onchocerca volvulus / Q000187:drug effects* / Q000254:growth & development; D009855:Onchocerciasis / Q000188:drug therapy*
D007559:Ivermectin