Advertisement
Research Article

Dynamics of Onchocerca volvulus Microfilarial Densities after Ivermectin Treatment in an Ivermectin-naïve and a Multiply Treated Population from Cameroon

  • Sébastien D. S. Pion mail,

    sebastien.pion@ird.fr

    Affiliation: UMI 233, Institut de Recherche pour le Développement (IRD) and University of Montpellier 1, Montpellier, France

    X
  • Hugues C. Nana-Djeunga,

    Affiliation: General Biology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon

    X
  • Joseph Kamgno,

    Affiliation: Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1 and Filariasis & other Tropical Diseases Research Centre, Yaoundé, Cameroon

    X
  • Nicholas Tendongfor,

    Affiliations: Research Foundation in Tropical Diseases and the Environment, Buea, Cameroon, Department of Biochemistry and Microbiology, Faculty of Science, University of Buea, Buea, Cameroon

    X
  • Samuel Wanji,

    Affiliation: Research Foundation in Tropical Diseases and the Environment, Buea, Cameroon

    X
  • Flobert Njiokou,

    Affiliation: General Biology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon

    X
  • Roger K. Prichard,

    Affiliation: Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, Québec, Canada

    X
  • Michel Boussinesq

    Affiliation: UMI 233, Institut de Recherche pour le Développement (IRD) and University of Montpellier 1, Montpellier, France

    X
  • Published: February 28, 2013
  • DOI: 10.1371/journal.pntd.0002084

Reader Comments (1)

Post a new comment on this article

Explanation for differences between skin repopulation rates

Posted by luccoffeng on 16 Apr 2013 at 09:42 GMT

Dear authors,

Thank you for this interesting work, I enjoyed reading it. One of your main findings is the worms in multply-treated individuals seem to be less productive in terms of mf quantity, although they start producing earlier after ivermectin treatment. One of the possible explanations you discuss is genetic selection. I would just like to share my thoughts on this point.

Suppose that the duration of the embryostatic effect of ivermectin is not (entirely) determined by genetic selection but (also) by the magnitude of the plug of dead mf in the uteri of adult female worms. The more productive a worm at the time of exposure to ivermectin, the more clogged up the uteri get, and the longer it takes for the plug to resolve. After resolution of the plug can female worms be inseminated and produce mf again. Such a mechanism could explain why the multiply-treated individuals show earlier skin repopulation with mf, assuming that the worms in those individuals are less productive (through non-cumulative or cumulative effects of ivermectin). This would also fit the observation of relatively low mf skin densities in the multiply-treated individuals 180 days after ivermectin.

Kind regards,

Luc Coffeng

No competing interests declared.