Publications des scientifiques de l'IRD

Pion Sébastien, Nana-Djeunga H. C., Kamgno J., Tendongfor N., Wanji S., Njiokou F., Prichard R. K., Boussinesq Michel. (2013). Dynamics of Onchocerca volvulus microfilarial densities after ivermectin treatment in an ivermectin-naive and a multiply treated population from Cameroon. Plos Neglected Tropical Diseases, 7 (2), p. e2084. ISSN 1935-2735.

Titre du document
Dynamics of Onchocerca volvulus microfilarial densities after ivermectin treatment in an ivermectin-naive and a multiply treated population from Cameroon
Année de publication
2013
Type de document
Article référencé dans le Web of Science WOS:000315644900044
Auteurs
Pion Sébastien, Nana-Djeunga H. C., Kamgno J., Tendongfor N., Wanji S., Njiokou F., Prichard R. K., Boussinesq Michel
Source
Plos Neglected Tropical Diseases, 2013, 7 (2), p. e2084 ISSN 1935-2735
Background/Objective: Ivermectin has been the keystone of onchocerciasis control for the last 25 years. Sub-optimal responses to the drug have been reported in Ghanaian communities under long-term treatment. We assessed, in two Cameroonian foci, whether the microfilaricidal and/or embryostatic effects of ivermectin on Onchocerca volvulus have been altered after several years of drug pressure. Methods: We compared the dynamics of O. volvulus skin microfilarial densities after ivermectin treatment in two cohorts with contrasting exposure to this drug: one received repeated treatment for 13 years whereas the other had no history of large-scale treatments (referred to as controls). Microfilarial densities were assessed 15, 80 and 180 days after ivermectin in 122 multiply treated and 127 ivermectin-naive individuals. Comparisons were adjusted for individual factors related to microfilarial density: age and number of nodules. Findings: Two weeks post ivermectin, microfilarial density dropped equally (98% reduction) in the ivermectin-naive and multiply treated groups. Between 15 and 180 days post ivermectin, the proportion of individuals with skin microfilariae doubled (from 30.8% to 67.8%) in controls and quadrupled (from 19.8% to 76.9%) in multiply treated individuals but the mean densities remained low in both sites. In fact, between 15 and 80 days, the repopulation rate was significantly higher in the multiply treated individuals than in the controls but no such difference was demonstrated when extending the follow-up to 180 days. The repopulation rate by microfilariae was associated with host factors: negatively with age and positively with the number of nodules. Conclusion: These observations may indicate that the worms from the multi-treated area recover mf productivity earlier but would be less productive than the worms from the ivermectin-naive area between 80 and 180 days after ivermectin. Moreover, they do not support the operation of a strong cumulative effect of repeated treatments on the fecundity of female worms as previously described.
Plan de classement
Sciences fondamentales / Techniques d'analyse et de recherche [020] ; Santé : généralités [050] ; Entomologie médicale / Parasitologie / Virologie [052]
Description Géographique
CAMEROUN
Localisation
Fonds IRD [F B010060739]
Identifiant IRD
fdi:010060739
Contact