Dynamics of Onchocerca volvulus microfilarial densities after ivermectin treatment in an ivermectin-naïve and a multiply treated population from Cameroon.
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 effec...
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ftdoajarticles:oai:doaj.org/article:8b58a62a73e543f58d42ee0560679813 2023-05-15T15:15:06+02:00 Dynamics of Onchocerca volvulus microfilarial densities after ivermectin treatment in an ivermectin-naïve and a multiply treated population from Cameroon. Sébastien D S Pion Hugues C Nana-Djeunga Joseph Kamgno Nicholas Tendongfor Samuel Wanji Flobert Njiokou Roger K Prichard Michel Boussinesq 2013-01-01T00:00:00Z https://doi.org/10.1371/journal.pntd.0002084 https://doaj.org/article/8b58a62a73e543f58d42ee0560679813 EN eng Public Library of Science (PLoS) http://europepmc.org/articles/PMC3585010?pdf=render https://doaj.org/toc/1935-2727 https://doaj.org/toc/1935-2735 doi:10.1371/journal.pntd.0002084 1935-2727 1935-2735 https://doaj.org/article/8b58a62a73e543f58d42ee0560679813 PLoS Neglected Tropical Diseases, Vol 7, Iss 2, p e2084 (2013) Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 article 2013 ftdoajarticles https://doi.org/10.1371/journal.pntd.0002084 2022-12-30T23:38:24Z 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-naïve 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-naïve 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-naïve 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 ... Article in Journal/Newspaper Arctic Directory of Open Access Journals: DOAJ Articles Arctic PLoS Neglected Tropical Diseases 7 2 e2084 |
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Directory of Open Access Journals: DOAJ Articles |
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ftdoajarticles |
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English |
topic |
Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 |
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Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 Sébastien D S Pion Hugues C Nana-Djeunga Joseph Kamgno Nicholas Tendongfor Samuel Wanji Flobert Njiokou Roger K Prichard Michel Boussinesq Dynamics of Onchocerca volvulus microfilarial densities after ivermectin treatment in an ivermectin-naïve and a multiply treated population from Cameroon. |
topic_facet |
Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 |
description |
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-naïve 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-naïve 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-naïve 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 ... |
format |
Article in Journal/Newspaper |
author |
Sébastien D S Pion Hugues C Nana-Djeunga Joseph Kamgno Nicholas Tendongfor Samuel Wanji Flobert Njiokou Roger K Prichard Michel Boussinesq |
author_facet |
Sébastien D S Pion Hugues C Nana-Djeunga Joseph Kamgno Nicholas Tendongfor Samuel Wanji Flobert Njiokou Roger K Prichard Michel Boussinesq |
author_sort |
Sébastien D S Pion |
title |
Dynamics of Onchocerca volvulus microfilarial densities after ivermectin treatment in an ivermectin-naïve and a multiply treated population from Cameroon. |
title_short |
Dynamics of Onchocerca volvulus microfilarial densities after ivermectin treatment in an ivermectin-naïve and a multiply treated population from Cameroon. |
title_full |
Dynamics of Onchocerca volvulus microfilarial densities after ivermectin treatment in an ivermectin-naïve and a multiply treated population from Cameroon. |
title_fullStr |
Dynamics of Onchocerca volvulus microfilarial densities after ivermectin treatment in an ivermectin-naïve and a multiply treated population from Cameroon. |
title_full_unstemmed |
Dynamics of Onchocerca volvulus microfilarial densities after ivermectin treatment in an ivermectin-naïve and a multiply treated population from Cameroon. |
title_sort |
dynamics of onchocerca volvulus microfilarial densities after ivermectin treatment in an ivermectin-naïve and a multiply treated population from cameroon. |
publisher |
Public Library of Science (PLoS) |
publishDate |
2013 |
url |
https://doi.org/10.1371/journal.pntd.0002084 https://doaj.org/article/8b58a62a73e543f58d42ee0560679813 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
PLoS Neglected Tropical Diseases, Vol 7, Iss 2, p e2084 (2013) |
op_relation |
http://europepmc.org/articles/PMC3585010?pdf=render https://doaj.org/toc/1935-2727 https://doaj.org/toc/1935-2735 doi:10.1371/journal.pntd.0002084 1935-2727 1935-2735 https://doaj.org/article/8b58a62a73e543f58d42ee0560679813 |
op_doi |
https://doi.org/10.1371/journal.pntd.0002084 |
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PLoS Neglected Tropical Diseases |
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7 |
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2 |
container_start_page |
e2084 |
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