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Bouaké, Ivory Coast

Jamonneau V.,CIRDES Center International Of Recherche Developpement Sur Lelevage En Zone Sub Humide | Jamonneau V.,CIRAD - Agricultural Research for Development | Camara O.,Programme National de Lutte contre la Trypanosomose Humaine Africaine | Ilboudo H.,CIRDES Center International Of Recherche Developpement Sur Lelevage En Zone Sub Humide | And 9 more authors.
PLoS Neglected Tropical Diseases | Year: 2015

Individual rapid tests for serodiagnosis (RDT) of human African trypanosomiasis (HAT) are particularly suited for passive screening and surveillance. However, so far, no large scale evaluation of RDTs has been performed for diagnosis of Trypanosoma brucei gambiense HAT in West Africa. The objective of this study was to assess the diagnostic accuracy of 2 commercial HAT-RDTs on stored plasma samples from West Africa. SD Bioline HAT and HAT Sero-K-Set were performed on 722 plasma samples originating from Guinea and Côte d’Ivoire, including 231 parasitologically confirmed HAT patients, 257 healthy controls, and 234 unconfirmed individuals whose blood tested antibody positive in the card agglutination test but negative by parasitological tests. Immune trypanolysis was performed as a reference test for trypanosome specific antibody presence. Sensitivities in HAT patients were respectively 99.6% for SD Bioline HAT, and 99.1% for HAT Sero-K-Set, specificities in healthy controls were respectively 87.9% and 88.3%. Considering combined positivity in both RDTs, increased the specificity significantly (p≤0.0003) to 93.4%, while 98.7% sensitivity was maintained. Specificities in controls were 98.7–99.6% for the combination of one or two RDTs with trypanolysis, maintaining a sensitivity of at least 98.1%. The observed specificity of the single RDTs was relatively low. Serial application of SD Bioline HAT and HAT Sero-K-Set might offer superior specificity compared to a single RDT, maintaining high sensitivity. The combination of one or two RDTs with trypanolysis seems promising for HAT surveillance. © 2015 Jamonneau et al.


Koffi A.A.,Institute Pierre Richet IPR | Ahoua Alou L.P.,Felix Houphouet-Boigny University | Adja M.A.,Felix Houphouet-Boigny University | Chandre F.,IRD Montpellier | Pennetier C.,IRD Montpellier
Malaria Journal | Year: 2013

Background: An experimental hut station built at M'Bé in 1998 was used for many years for the evaluation of insecticidal product for public health until the civil war broke out in 2002. Breeding sites of mosquitoes and selection pressure in the area were maintained by local farming practices and the West African Rice Development Association (WARDA, actually AfricaRice) in a large rice growing area. Ten years after the crisis, bioassays, molecular and biochemical analyses were conducted to update the resistance status and study the evolution of resistance mechanisms of Anopheles gambiae s.s population. Methods. Anopheles gambiae s.s larvae from M'Bé were collected in breeding sites and reared until emergence. Resistance status of this population to conventional insecticides was assessed using WHO bioassay test kits for adult mosquitoes, with 10 insecticides belonging to pyrethroids, pseudo-pyrethroid, organochlorides, carbamates and organophosphates with and without the inhibitor piperonyl butoxyde (PBO). Molecular and biochemical assays were carried out to identify the L1014F kdr, L1014S kdr and ace-1 §ssup§ R §esup§ alleles in individual mosquitoes and to detect potential increase in mixed function oxidases (MFO) level, non-specific esterases (NSE) and glutathione S-transferases (GST) activities. Results and discussion. Anopheles gambiae s.s from M'Bé exerted high resistance levels to organochlorides, pyrethroids, and carbamates. Mortalities ranged from 3% to 21% for organochlorides, from 50% to 75% for pyrethroids, 34% for etofenprox, the pseudo-pyrethroid, and from 7% to 80% for carbamates. Tolerance to organophosphates was observed with mortalities ranging from 95% to 98%. Bioassays run with a pre-exposition of mosquitoes to PBO induced very high levels of mortalities compared to the bioassays without PBO, suggesting that the resistance to pyrethroid and carbamate relied largely on detoxifying enzymes' activities. The L1014F kdr allelic frequency was 0.33 in 2012 compared to 0.05 before the crisis in 2002. Neither the L1014S kdr nor ace-1 §ssup§ R §esup§ mutations were detected. An increased activity of NSE and level of MFO was found relative to the reference strain Kisumu. This was the first evidence of metabolic resistance based resistance in An. gambiae s.s from M'Bé. Conclusion: The An. gambiae s.s population showed very high resistance to organochlorides, pyrethroids and carbamates. This resistance level relied largely on two major types of resistance: metabolic and target-site mutation. This multifactorial resistance offers a unique opportunity to evaluate the impact of both mechanisms and their interaction with the vector control tools currently used or in development. © 2013 Koffi et al.; licensee BioMed Central Ltd.


Koffi A.A.,Institute Pierre Richet IPR | Alou L.P.A.,University Of Cocody | Adja M.A.,University Of Cocody | Kone M.,Institute Pierre Richet IPR | And 2 more authors.
Parasites and Vectors | Year: 2012

Background: At Yaokoffikro field site near Bouaké, in central Côte d'Ivoire, a group of experimental huts built in 1996 served over many years for the evaluation of insecticides against highly resistant mosquitoes. Breeding sites of mosquitoes and selection pressure in the area were maintained by local farming practices until a war broke out in September 2002. Six years after the crisis, we conducted bioassays and biochemical analysis to update the resistance status of Anopheles gambiae s.s. populations and detect other potential mechanisms of resistance that might have evolved. Methods. An. gambiae s.s. larvae from Yaokoffikro were collected in breeding sites and reared to adults. Resistance status of this population to insecticides was assessed using WHO bioassay test kits for adult mosquitoes with seven insecticides: two pyrethroids, a pseudo-pyrethroid, an organochloride, two carbamates and an organophosphate. Molecular and biochemical assays were carried out to identify the L1014F kdr and ace-1 R alleles in individual mosquitoes and to detect potential increase in mixed function oxidases (MFO), non-specific esterases (NSE) and glutathione S-transferases (GST) activity. Results: High pyrethroids, DDT and carbamate resistance was confirmed in An. gambiae s.s. populations from Yaokoffikro. Mortality rates were less than 70% with pyrethroids and etofenprox, 12% with DDT, and less than 22% with the carbamates. Tolerance to fenitrothion was observed, with 95% mortality after 24 h. PCR analysis of samples from the site showed high allelic frequency of the L1014F kdr (0.94) and the ace-1 R (0.50) as before the crisis. In addition, increased activity of NSE, GST and to a lesser extent MFO was found relative to the reference strain Kisumu. This was the first report detecting enhanced activity of these enzymes in An. gambiae s.s from Yaokoffikro, which could have serious implications in detoxification of insecticides. Their specific roles in resistance should be investigated using additional tools. Conclusion: The insecticide resistance profile at Yaokoffikro appears multifactorial. The site presents a unique opportunity to evaluate its impact on the protective efficacy of insecticidal products as well as new tools to manage these complex mechanisms. It calls for innovative research on the behaviour of the local vector, its biology and genetics that drive resistance. Copyright © 2012 Koffi et al; licensee BioMed Central Ltd.


Koffi A.A.,Institute Pierre Richet IPR | Ahoua Alou L.P.,Institute Pierre Richet IPR | Djenontin A.,Institute Of Recherche Pour Le Developpement Ird | Djenontin A.,University Abomey Calavi | And 5 more authors.
Parasite | Year: 2015

Pyrethroid resistance in malaria vectors has spread across sub-Saharan Africa. Alternative tools and molecules are urgently needed for effective vector control. One of the most promising strategies to prevent or delay the development of resistance is to use at least two molecules having unrelated modes of action in combination in the same bed net. We evaluated in experimental huts in Côte d'Ivoire, a new polyethylene long-lasting insecticidal net (LN) product, Olyset® Duo, incorporating permethrin (PER) and pyriproxyfen (PPF), an insect growth regulator (IGR). PPF alone or in combination with permethrin had a significant impact on fertility (7-12% reduction relative to control) and no effect on fecundity of wild multi-resistant An. gambiae s.s. These results triggered crucial research questions on the behaviour of targeted mosquitoes around the LN. To maximize the sterilizing effect of PPF in the combination, there would be a need for a trade-off between the necessary contact time of the insect with PPF and the surface content of the pyrethroid insecticide that is bioavailable and induces excito-repellency. © A.A. Koffi et al., published by EDP Sciences, 2015.


Djenontin A.,University Abomey Calavi | Djenontin A.,Institute Of Recherche Pour Le Developpement Ird | Ahoua Alou L.P.,Institute Pierre Richet IPR | Koffi A.,Institute Pierre Richet IPR | And 5 more authors.
Parasite | Year: 2015

In the context of the widespread distribution of pyrethroid resistance among malaria vectors, we did a release-recapture trial in experimental huts to investigate the insecticidal and sterilizing effects of a novel long-lasting net (LN), Olyset® Duo, incorporating a mixture of permethrin (PER) and the insect growth regulator (IGR), pyri-proxyfen (PPF). An LN containing PPF alone and a classic Olyset® Net were tested in parallel as positive controls. The effect of progressive number of holes (6, 30, or 150) that may accrue in nets over time was simulated. We used two laboratory Anopheles gambiae s.s. strains: the susceptible Kisumu strain and the pyrethroid-resistant VK-Per strain having solely kdr as resistance mechanism. The effect of these nets on the reproductive success of blood-fed females that survived the different LNs conditions was recorded. Regardless of the mosquito strain, the LNs containing PPF alone with as many as 30 holes drastically reduced the number of eggs laid by females succeeding in feeding, i.e. fecundity by 98% and egg hatching rate (fertility) by 93% relative to untreated control net. Very few of the resistant females blood fed and survived under the Olyset® Duo with similar number of holes (up to 30) but of these few, the inhibition of reproductive success was 100%. There was no evidence that the Olyset® Duo LN with 150 holes impacted fecundity or fertility of the resistant colony. The efficacy of Olyset® Duo is encouraging and clearly illustrates that this new net might be a promising tool for malaria transmission control and resistance management. © A. Djènontin et al., published by EDP Sciences, 2015.

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