Insecticide resistance status in Anopheles gambiae in southern Benin

BACKGROUND: The emergence of pyrethroid resistance in Anopheles gambiae has become a serious concern to the future success of malaria control. In Benin, the National Malaria Control Programme has recently planned to scaling up long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) for malaria prevention. It is, therefore, crucial to monitor the level and type of insecticide resistance in An. gambiae, particularly in southern Benin where reduced efficacy of insecticide-treated nets (ITNs) and IRS has previously been reported. METHODS: The protocol was based on mosquito collection during both dry and rainy seasons across forty districts selected in southern Benin. Bioassay were performed on adults collected from the field to assess the susceptibility of malaria vectors to insecticide-impregnated papers (permethrin 0.75%, delthamethrin 0.05%, DDT 4%, and bendiocarb 0.1%) following WHOPES guidelines. The species within An. gambiae complex, molecular form and presence of kdr and ace-1 mutations were determined by PCR. RESULTS: Strong resistance to permethrin and DDT was found in An. gambiae populations from southern Benin, except in Aglangandan where mosquitoes were fully susceptible (mortality 100%) to all insecticides tested. PCR showed the presence of two sub-species of An. gambiae, namely An. gambiae s.s, and Anopheles melas, with a predominance for An. gambiae s.s (98%). The molecular M form of An. gambiae was predominant in southern Benin (97%). The kdr mutation was detected in all districts at various frequency (1% to 95%) whereas the Ace-1 mutation was found at a very low frequency (<or= 5%). CONCLUSION: This study showed a widespread resistance to permethrin in An. gambiae populations from southern Benin, with a significant increase of kdr frequency compared to what was observed previously in Benin. The low frequency of Ace-1 recorded in all populations is encouraging for the use of bendiocarb as an alternative insecticide to pyrethroids for IRS in Benin

Premier cas de chronobiologie des émissions cercariennes de type infradien chez Schistosoma mansoni dans deux foyers du Sud Bénin

International audienceLa schistosomose constitue au Bénin un réel problème de santé publique comme dans la plupart des autres pays africains. L'étude de la chronobiologie des émissions cercariennes horaires de deux populations de Schistosoma mansoni du sud-Bénin révèle, aussi bien en conditions de laboratoire qu'en conditions naturelles, un rythme particulier d'émission de type infradien avec 3 périodes de production : à l'aube entre 6 heures et 8 heures (Heure Locale, HL), en milieu de journée entre 09 heures et 15 ou 16 heures (HL) et le soir entre 17 heures et 20 heures (HL). Ce rythme d'émission est contraire à celui du type circadien, avec un seul pic d'émission, connu à ce jour pour les schistosomes de ce groupe. Ces deux populations de schistosomes ont été soumises à une pression sélective de même nature induisant des modifications dans le sens de l'harmonisation des processus de transmission du parasite à l'hôte vertébré. Une étude ultérieure permettra de mieux apprécier les causes de la modification du rythme circadien au type infradien

Evaluation préliminaire de la morbitité liée à S. haematobium et à S. mansoni dans la zone du futur barrage d'Adjarala au Bénin

L'objectif de cette étude était de procéder à une évaluation préliminaire de la morbidité liée aux schistosomoses dans la zone du barrage d'Adjarala au Bénin. Nous avons tiré au sort 412 enfants scolarisés de cinq villages. L'âge moyen des enfants était de 9,4 + 2,3 ans et le sex ratio (F/M) de 0,94. Ces enfants ont subi un examen parasitologique après filtrations des urines, un test des urines à la bandelette réactive à la recherche de micro-hématurie et de protéinurie, un examen macroscopique de l'aspect des urines, un examen de selle par la technique de Kato et une échographie de l'arbre urinaire. Nous avons par ailleurs procédé à une prospection malacologique au niveau des points de transmission de tous les villages visités en vue de l'identification des hôtes intermédiaires responsables de la transmission des schistosomoses dans la zone. Les deux formes de bilharzioses à #S. mansoni et à #S. haematobium ont été mises en évidence dans la zone. La bilharziose urinaire se présente sur un mode méso-endémique (19,7% de prévalence) tandis que la bilharziose à #S. mansoni$se présente sur un mode hypo-endémique (3,9$ et #Bulinus globosus$ dans la zone. (Résumé d'auteur

Dramatically decreased therapeutic efficacy of chloroquine and sulfadoxine-pyrimethamine, but not mefloquine, in southern Benin

Objective To evaluate the in vivo therapeutic efficacy of chloroquine (CQ), sulfadoxine-pyrimethamine (SP) and mefloquine (MQ) in children presenting with uncomplicated malaria in Benin. Methods Drug efficacy was tested according to the WHO in vivo 28-day protocol. For failures that occurred after 7 days of follow-up, paired pre- and post-treatment blood samples were genotyped at msp1 and msp2 loci to distinguish new infections and recrudescent strains. Children enrolled were randomly assigned to a therapeutic group (CQ, n = 14; SP, n = 42; MQ, n = 44). The number of CQ treatment was intentionally restricted after 1 month, as its use was considered to constitute a danger for children. Results Chloroquine and SP showed very high failure rates (85.7% and 50%, respectively), whereas MQ treatment was successful in 97.5%. The molecular tool allowed to re-evaluate two new infections previously considered as failures. Conclusions Chloroquine should no longer be used to treat children presenting with Plasmodium falciparum malaria in Benin

Prevalence des parasitoses intestinales au CNHU-HKM de Cotonou, Sud du Benin de 2003 a 2015

Objectif: Décrire l’évolution de la prévalence des parasitoses intestinales au CNHU-HKM de Cotonou de 2003 à 2015.Méthodes: une étude transversale descriptive à collecte rétrospective a été réalisée au laboratoire de Parasitologie – Mycologie du CNHU – HKM de Cotonou. Tous les patients ayant bénéficié d’une coprologie parasitaire du 1er janvier 2003 au 31 décembre 2015 ont été systématiquement inclus. Les variables (âge, sexe, année, statut hospitalisé ou externe, coprologie parasitaire positive et espèce parasitaire identifiée) ont été renseignées grâce aux registres de paillasse du laboratoire. Les techniques de Willis et de Bailenger ont été effectuées sur des selles recueillies dans un pot stérile acheminé dans un délai de moins de quatre heures au laboratoire.Résultats: Sur 8878 patients inclus, 1563 avaient une coprologie parasitaire positive soit une prévalence globale de 17,6%. La prévalence la plus élevée était obtenue en 2004 (28,5 %) et la plus basse en 2014 (3,8 %). Les protozoaires représentaient 98,1 % et les helminthes 1,9 %. Les protozoaires les plus retrouvés étaient Entamoeba histolytica (32,5 %), Blastocystis hominis (26,4 %) et Entamoeba coli (11,3 %). Les principaux helminthes étaient Ancylostoma et ou Necator (0,5 %) Dicrocoelium dendriticum (0,5 %) et Strongyloïdes stercoralis (0,4 %).Le monoparasitisme représentait 82,5% des cas suivi du biparasitisme (15,7 %) et du triparasitisme (1,7 %). Les associations les plus fréquentes étaient Blastocystis hominis + Entamoeba histolytica/dispar (20,1 %), Entamoeba coli + Entamoeba histolytica/dispar (17,2 %) et Blastocystis hominis + Endolimax nana (11,7 %).Conclusion: Probablement du fait des campagnes de distribution d’antihelminthiques et du déparasitage systématique, la prévalence des helminthoses digestives est plus faible que celle des protozooses. Le renforcement des mesures d’hygiène et des stratégies de lutte est une nécessité.Mots clés: Parasitoses intestinales, prévalences, Bénin, Afrique de l’OuestEnglish Title: Prevalence of intestinal parasitic infections in HKM University Hospital of Cotonou from 2003 to 2015 in southern BeninEnglish AbstractObjective: To describe the evolution of prevalence of intestinal parasitic infections in the national and university hospital of Cotonou.Methods: A retrospective study was performed at the Parasitology - Mycology laboratory in the National University Hospital of Cotonou from January 2003 to December 2015. Patients were selected by systematic random sampling method. Fresh stool samples were collected from each patient and processed by Willis and Bailenger fecal concentration technique. The data were saved with Excel 2007 software and exported to STATA 12.1 software for statistical analysis process. The Pearson Chi2 test was used to compare the averages. The statistical significance level was set at 5% (p value &lt; 0.05).Results: Among the 8878 patients included, 1563 (17.6% of overall prevalence) were infected by one or more intestinal parasites. The highest prevalence was noted in 2004 (28.5%) and the lowest in 2014 (3.8%). Protozoa accounted for 98.1 % and helminths for 1.9%. The most common protozoa were Entamoeba histolytica (32.5%), Blastocystis hominis (26.4%) and Entamoeba coli (11.3%). The main helminths were Ancylostoma and or Necator (0.5 %), Dicrocoelium dendriticum (0.5%) and Strongyloides stercoralis (0.4%). Monoparasitism accounted for 82.5% of the cases followed by biparasitism (246 cases, 15.7%) and triparasitism (27 cases, 1.7%). The most frequent associations were Blastocystis hominis + Entamoeba histolytica / dispar (20.1%), Entamoeba coli + Entamoeba histolytica / dispar (17.2%) and Blastocystis hominis + Endolimax nana (11.7%).Conclusion: Probably the distribution of antihelminthics to children and systematic deworming lowered the prevalence of digestive helminthosis than that of protozoa. Strengthening hygiene is necessary to control them.Keywords: Intestinal parasites, prevalence, Benin, West Afric

Impact of long-lasting, insecticidal nets on anaemia and prevalence of Plasmodium falciparum among children under five years in areas with highly resistant malaria vectors

Background: The widespread use of insecticide-treated nets (LLINs) leads to the development of vector resistance to insecticide. This resistance can reduce the effectiveness of LLIN based interventions and perhaps reverse progress in reducing malaria morbidity. To prevent such difficulty, it is important to know the real impact of resistance in the effectiveness of mosquito nets. Therefore, an assessment of LLIN efficacy was conducted in malaria prevention among children in high and low resistance areas. Methods: The study was conducted in four rural districts and included 32 villages categorized as low or high resistance areas in Plateau Department, south-western Benin. Larvae collection was conducted to measure vector susceptibility to deltamethrin and knockdown resistance (kdr) frequency. In each resistance area, around 500 children were selected to measure the prevalence of malaria infection as well as the prevalence of anaemia associated with the use of LLINs. Results: Observed mortalities of Anopheles gambiae s. s population exposed to deltamethrin ranged from 19 to 96%. Knockdown resistance frequency was between 38 and 84%. The prevalence of malaria infection in children under five years was 22.4% (19.9-25.1). This prevalence was 17.3% (14.2-20.9) in areas of high resistance and 27.1% (23.5-31.1) in areas of low resistance (p = 0.04). Eight on ten children that were aged six - 30 months against seven on ten of those aged 31-59 months were anaemic. The anaemia observed in the six to 30-month old children was significantly higher than in the 31-59 month old children (p = 0.00) but no difference associated with resistance areas was observed (p = 0.35). The net use rate was 71%. The risk of having malaria was significantly reduced (p < 0.05) with LLIN use in both low and high resistance areas. The preventive effect of LLINs in high resistance areas was 60% (95% CI: 40-70), and was significantly higher than that observed in low resistance areas (p < 0.05). Conclusion: The results of this study showed that the resistance of malaria vectors seems to date not have affected the impact of LLINs and the use of LLINs was highly associated with reduced malaria prevalence irrespective of resistance