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

Plasmodium falciparum polymorphisms associated with ex vivo drug susceptibility and clinical effectiveness of artemisinin-based combination therapies in Benin

Artemisinin-based combination therapies (ACTs) are the main option to treat malaria, and their efficacy and susceptibility must be closely monitored to avoid resistance. We assessed the association of Plasmodium falciparum polymorphisms and ex vivo drug susceptibility with clinical effectiveness. Patients enrolled in an effectiveness trial comparing artemether-lumefantrine (n = 96), fixed-dose artesunate-amodiaquine (n = 96), and sulfadoxine-pyrimethamine (n = 48) for the treatment of uncomplicated malaria 2007 in Benin were assessed. pfcrt, pfmdr1, pfmrp1, pfdhfr, and pfdhps polymorphisms were analyzed pretreatment and in recurrent infections. Drug susceptibility was determined in fresh baseline isolates by Plasmodium lactate dehydrogenase enzyme-linked immunosorbent assay (ELISA). A majority had 50% inhibitory concentration (IC50) estimates (the concentration required for 50% growth inhibition) lower than those of the 3D7 reference clone for desethylamodiaquine, lumefantrine, mefloquine, and quinine and was considered to be susceptible, while dihydroartemisinin and pyrimethamine IC(50)s were higher. No association was found between susceptibility to the ACT compounds and treatment outcome. Selection was observed for the pfmdr1 N86 allele in artemether-lumefantrine recrudescences (recurring infections) (4/7 [57.1%] versus 36/195 [18.5%]), and of the opposite allele, 86Y, in artesunate-amodiaquine reinfections (new infections) (20/22 [90.9%] versus 137/195 [70.3%]) compared to baseline infections. The importance of pfmdr1 N86 in lumefantrine tolerance was emphasized by its association with elevated lumefantrine IC(50)s. Genetic linkage between N86 and Y184 was observed, which together with the low frequency of 1246Y may explain regional differences in selection of pfmdr1 loci. Selection of opposite alleles in artemether-lumefantrine and artesunate-amodiaquine recurrent infections supports the strategy of multiple first-line treatment. Surveillance based on clinical, ex vivo, molecular, and pharmacological data is warranted

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