Malaria infection and disease in an area with pyrethroid-resistant vectors in southern Benin

<p>Abstract</p> <p>Background</p> <p>This study aimed to investigate baseline data on malaria before the evaluation of new vector control strategies in an area of pyrethroid-resistance of vectors. The burden of malaria was estimated in terms of infection (prevalence and parasite density) and of clinical episodes.</p> <p>Methods</p> <p>Between December 2007 and December 2008 in the health district of Ouidah - Kpomassè - Tori Bossito (southern Benin), a descriptive epidemiological survey of malaria was conducted. From 28 selected villages, seven were randomized from which a total of 440 children aged 0 to 5 years were randomly selected. Clinical and parasitological information was obtained by active case detection of malaria episodes carried out during eight periods of six consecutive days scheduled at six weekly intervals and by cross-sectional surveys of asymptomatic infection. Entomological information was also collected. The ownership, the use and the correct use of long-lasting insecticide-treated nets (LLINs) were checked over weekly-survey by unannounced visits at home in the late evening.</p> <p>Results</p> <p>Mean parasite density in asymptomatic children was 586 <it>P. falciparum </it>asexual forms per μL of blood (95%CI 504-680). Pyrogenic parasite cut-off was estimated 2,000 <it>P. falciparum </it>asexual blood forms per μL. The clinical incidence of malaria was 1.5 episodes per child per year (95%CI 1.2-1.9). Parasitological and clinical variables did not vary with season. <it>Anopheles gambiae </it><it>s.l</it>. was the principal vector closely followed by <it>Anopheles funestus</it>. Entomological inoculation rate was 5.3 (95%CI 1.1-25.9) infective bites per human per year. Frequency of the L1014F <it>kdr </it>(West) allele was around 50%. Annual prevalence rate of <it>Plasmodium falciparum </it>asymptomatic infection was 21.8% (95%CI 19.1-24.4) and increased according to age. Mean rates of ownership and use of LLINs were 92% and 70% respectively. The only correct use of LLINs (63%) conferred 26% individual protection against only infection (OR = 0.74 (95%IC 0.62-0.87), p = 0.005).</p> <p>Conclusion</p> <p>The health district of Ouidah-Kpomassè-Tori Bossito is a mesoendemic area with a moderate level of pyrethroid-resistance of vectors. The used LLINs rate was high and only the correct use of LLINs was found to reduce malaria infection without influencing malaria morbidity.</p

Screening of pesticide residues in soil and water samples from agricultural settings

Abstract Background The role of agricultural practices in the selection of insecticide resistance in malaria vectors has so far been hypothesized without clear evidence. Many mosquito species, Anopheles gambiae in particular, lay their eggs in breeding sites located around agricultural settings. There is a probability that, as a result of farming activities, insecticide residues may be found in soil and water, where they exercise a selection pressure on the larval stage of various populations of mosquitoes. To confirm this hypothesis, a study was conducted in the Republic of Benin to assess the environmental hazards which can be generated from massive use of pesticides in agricultural settings. Methods Lacking an HPLC machine for direct quantification of insecticide residues in samples, this investigation was performed using indirect bioassays focussed on the study of factors inhibiting the normal growth of mosquito larvae in breeding sites. The speed of development was monitored as well as the yield of rearing An. gambiae larvae in breeding sites reconstituted with water and soil samples collected in agricultural areas known to be under pesticide pressure. Two strains of An. gambiae were used in this indirect bioassay: the pyrethroid-susceptible Kisumu strain and the resistant Ladji strain. The key approach in this methodology is based on comparison of the growth of larvae in test and in control breeding sites, the test samples having been collected from two vegetable farms. Results Results obtained clearly show the presence of inhibiting factors on test samples. A normal growth of larvae was observed in control samples. In breeding sites simulated by using a few grams of soil samples from the two vegetable farms under constant insecticide treatments (test samples), a poor hatching rate of Anopheles eggs coupled with a retarded growth of larvae and a low yield of adult mosquitoes from hatched eggs, was noticed. Conclusion Toxic factors inhibiting the hatching of anopheles eggs and the growth of larvae are probably pesticide residues from agricultural practices. Samples used during this indirect assay have been stored in the laboratory and will be analysed with HPLC techniques to confirm hypothesis of this study and to identify the various end products found in soil and water samples from agricultural settings under pesticide pressure.</p

Épidémiologie de la bilharziose urinaire et des géohelminthiases chez les jeunes scolaires des zones lacustres de la commune de So-Ava, sud-Bénin

International audienceObjective: In the tropics, infections by Schistosoma haematobium and soil-transmitted helminths speciesare widespread and Republic of Benin is no exception. This study aims to assess the epidemiologicalstatus of urogenital schistosomiasis and soil-transmitted helminths in schoolchildren of Sô-Ava town in theDepartment of Atlantic in Southern Benin.Methodology and Results: The biological material was composed of urine and stool collected from fromPublic Primary Schools in Sôchanhoué, Sôtchanhoué Quarter and Sô-Zounko between April to August2012 . Six hundred and four urine samples were examined by filtration technique and 363 stool sampleswere examined by Kato-Katz test. Malacological surveys were conducted to assess the diversity offreshwater snails and determine the snail species involved in the transmission of schistosomiasis. Theresults showed infection rates of S. haematobium of 22.22% (N = 153), 21.43% (N = 182) and 46.47% (N =269) in the three prospected sites, respectively, with an overall infection rate of 32.78% (N = 604) with asmany boys as girls infected and children 7 to 8 years of age the most affected. Three species of soiltransmittedhelminths were found with an overall prevalence of 12.12% (N = 44) of people infected with atleast one of the three parasites Ascaris lumbricoides, Trichuris trichiura or Enterobius vermicularis. Theresults showed that the parasite densities of S. haematobium and soil-transmitted helminths were thegreatest in children aged 7 to 8 years, especially boys. Three species of freshwater snails known asintermediate hosts for schistosomes were collected: Bulinus forskalii, B. globosus and B. truncatus.Conclusion: This study was used to assess the level of endemicity of urinary schistosomiasis and soiltransmittedhelminths in human populations of the Nokoue Lake area and allows considering theappropriate means of controlling these parasites.Objectif : Dans les zones intertropicales, les infestations par Schistosoma haematobium et autres espècesd’helminthes sont très répandues et le Bénin ne fait pas exception. Cette étude a pour objectif d’évaluer lestatut épidémiologique de la Bilharziose urogénitale et des géohelminthiases chez les enfants d’âgescolaire de la commune de Sô-Ava, Département de l’Atlantique dans le Sud-Bénin.Méthodologie et Résultats : Le matériel biologique est composé d'urines et de selles provenant de jeunesécoliers âgés de 4 à 8 ans et scolarisés dans les Ecoles Primaires Publiques de Sô-Tchanhoué village, Sô-Tchanhoué Quartier et de Sô-Zounko de la commune de Sô-Ava. Les trois sites de prospection font partiede la commune de Sô-Ava. Six cent quatre échantillons d'urine ont été examinés par la technique defiltration et 363 échantillons de selles examinées par la technique de Kato-Katz. Les résultats d'analyse desurines révèlent les prévalences respectives à S. haematobium de 22,22% (N=153) ; 21,43% (N=182) et46,47% (N=269) dans les trois villages pour une prévalence globale de 32,78% (N= 604) avec autant degarçons que de filles infestés et les enfants de 7 à 8 ans constituent la tranche d’âge la plus touchée. Lesrésultats d'analyse des selles révèlent trois espèces d'helminthes avec une prévalence globale de 12,12%(N=44) de personnes infestées par au moins un des trois parasites Ascaris lumbricoides, Trichuris trichiuraet Enterobius vermicularis. Aucun oeuf de S. mansoni n’a été observé dans les selles. Les résultatsmontrent enfin que les charges parasitaires de S. haematobium et des géohelminthes étaient plusimportantes chez les enfants de 7 à 8 ans, en particulier chez les garçons. Les prospections malacologiques ont été réalisées afin d’évaluer la diversité malacologique et déterminer les mollusquesimpliqués dans la transmission des schistosomes. Trois espèces de mollusques connues comme hôtesintermédiaires de schistosomes ont été collectées Bulinus forskalii, B. globosus et B. truncatus.Conclusion : Cette étude a permis d’évaluer le niveau d’endémicité de la bilharziose urogénitale et desgéohelminthes au niveau des populations humaines de cette zone lacustre et permet d’envisager lesmoyens adéquats pour le contrôle de ces parasitose

Prevalence of nosocomial infections and anti-infective therapy in Benin: results of the first nationwide survey in 2012

Data on nosocomial infections in hospitals in low-income countries are scarce and often inconsistent. The objectives of this study were to estimate the prevalence of nosocomial infections and antimicrobial drug use in Benin hospitals

Seroepidemiology of toxoplasmosis in pregnant women and detection of infection acquired during pregnancy in Cotonou, Benin

Assessing the prevalence of toxoplasmosis in pregnant women and the associated risk factors is the first step in defining policy for the prevention of congenital toxoplasmosis in a given population. An epidemiological study was conducted during prenatal consultations at the CHU-MEL of Cotonou (Benin) between September 2018 and April 2021 and recruited 549 pregnant women to determine the seroprevalence and potential factors associated with Toxoplasma gondii infection. Toxoplasma gondii IgG/IgM antibodies were detected using an enzyme-linked fluorescence assay (ELFA) technique, an IgG avidity test and an IgG/IgM comparative Western blot to diagnose the maternal toxoplasmosis serological status, the possibility of an infection acquired during pregnancy and congenital infection, respectively. Concomitantly, the participants answered a questionnaire investigating potential risk factors. Toxoplasmosis seroprevalence was estimated at 44.4% (95% CI 40.3–48.6) and the factors significantly associated with T. gondii seropositivity were: age over 30 years, multigravid women and contact with cats. The possibility of an infection acquired during the periconceptional period or the first trimester of pregnancy concerned six women [1.1% (95% CI 0.5–2.0)]. However, due to the low rate of serological controls in seronegative women, a significant proportion of women first tested during the 3rd trimester of pregnancy, and an insufficient sample size, the incidence of primary infection during pregnancy could not be determined. No cases of congenital transmission occurred in the newborns from the suspected cases of primary infection

Cumulative STH (hookworms, Ascaris and Trichuris) prevalence and PCT strategy (n: Schoolchildren co infected by at least two STH species; schoolchildren coinfected were counted one; n1: Number of schoolchildren infected per department; PCT: Preventive chemotherapy; SAC: School age children).

<p>Cumulative STH (hookworms, Ascaris and Trichuris) prevalence and PCT strategy (n: Schoolchildren co infected by at least two STH species; schoolchildren coinfected were counted one; n1: Number of schoolchildren infected per department; PCT: Preventive chemotherapy; SAC: School age children).</p

Results of the first mapping of soil-transmitted helminths in Benin: Evidence of countrywide hookworm predominance

<div><p>Background</p><p>National mapping of soil-transmitted helminth infections (STH) was conducted for the first time in all of the 77 districts of Benin (West Africa) from 2013 to 2015. This mapping aimed to provide basic epidemiological data essential for the implementation of the national strategy against the neglected tropical diseases (NTDs) in the context of achieving the WHO target of controlling these infections by 2020.</p><p>Methods</p><p>In each district, 5 schools were purposively selected in 5 villages and 50 school-children (25 girls and 25 boys) from ages 8 to 14 years were randomly enrolled in each school. In total, 19,250 stool samples of school children (9,625 girls and 9,625 boys) from 385 schools were examined by Kato-Katz technique.</p><p>Results</p><p>The three major species of STH (hookworm, <i>Ascaris lumbricoides</i> and <i>Trichuris trichiura</i>) were observed with intra- and inter-specific variations in the prevalence and the intensity of these parasites. Hookworm infection was present in all of the surveyed districts with an average prevalence of 17.14% (95% CI 16.6%-17.6%). Among the infected schoolchildren, at national level, 90.82%, 6.73% and 2.45% of infections were of light, moderate and heavy parasite intensities respectively. A. <i>lumbricoides</i> infection, with a national average prevalence of 5.35% (95% CI 5.00%-5.60%),was the second most prevalent STH, and 84.37%, 14.27% and 1.36% of the infections were of light, moderate and heavy parasite intensities, respectively. <i>T</i>. <i>trichiura</i> had a national average prevalence of 1.15% (95% CI 0.90%-1.20%) and 80.45%, 13.18% and 6.36% infections were of light, moderate and heavy parasite intensities, respectively. The national cumulative prevalence of the three STH infections was 22.74% (95% CI 22.15%-23.33%), with58.44% (45/77) of the districts requiring mass treatment according to WHO recommendations. In all of the surveyed districts, multiple infections by STH species were common, and boys seemed more at risk of hookworm and Ascaris infections.</p><p>Conclusions</p><p>This first national mapping provided an overview of the epidemiological pattern of STH infections and was essential for the implementation of a control strategy with an effective preventive chemotherapy treatment (PCT). Results show that while preventive chemotherapy is not indicated for children in 32/77 districts, 43 require annual deworming and two require twice yearly deworming. If no environmental change occurs, and no mass treatment is delivered, prevalence is likely to remain stable for many years owing to poor hygiene and sanitation.</p></div

Prevalence (%) and intensity of <i>A</i>. <i>lumbricoides</i> infections.

<p>Prevalence (%) and intensity of <i>A</i>. <i>lumbricoides</i> infections.</p