Characterization of Ouémé River Quality in Upper Delta Using Water Evaluation Indices and Multivariate Analysis

Pollution represents a serious problem for the environment. The aim of this research was to assess the level of organic pollution of the Ouémé River and his physical quality. Nine physical and chemical parameters were measured in nine different stations between March and October 2016, during dry and rainy season. The methods used were those recommended by the French Association of Normalization (AFNOR). Data were subjected to descriptive statistical analysis and multivariate statistical technics, including principal component analysis (PCA) and variance analysis. The Leclercq Organic pollution index was used to assess the level of organic pollution. The values of the measured parameters suggest an organic pollution on all stations. The pollution degree varies according to the study area with contents that sometimes pass those recommended by the WHO standards. More advanced information about water quality for this study area were obtained. Therefore, this study will help stakeholders to better manage Ouémé River’s water

Evaluation du comportement trophique de Aedes aegypti dans la ville de cotonou au sud du Bénin

In order to evaluate the trophic behavior of Aedes aegypti in the city of Cotonou, southern Benin, a cross-sectional study was conducted in urban and periurban neighborhoods from April 2016 to August 2017 to collect Ae. Aegypti populations. To achieve this goal, day and night collections, twice a month for one year were done where Ae. Aegypti populations were caught by Human Landing Catch and BG-Sentinel traps. 3,892 Aedes caught by different methods showed that Ae. Aegypti and Ae. circumluteolus are more abundant in urban than peri-urban areas (p<0.05). The aggressive density of Ae. aegypti populations was significantly higher in urban areas (157.43 bites per man per hour) than in peri-urban areas (32.43 bites per man per hour) (p<0.05). Also, out of 250 females blood-fed Ae. Aegypti tested by ELISA (Enzyme Linked Immunosorbent Assay) technique for blood meal identification, 86.80% took their blood meal on humans compared to 4.4% which took their blood meal on sheeps. These findings showed that the city of Cotonou in southern Benin, offered good condition for the development of Ae. aegypti population. The anthropology and endophagy behavior of this mosquito observed through the results of this study is a very favorable clue to vector control strategies based on the use of long-lasting impregnated mosquito nets and insecticide residual sprays adopted in Benin

Sensibilité des populations d’ Aedes Aegypti vis-à-vis des organochlorés, pyréthrinoïdes et des carbamates dans la commune de Natitingou au Nord-Est du Bénin

Insecticide treatments for crop protection have often be cited as the main factor of the resistance selection of Aedes aegypti. This is however the main vector dengue fever. To verify this hypothesis, bioassay tests was performed on adults collected from the field (2 urban and 2 rural areas) at Natitingou to assess the susceptibility of dengue vectors to insecticideimpregnated papers (permethrin 0.75%, delthamethrin 0.05%, lambdacyalothrin 0.05%, DDT 4%, and bendiocarb 0.1%) following WHO Pesticide Evaluation Scheme. Results from this study showed that Ae. Aegypti populations were resistant to DDT and pyrethroids with 12% and 38% respectively as mean of mortality despite the areas of mosquitoes collection. However, they were fully susceptible to bendiocarb. Our study showed that Aedes aegypti populations had developed resistance to organochlorine and pyrethroids, but are susceptible to carbamate. The low mortality rate recorded in all populations of Ae. Aegypti with bendiocarb is encouraging in regards to the use of this insecticide as an alternative in case of outbreak of dengue fever in this district of Benin

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Sensibilité des Populations de Anopheles Gambiae aux Pyréthrinoïdes, Principal Vecteur du Paludisme dans la Région de Natitingou au Nord -Ouest du Bénin

Vector control programme based on deployment of insecticide treated nets (ITNs) has become the main method for malaria prevention in many endemic countries across Africa. However, the threat of pyrethroid resistance in West Africa is increasingly becoming a serious concern for the future usefulness of ITNs.Without sufficient evidence, the emergence of insecticide resistance in insect vectors has been partly attributed to the abusive use of insecticides against household and agricultural pests.To explore this hypothesis further, Knowledge Attitude-Practice (KAP) surveys were organized in the study sites (urban and rural areas) from july to October 2017. In each site, leaders of farmers organizations were interviewed using semi-structured questionnaires that focused on the treatment strategies, and the use of insecticides in the farms. Furthermore, qualitative data were collected through direct observations, in-depth interviews and focus group discussions. This was complemented by bioassay tests to assess the susceptibility of An. gambiae  to various insecticides such as deltamethrin (0.05 %), permethrin (0.75%), DDT (4%), and lambdacyhalothrine (0.05%).Results from this study showed that: i)- More than 90% of the farmers interviewed used pesticides which were not registered for pest control; ii)- most of the farmers did not respect the dose recommended for treatment; iii)- An. gambiae populations developed a high resistance against pyrethroids and organochlorine regardless the areas of collection. This study confirms once again that the use of insecticide in an improper manner to control vegetable pests in agriculture is one of the factors responsible for the selection of insecticide resistance in malaria vectors.Measure must be taken by agriculture authorities to the management of pesticides in agriculture hence reducing the selection pressure of insecticides on An. gambiae populations

Contribution de L’agriculture dans la Sélection et la Distribution de la Résistance d’Anopheles Gambiae (Diptera, Culicidae) aux Insecticides le Long du Transect Sud-Nord en République du Beninn

AbstractA study carried out along the South-North transect in Benin has shown the impacts of the use of chemical pesticides in agricultural for crop protection in the selection and spread of resistance of Anopheles gambiae s.l. to insecticidesIndeed, the knock-down resistance frequency found in An. gambiae populations from the cotton and vegetable farming fields where farmers used a high dose of chemical pesticides, is significantly higher than the one from areas with low or no use of pesticides (food crop and rice growing areas).The acetylcholinesterase mutation was also found, but only in An. gambiae populations from the areas where high dose of pesticides were used for pests controlThese findings confirm once again the role of agriculture in the selection and spread of resistance of Anopheles gambiae s.l. to insecticidesKey words: agriculture; Insecticides; Resistance; Anopheles gambiae; Benin

Baseline Entomological Indicators of Malaria Transmission Prior to the Implementation of Indoor Residual Spraying in Malanville District, Northern of Benin.

Background: To assess malaria transmission in the district of Malanville in northern Benin, an entomological study was carried out in two sites from January to December 2016.Methods: Adults mosquitoes were collected monthly by human landing catches (HLC) over two consecutive nights (8:00 PM - 6:00AM) in four compounds randomly selected from each study site. These collections were completed by indoor pyrethrum spray catches (PSC) in 10 additional compounds in each study site. The sampling method used in each compound was consistent during the study period. Head-thoraces of female mosquitoes captured by HLC were tested for the presence of circumsporozoite protein (CSP). Mosquitoes captured by PSC were preserved for species identification using polymerase chain reaction (PCR).Results: i)– Overall, 9,019 female mosquitoes were caught by PSC and 21,474 by HLC; ii) – In Malanville, Plasmodium falciparum was mainly transmitted by An. gambiae s.s where malaria transmission was high from June to November during the rainy season and declined during the dry season (December-May); iii) – The average entomological inoculation rate (EIR) was significantly higher during the rainy season(0.8 infectious bites/person/night) compared to the dry season (0.1 infectious bites/person/month) (P<0.05).Conclusion: These findings showed malaria transmission is unimodal in the city of Malanville. The main malaria parasite, Plasmodium falciparum, was transmitted by An. gambiae s.s. Results from this study will be useful for National Malaria Control Program authorities in the choice of vector control strategies to prevent malaria transmission in the district of Malanville

Genetic diversity and wing geometric morphometrics among four populations of Aedes aegypti (Diptera: Culicidae) from Benin

Abstract Background The impact of the arbovirus vector Aedes aegypti is of major concern for global public health as the viruses that it transmits affect millions of people each year worldwide. Originating in Africa, Ae. aegypti has now spread throughout much of the world. While the genetic makeup of Ae. aegypti in the New World has been extensively studied, there is limited knowledge on its genetic diversity in Africa, particularly at a microgeographical level. Methods We investigated mitochondrial cytochrome oxidase I of four Ae. aegypti populations from Benin and employed wing morphometric analyses as a cost-effective and reliable tool to explore population structure. Our sampling encompassed various areas of Benin, from the southern to the northern borders of the country, and included urban, semi-urban, and sylvatic sites. Results We observed a notable level of genetic diversity (haplotype diversity of 0.8333) and nucleotide diversity (0.00421986), and identified seven distinct haplotypes. Sylvatic and semi-urban sites exhibited a greater number of haplotypes compared to urban sites. Utilizing 18 wing landmarks, we calculated the centroid size, which revealed significant variation among the three landscape types. However, principal component analysis, employed to assess wing shape variation, did not demonstrate significant differences between populations based on landscape type. Conclusions Our findings indicate substantial genetic and morphological diversity among Ae. aegypti populations in Benin, and provide insight into important biological characteristics of these populations with respect to their potential to transmit viruses. To the best of our knowledge, this is the first study undertaken in Africa to integrate genetics with morphology to analyse the population structure of the major arbovirus vector Ae. aegypti. Graphical Abstrac

An Observational Laboratory-Based Assessment of SARS-CoV-2 Molecular Diagnostics in Benin, Western Africa

Months after the start of the COVID-19 pandemic, case numbers from Africa are surprisingly low, potentially because the number of SARS-CoV-2 tests performed in Africa is lower than in other regions. Here, we show an overload of COVID-19-related diagnostics in the central laboratory of Benin, Western Africa, with a stagnating average number of positive samples irrespective of daily sample counts