Populations In West Africa Research Articles

Normal values of proximal aorta diameters in healthy Sub Saharan Africans: The TAHES study.

Reported ranges of normal values are mostly issued from studies performed with Caucasians. This study is a part of TAHES, a population-based prospective cohort study in Benin and aims to establish normal reference values for echocardiographic diameters of the proximal aorta in Africans. Transthoracic echocardiography (TTE) examinations were performed by four cardiologists following pre-defined protocols, and analyzed off-line by a single observer. Aortic root diameters were measured during diastole for sinuses of Vasalva (SV), sinotubular junction (STJ) and proximal ascending aorta (AA), and during systole for annulus. Upper limits were defined as the 95th percentiles. We included 513 normotensive, non-diabetic, and cardiovascular disease-free individuals (206 men, 307 women, age 40±14 years). The diameters of the proximal aorta were significantly greater in men. The inner-edge-to-inner-edge non-indexed upper values for the annulus, SV, STJ and AA were respectively 25, 34, 28.5, 32mm in men and 22, 30, 26, 30mm in women. The leading-edge-to-leading-edge upper values were respectively 38, 35, 36 for men and 34, 33, 32mm for women. No significant differences between sexes were recorded for body surface area (BSA)-indexed diameters of the annulus, STJ and AA. BSA-indexed SV dimension was greater in men than women were. SV, STJ, AA indexed-diameters correlated with age in both sexes but not for annulus indexed-diameter. Normal values from a general population in West Africa could to differ from those established in Caucasian populations. Ethnic-specific reference diameters are here proposed for appropriate diagnosis of proximal aortic diseases in sub-Saharan Africa.

Normal values of aortic root diameters in sub-Saharan Africans: The TAHES study

Reported ranges of normal values are mostly issued from Caucasian cohorts. Data on black African subjects are sparse and not issued from community-dwelling cohorts. Our study aimed to establish reference values for ARD in a Beninese general population cohort. This study is a part of TAHES, a population-based prospective cohort study initiated in 2015 in the district of Tanvè, Republic of Benin. Transthoracic echocardiography examinations were performed by 4 cardiologists, and analyzed off-line by a single observer. ARD were measured using inner-edge to inner-edge diameters for sinuses of Vasalva (SV), sinotubular junction (STJ), proximal ascending aorta (AA), and annulus. Normal limits were defined as the 95th percentiles. Variables are presented as mean ± SD (5th–95th percentiles). We included 513 normotensive individuals (206 men and 307 women, age 40 ± 14 years [26–68]). The absolute values of ARD were significantly greater in men: the non-indexed ARD values for the annulus, SV, STJ and AA were respectively 21.3 ± 2 (18.5–25), 28.5 ± 3.4 (23–34), 24.1 ± 3 (19–29) and 27 ± 3 (22.5–32) mm for men and 19.3 ± 1.8 (15–22), 25.8 ± 2.8 (21.6–30), 22 ± 2.7 (18–26) and 24.8 ± 2.8 (21–30) mm for women, respectively (all P < 0.0001). No significant differences between sexes were recorded for body surface area (BSA)-indexed ARD for Annulus, STJ and AA. BSA-indexed SV dimension was greater in men (17.3 ± 2.6 mm; 13.5–22) than women (16.8 ± 2.5 mm; 13–21). There was a correlation between SV, STJ, AA indexed-diameters and age in both sexes but not for annulus indexed-diameter ( r = 0.14, 0.19 and 0.36 for women and 0.34, 0.45 and 0.32 for men, all P < 0.05). The upper limits for ARD are summarized in Table 1 . Normal values from a general population in West Africa could to differ from those established in Caucasian populations. This ethnic-appropriate reference is proposed for appropriate diagnosis in patients in sub-Saharan Africa.

Changement climatique et réfugiés en Afrique de l’Ouest (1990-2020)

Climate change is already forcing people to flee their lands, their homes and putting many others at risk of future displacement. In 1990, 2.3 million people were displaced due to climate change in Africa (OXFAM, 2017). Climate change is forcing people to leave their places of residence. Therefore, what were the effects of climate change on the displacement of populations in West Africa from 1990 to 2020? The objective of this study is to analyze the effects of climate change on the displacement of populations in West Africa. This study will draw on sources from IOM, IDMC, AU, ECOWAS, AFDB, UNESCO, UNEP, OXFAM and USAID. It will also build on other previous and recent work that addresses the issue of climate refugees in West Africa. The cross-referencing of these different documents will allow us to identify our different areas of interest. Thus, this study shows that climate change is both an amplifier and an intensifier of the phenomenon of climate refugees. Furthermore, most authors agree that climate change is not the only factor underlying the refugee phenomenon.

Molecular Detection and Characterization of Intestinal and Blood Parasites in Wild Chimpanzees (Pan troglodytes verus) in Senegal.

Simple SummaryWestern chimpanzees are currently listed as a Critically Endangered subspecies. Human encroachment has taken a toll on this great ape due to fragmented habitat and the exchange of pathogens. This epidemiological study investigated the occurrence and genetic diversity of intestinal and blood parasites in faecal samples from wild chimpanzees living in the Dindefelo Community Nature Reserve, Senegal. We paid special attention to potential human-driven sources of infection and transmission pathways. Potential diarrhoea-causing protist parasites (e.g., Cryptosporidium spp., Giardia duodenalis, Entamoeba histolytica) were detected at low infection rates (and densities) or absent, whereas commensals (Entamoeba dispar) or protist of uncertain pathogenicity (Blastocystis sp.) were far more abundant. We detected Sarcocystis spp. in chimpanzee faeces. Blood protist parasites such as Plasmodium spp. and Trypanosoma brucei spp. (the etiological agents of malaria and sleeping sickness, respectively, in humans) were also found at low prevalences, but microfilariae of the nematode Mansonella perstans were frequently found. Molecular analyses primarily revealed host-adapted species/genotypes and an apparent absence of gastrointestinal clinical manifestations in infected chimpanzees. Zoonotic events of still unknown frequency and directionality may have taken part between wild chimpanzees and humans sharing natural habitats and resources.Wild chimpanzee populations in West Africa (Pan troglodytes verus) have dramatically decreased as a direct consequence of anthropogenic activities and infectious diseases. Little information is currently available on the epidemiology, pathogenic significance, and zoonotic potential of protist species in wild chimpanzees. This study investigates the occurrence and genetic diversity of intestinal and blood protists as well as filariae in faecal samples (n = 234) from wild chimpanzees in the Dindefelo Community Nature Reserve, Senegal. PCR-based results revealed the presence of intestinal potential pathogens (Sarcocystis spp.: 11.5%; Giardia duodenalis: 2.1%; Cryptosporidium hominis: 0.9%), protist of uncertain pathogenicity (Blastocystis sp.: 5.6%), and commensal species (Entamoeba dispar: 18.4%; Troglodytella abrassarti: 5.6%). Entamoeba histolytica, Enterocytozoon bieneusi, and Balantioides coli were undetected. Blood protists including Plasmodium malariae (0.4%), Trypanosoma brucei (1.3%), and Mansonella perstans (9.8%) were also identified. Sanger sequencing analyses revealed host-adapted genetic variants within Blastocystis, but other parasitic pathogens (C. hominis, P. malariae, T. brucei, M. perstans) have zoonotic potential, suggesting that cross-species transmission between wild chimpanzees and humans is possible in areas where both species overlap. Additionally, we explored potential interactions between intestinal/blood protist species and seasonality and climate variables. Chimpanzees seem to play a more complex role on the epidemiology of pathogenic and commensal protist and nematode species than initially anticipated.

Normal values of aortic root diameters in sub saharan africans: the TAHES study

Abstract Introduction Reference values of aortic root diameters (ARD) are proposed to define normal versus diseased aorta. However, reported ranges of normal values are mostly issued from Caucasian cohorts. Data on blacks African subjects are sparse and not issued from community-dwelling cohorts. Purpose Our study aimed to establish reference values for ARD in a Beninese general population cohort. Methods This study is a part of TAHES, a population-based prospective cohort study initiated in 2015 in the district of Tanvè, Republic of Benin. Demographic, blood pressure and blood glucose data were collected using a questionnaire adapted from WHO-STEPS tools. Transthoracic echocardiography examinations were performed by 4 cardiologists, and analyzed off-line by a single observer. ARD were measured using inner-edge to inner-edge diameters during diastole for sinuses of Vasalva (SV), sinotubular junction (STJ) and proximal ascending aorta (AA), and during systole for annulus. Normal limits were defined as the 95th percentiles. Variables are presented as mean ±SD (5th-95th percentiles). Results We included 513 normotensive, non-diabetic and cardiovascular disease-free individuals (206 men and 307 women, age 40±14 years [26–68]). The absolute values of ARD were significantly greater in men: the non-indexed ARD values for the annulus, SV, STJ and AA were respectively 21.3±2 (18.5–25), 28.5±3.4 (23–34), 24.1±3 (19–29) and 27±3 (22.5–32) mm for men and 19.3±1.8 (1.8 (15- 22), 25.8±2.8 (21.6–30), 22±2.7 (18–26) and 24.8±2.8 (21–30) mm for women, respectively (all p&amp;lt;0.0001). No significant differences between sexes were recorded for body surface area (BSA)-indexed ARD for Annulus, STJ and AA. BSA-indexed SV dimension was greater in men (17.3±2.6 mm; 13.5–22) than women (16.8±2.5 mm; 13–21). There was a correlation between SV, STJ, AA indexed-diameters and age in both sexes but not for annulus indexed-diameter (r=0.14, 0.19 and 0.36 for women and 0.34, 0.45 and 0.32 for men, all p&amp;lt;0.05). The upper limits for ARD are summarized in Table 1. In order to compare these values to those in Caucasians, the data of the NORRE study are also displayed. Conclusion Normal values from a general population in West Africa appear could to differ from those established in Caucasian populations. This ethnic-appropriate reference is proposed for appropriate diagnosis in patients in sub-Saharan Africa. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): APREL (CHU Limoges) Table 1

The nature and extent of demographic dividend in West Africa: National transfer account approach

The population of West Africa is fast growing with a projection of large youth population which may limit the potential opportunity provided by the African Agenda 2063 and the global 2030 Agenda for Sustainable Development of the sub-region. This study investigates the nature and extent of demographic dividend in the West African sub-region, using the National Transfer Accounts (NTA) methodology. The Countries in the sub-region were aggregated based on the two available monetary zones including West Africa Monetary Zone (WAMZ) and West African Economic and Monetary Union (UEMOA). Findings reveal that children consumption is lower than for adults in West Africa. However, consumption expenditure is lower in the UEMOA countries, than in WAMZ or the West African average at all age groups. It is also found that UEMOA countries reached peak income earlier than those of WAMZ. In addition, consumption expenditure exceeds the labour income at all ages below 29 years while surplus ends at 63 years. The study further discovered that West Africa had entered the period of first demographic dividend since year 1999, and expected to peak in the year 2049.

Thiamine deficiency in Gambian women of reproductive age.

Thiamine deficiency disorders are associated with a variety of clinical symptoms affecting the nervous and cardiovascular systems. There is growing recognition that thiamine deficiency can occur in populations well beyond the classical region of South Asia, and at‐risk populations include those who receive a large proportion of their energy from polished white rice (or other low‐thiamine staple foods) and with low dietary diversity. Reports of thiamine deficiency in West Africa over the last century have suggested that this has historically been an issue in this population, but in more recent decades, these reports have been limited to prison populations. To understand if thiamine deficiency might be an unrecognized problem in the communities of this region, erythrocyte samples collected during the wet and dry seasons from 226 women of reproductive age (mean age = 28 years old) were assessed for thiamine status by measuring the erythrocyte transketolase activity coefficient (ETKac). Overall, 35.8% of the sample was at high risk of thiamine deficiency (ETKac ≥ 1.25). Risk of thiamine deficiency was significantly higher in the wet (47.9%) compared with the dry season (22.9%) (P < 0.001). To our knowledge, this is the first report of biochemical thiamine deficiency in a free‐living population in West Africa in the 21st century and suggests that further investigation is warranted.

Reported health and social consequences of the COVID-19 pandemic on vulnerable populations and implemented solutions in six West African countries: A media content analysis.

Coronavirus has spread worldwide with over 140 million cases and resulting in more than 3 million deaths between November 2019 to April 2021, threatening the socio-economic and psychosocial stability of many families and communities. There has been limited research to understand the consequences of COVID-19 on vulnerable populations in West Africa, and whether such consequences differ by countries’ previous experience with Ebola. Using a media analysis of leading online news sources, this study identified the populations particularly vulnerable to the threats of the COVID-19 pandemic, described the consequences of COVID-19 experienced by these populations, and reported on the solutions to address them. All articles from the selected news sources published between January 1 and June 30, 2020 on 6 West African countries were imported into Dedoose. A total of 4,388 news articles were coded for excerpts on vulnerable populations, only 285 excerpts of which mentioned the existing effects of COVID-19 on vulnerable populations or implemented solutions. News articles from countries with past experience with Ebola were more likely to mention the pandemic’s effects on vulnerable populations, especially on incarcerated people. Vulnerable groups were reported to have experienced a range of effects including economic disruptions, heightened domestic and sexual abuse, arbitrary arrests, health care inaccessibility, and educational challenges throughout the pandemic. With implications for the achievement of the Sustainable Development Goals (SDG) for 2030 in West Africa, these countries should consider and focus more strategic efforts on vulnerable populations to overcome their fight against the COVID-19 pandemic and to achieve the SDG for 2030.

Feasibility Study of the "HemoTypeSC" Test for the Rapid Screening of Sickle Cell Disease in Côte D'Ivoire.

Sickle cell disease is a hereditary disease that predominantly affects black people. It is very widespread in sub-Saharan Africa, particularly at the Lehmann “sickle belt” level, where the prevalence of the hemoglobin S involves at least 10% of the population in West Africa and can reach 40% in Central Africa. In Côte d'Ivoire, the prevalence of the hemoglobin S is about 12–14% in the general population and about 11.71% in the child population in Abidjan. On the other hand, its coexistence with other hemoglobin phenotypes such as AC (6.2%) and β-thalassemia (2.7%) traits may also cause composite heterogeneous sickle cell disease, e.g., SC or S/β-thalassemia in this study. Since 2009, sickle cell disease has been recognized as a public health problem; however, much still remains to be performed despite the progress achieved. The objective of this study is thus to promote a rapid screening for the struggling against sickle cell disease in Côte d'Ivoire. This study was carried out over 6 months (April–September 2019) and has included 336 children, of which 236 all-comers, recruited in the municipality of Treichville in Abidjan and 100 other children with already known hemoglobin phenotype followed up in the Hematology Department of the University Hospital of Treichville. Two tests were used: the HemoTypeSC™ for rapid screening and the hemoglobin electrophoresis which is the reference method used for confirming the diagnosis in the laboratory. The findings confirmed the reliability of the HemoTypeSC™ with a sensitivity and specificity at 100% for the detection of hemoglobin A, S, and C. On the other hand, this sensitivity and specificity drop to 98.2% and 99.7%, respectively, when we analyze all the 336 children together, including the cases with HbF detected by hemoglobin electrophoresis. Hence, the importance of performing certainty tests following the HemoTypeSC™ screening test in order to determine the accurate phenotypes and proportions of the types of hemoglobin. The prevalence of hemoglobin S in subgroup 1 of 236 children of all-comers was 15%. The HemoTypeSC™ is therefore reliable, inexpensive, and disposable for rapid screening and early detection of sickle cell disease in Côte d'Ivoire. The HemoTypeSC™ provides rapid detection of hemoglobin phenotypes HbAA, HbSS, HbSC, HbCC, HbAS, and HbAC.

Mathematical modelling and control of African animal trypanosomosis with interacting populations in West Africa-Could biting flies be important in main taining the disease endemicity?

African animal trypanosomosis (AAT) is transmitted cyclically by tsetse flies and mechanically by biting flies (tabanids and stomoxyines) in West Africa. AAT caused by Trypanosoma congolense, T. vivax and T. brucei brucei is a major threat to the cattle industry. A mathematical model involving three vertebrate hosts (cattle, small ruminants and wildlife) and three vector flies (Tsetse flies, tabanids and stomoxyines) was described to identify elimination strategies. The basic reproduction number (R0) was obtained with respect to the growth rate of infected wildlife (reservoir hosts) present around the susceptible population using a next generation matrix technique. With the aid of suitable Lyapunov functions, stability analyses of disease-free and endemic equilibria were established. Simulation of the predictive model was presented by solving the system of ordinary differential equations to explore the behaviour of the model. An operational area in southwest Nigeria was simulated using generated pertinent data. The R0 < 1 in the formulated model indicates the elimination of AAT. The comprehensive use of insecticide treated targets and insecticide treated cattle (ITT/ITC) affected the feeding tsetse and other biting flies resulting in R0 < 1. The insecticide type, application timing and method, expertise and environmental conditions could affect the model stability. In areas with abundant biting flies and no tsetse flies, T. vivax showed R0 > 1 when infected wildlife hosts were present. High tsetse populations revealed R0 <1 for T. vivax when ITT and ITC were administered, either individually or together. Elimination of the transmitting vectors of AAT could cost a total of US$ 1,056,990 in southwest Nigeria. Hence, AAT in West Africa can only be controlled by strategically applying insecticides targeting all transmitting vectors, appropriate use of trypanocides, and institutionalising an appropriate barrier between the domestic and sylvatic areas.

Ivory Coast without ivory: Massive extinction of African forest elephants in Côte d'Ivoire.

In pre-colonial and colonial times Côte d'Ivoire probably hosted one of the largest elephant populations in West Africa, resulting in the country's name Côte d'Ivoire (in English Ivory Coast) by French settlers. Numbers declined and by the early 90s it was estimated that the total number of both savannah and forest elephants had reached 63 to 360 elephants in the entire country. Here we present updated information on the distribution and conservation status of forest elephant in Côte d'Ivoire based on multiple sources-dung counts on line transects, records of human-elephant conflict, media reports, sign and interview surveys-obtained during the period 2011-2017. We used Pearson correlation to determine the correlation between the presence of forest elephant and site variables (size of the forest, percentage of area converted into plantation, size of the forest left, size of human population inside the PA, poaching index, distance to the nearest road, population density in the Department, level of protection of the PA). To examine the effect of ecological traits on elephant extirpation, we used Principal Components Analysis (PCA) to check for multicollinearity among variables. Based on dung count elephant presence was confirmed in only 4 of the 25 protected areas surveyed. PAs with higher level of protection have higher probability to be home of elephant population. The viability of these populations is uncertain, since they have a small size and are isolated. Aggressive conservation actions including law enforcement for the protection of their remaining habitat and ranger patrolling are needed to protect the remaining forest elephant populations.

Spreading of SARS-CoV-2 in West Africa and assessment of risk factors.

Although the African continent is, for the moment, less impacted than the rest of the world, it still faces the risk of a spread of COVID-19. In this study, we have conducted a systematic review of the information available in the literature in order to provide an overview of the epidemiological and clinical features of COVID-19 pandemic in West Africa and of the impact of risk factors such as comorbidities, climatic conditions and demography on the pandemic. Burkina Faso is used as a case study to better describe the situation in West Africa. The epidemiological situation of COVID-19 in West Africa is marked by a continuous increase in the numbers of confirmed cases. This geographic area had on 29 July 2020, 131 049 confirmed cases by polymerase chain reaction, 88 305 recoveries and 2102 deaths. Several factors may influence the SARS-CoV-2 circulation in Africa: (i) comorbidities: diabetes mellitus and high blood pressure could lead to an increase in the number of severe cases of SARS-CoV-2; (ii) climatic factors: the high temperatures could be a factor contributing to slow the spread of the virus and (iii) demography: the West Africa population is very young and this could be a factor limiting the occurrence of severe forms of SARS-CoV-2 infection. Although the spread of the SARS-CoV-2 epidemic in West Africa is relatively slow compared to European countries, vigilance must remain. Difficulties in access to diagnostic tests, lack of hospital equipment, but also the large number of people working in the informal sector (such as trading, businesses, transport and restoration) makes it difficult to apply preventive measures, namely physical distancing and containment.

Disentangling basal and accrued height-for-age for cross-population comparisons.

Current standards for comparing stunting across human populations assume a universal model of child growth. Such comparisons ignore population differences that are independent of deprivation and health outcomes. This article partitions variation in height-for-age that is specifically associated with deprivation and health outcomes to provide a basis for cross-population comparisons. Using a multilevel model with a sigmoid relationship of resources and growth, we partition variation in height-for-age z-scores (HAZ) from 1.5 million children across 70 countries into two components: (1) "accrued HAZ" shaped by environmental inputs (e.g., undernutrition, infectious disease, inadequate sanitation, poverty) and (2) a country-specific "basal HAZ" independent of such inputs. We validate these components against population-level infant mortality rates and assess how these basal differences may affect cross-population comparisons of stunting. Basal HAZ differs reliably across countries (range of approximately 1.5 SD) and is independent of measures of infant mortality. By contrast, accrued HAZ captures stunting as impaired growth due to deprivation and is more closely associated with infant mortality than observed HAZ. Assessing stunting prevalence by accrued HAZ suggest that populations in West Africa and Haiti suffer much greater levels of stunting than indicated by observed HAZ. Current universal standards may dramatically underestimate stunting in populations with taller basal HAZ. Relying on observed HAZ rather than accrued HAZ may also lead to inappropriate cross-population comparisons, such as concluding that Haitian children enjoy better conditions for growth than do Indian or Guatemalan children.

Influence of genetic polymorphism on transcriptional enhancer activity in the malaria vector Anopheles coluzzii

Enhancers are cis-regulatory elements that control most of the developmental and spatial gene expression in eukaryotes. Genetic variation of enhancer sequences is known to influence phenotypes, but the effect of enhancer variation upon enhancer functional activity and downstream phenotypes has barely been examined in any species. In the African malaria vector, Anopheles coluzzii, we identified candidate enhancers in the proximity of genes relevant for immunity, insecticide resistance, and development. The candidate enhancers were functionally validated using luciferase reporter assays, and their activity was found to be essentially independent of their physical orientation, a typical property of enhancers. All of the enhancers segregated genetically polymorphic alleles, which displayed significantly different levels of functional activity. Deletion mutagenesis and functional testing revealed a fine structure of positive and negative regulatory elements that modulate activity of the enhancer core. Enhancer polymorphisms segregate in wild A. coluzzii populations in West Africa. Thus, enhancer variants that modify target gene expression leading to likely phenotypic consequences are frequent in nature. These results demonstrate the existence of naturally polymorphic A. coluzzii enhancers, which may help explain important differences between individuals or populations for malaria transmission efficiency and vector adaptation to the environment.

Health Protection in Ghana and Senegal: What is the ILO’s Role?

In West Africa, the right of access to universal social security is far from being respected. International institutions and African governments have been mobilising for several years to fight this phenomenon. In a role that has evolved over the years, the International Labour Organization (ILO) provides technical and financial support to countries in this regard. How and why does the ILO intervene in protecting the health of populations in West Africa? For this institutional study, the methodology is based on a literature review focused on the history of the role of the ILO in the protection of healthcare in West Africa, specifically in Ghana and Senegal. We show the ILO’s involvement since the 1990s for two main reasons: firstly, the lack of access to healthcare in countries with a specific labour form; secondly, the rejection of the idea of social protection by dominant players on the international scene, leading to criticism following the structural adjustment programmes. In the contexts of Ghana and Senegal, both of which have experienced transitions from community-based health mechanisms to universal health coverage, we explain that the ILO has several ways to intervene—technically, institutionally, and financially. An important outcome is the revelation that the vision of the ILO with regard to health protection is systemic, articulating alternative ways to address social protection for the informal economy compared to other international organisations. But this approach is understated considering the dire situation in Africa and the need to improve access to healthcare and progress towards the Sustainable Development Goals.

The complex geography of domestication of the African rice Oryza glaberrima.

While the domestication history of Asian rice has been extensively studied, details of the evolution of African rice remain elusive. The inner Niger delta has been suggested as the center of origin but molecular data to support this hypothesis is lacking. Here, we present a comprehensive analysis of the evolutionary and domestication history of African rice. By analyzing whole genome re-sequencing data from 282 individuals of domesticated African rice Oryza glaberrima and its progenitor O. barthii, we hypothesize a non-centric (i.e. multiregional) domestication origin for African rice. Our analyses showed genetic structure within O. glaberrima that has a geographical association. Furthermore, we have evidence that the previously hypothesized O. barthii progenitor populations in West Africa have evolutionary signatures similar to domesticated rice and carried causal domestication mutations, suggesting those progenitors were either mislabeled or may actually represent feral wild-domesticated hybrids. Phylogeographic analysis of genes involved in the core domestication process suggests that the origins of causal domestication mutations could be traced to wild progenitors in multiple different locations in West and Central Africa. In addition, measurements of panicle threshability, a key early domestication trait for seed shattering, were consistent with the gene phylogeographic results. We suggest seed non-shattering was selected from multiple genotypes, possibly arising from different geographical regions. Based on our evidence, O. glaberrima was not domesticated from a single centric location but was a result of diffuse process where multiple regions contributed key alleles for different domestication traits.

Measurements of nitric oxide and ammonia soil fluxes from a wet savanna ecosystem site in West Africa during the DACCIWA field campaign

Abstract. Biogenic fluxes from soil at a local and regional scale are crucial to study air pollution and climate. Here we present field measurements of soil fluxes of nitric oxide (NO) and ammonia (NH3) observed over four different land cover types, i.e. bare soil, grassland, maize field, and forest, at an inland rural site in Benin, West Africa, during the DACCIWA field campaign in June and July 2016. At the regional scale, urbanization and a massive growth in population in West Africa have been causing a strong increase in anthropogenic emissions. Anthropogenic pollutants are transported inland and northward from the megacities located on the coast, where the reaction with biogenic emissions may lead to enhanced ozone production outside urban areas, as well as secondary organic aerosol formation, with detrimental effects on humans, animals, natural vegetation, and crops. We observe NO fluxes up to 48.05 ngN m−2 s−1. NO fluxes averaged over all land cover types are 4.79±5.59 ngN m−2 s−1, and maximum soil emissions of NO are recorded over bare soil. NH3 is dominated by deposition for all land cover types. NH3 fluxes range between −6.59 and 4.96 ngN m−2 s−1. NH3 fluxes averaged over all land cover types are -0.91±1.27 ngN m−2 s−1, and maximum NH3 deposition is measured over bare soil. The observations show high spatial variability even for the same soil type, same day, and same meteorological conditions. We compare point daytime average measurements of NO emissions recorded during the field campaign with those simulated by GEOS-Chem (Goddard Earth Observing System Chemistry Model) for the same site and find good agreement. In an attempt to quantify NO emissions at the regional and national scale, we also provide a tentative estimate of total NO emissions for the entire country of Benin for the month of July using two distinct methods: upscaling point measurements and using the GEOS-Chem model. The two methods give similar results: 1.17±0.6 and 1.44 GgN month−1, respectively. Total NH3 deposition estimated by upscaling point measurements for the month of July is 0.21 GgN month−1.

Climate change resilience of a globally important sea turtle nesting population.

Few studies have looked into climate change resilience of populations of wild animals. We use a model higher vertebrate, the green sea turtle, as its life history is fundamentally affected by climatic conditions, including temperature-dependent sex determination and obligate use of beaches subject to sea level rise (SLR). We use empirical data from a globally important population in West Africa to assess resistance to climate change within a quantitative framework. We project 200years of primary sex ratios (1900-2100) and create a digital elevation model of the nesting beach to estimate impacts of projected SLR. Primary sex ratio is currently almost balanced, with 52% of hatchlings produced being female. Under IPCC models, we predict: (a) an increase in the proportion of females by 2100 to 76%-93%, but cooler temperatures, both at the end of the nesting season and in shaded areas, will guarantee male hatchling production; (b) IPCC SLR scenarios will lead to 33.4%-43.0% loss of the current nesting area; (c) climate change will contribute to population growth through population feminization, with 32%-64% more nesting females expected by 2120; (d) as incubation temperatures approach lethal levels, however, the population will cease growing and start to decline. Taken together with other factors (degree of foraging plasticity, rookery size and trajectory, and prevailing threats), this nesting population should resist climate change until 2100, and the availability of spatial and temporal microrefugia indicates potential for resilience to predicted impacts, through the evolution of nest site selection or changes in nesting phenology. This represents the most comprehensive assessment to date of climate change resilience of a marine reptile using the most up-to-date IPCC models, appraising the impacts of temperature and SLR, integrated with additional ecological and demographic parameters. We suggest this as a framework for other populations, species and taxa.

Potential of Deficit and Supplemental Irrigation under Climate Variability in Northern Togo, West Africa

In the context of a growing population in West Africa and frequent yield losses due to erratic rainfall, it is necessary to improve stability and productivity of agricultural production systems, e.g., by introducing and assessing the potential of alternative irrigation strategies which may be applicable in this region. For this purpose, five irrigation management strategies, ranging from no irrigation (NI) to controlled deficit irrigation (CDI) and full irrigation (FI), were evaluated concerning their impact on the inter-seasonal variability of the expected yields and improvements of the yield potential. The study was conducted on a maize crop (Zea mays L.) at a representative site in northern Togo with a hot semi-arid climate and pronounced dry and wet rainfall seasons. The OCCASION (Optimal Climate Change Adaption Strategies in Irrigation) framework was adapted and applied. It consists of: (i) a weather generator for simulating long climate time series; (ii) the AquaCrop model, which was used to simulate the irrigation system during the growing season and the yield response of maize to the considered irrigation management strategies; and (iii) a problem-specific algorithm for optimal irrigation scheduling with limited water supply. We found high variability in rainfall during the wet season which leads to considerable variability in the expected yield for rainfed conditions (NI). This variability was significantly reduced when supplemental irrigation management strategies (CDI or FI) requiring a reasonably low water demand of about 150 mm were introduced. For the dry season, it was shown that both irrigation management strategies (CDI and FI) would increase yield potential for the local variety TZEE-W up to 4.84 Mg/ha and decrease the variability of the expected yield at the same time. However, even with CDI management, more than 400 mm of water is required if irrigation would be introduced during the dry season in northern Togo. Substantial rainwater harvesting and irrigation infrastructures would be needed to achieve that.

Novel Wolbachia strains in Anopheles malaria vectors from Sub-Saharan Africa.

Background: Wolbachia, a common insect endosymbiotic bacterium that can influence pathogen transmission and manipulate host reproduction, has historically been considered absent from the Anopheles (An.)genera, but has recently been found in An. gambiaes.l. populations in West Africa. As there are numerous Anophelesspecies that have the capacity to transmit malaria, we analysed a range of species across five malaria endemic countries to determine Wolbachiaprevalence rates, characterise novel Wolbachiastrains and determine any correlation between the presence of Plasmodium, Wolbachiaand the competing bacterium Asaia. Methods: Anophelesadult mosquitoes were collected from five malaria-endemic countries: Guinea, Democratic Republic of the Congo (DRC), Ghana, Uganda and Madagascar, between 2013 and 2017. Molecular analysis was undertaken using quantitative PCR, Sanger sequencing, Wolbachiamultilocus sequence typing (MLST) and high-throughput amplicon sequencing of the bacterial 16S rRNAgene. Results: Novel Wolbachiastrains were discovered in five species: An. coluzzii, An. gambiaes.s., An. arabiensis, An. mouchetiand An.species A, increasing the number of Anophelesspecies known to be naturally infected. Variable prevalence rates in different locations were observed and novel strains were phylogenetically diverse, clustering with Wolbachiasupergroup B strains. We also provide evidence for resident strain variants within An. species A. Wolbachiais the dominant member of the microbiome in An. mouchetiand An.species A but present at lower densities in An. coluzzii. Interestingly, no evidence of Wolbachia/Asaiaco-infections was seen and Asaiainfection densities were shown to be variable and location dependent. Conclusions:The important discovery of novel Wolbachiastrains in Anophelesprovides greater insight into the prevalence of resident Wolbachiastrains in diverse malaria vectors. Novel Wolbachiastrains (particularly high-density strains) are ideal candidate strains for transinfection to create stable infections in other Anophelesmosquito species, which could be used for population replacement or suppression control strategies.