SARS-CoV-2 infection and antibody seroprevalence in routine surveillance patients, healthcare workers and general population in Kita region, Mali: an observational study 2020–2021

Objective: To estimate the degree of SARS-CoV-2 transmission among healthcare workers (HCWs) and general population in Kita region of Mali. Design: Routine surveillance in 12 health facilities, HCWs serosurvey in five health facilities and community serosurvey in 16 villages in or near Kita town, Mali. Setting: Kita region, western Mali; local health centres around the central (regional) referral health centre. Participants: Patients in routine surveillance, HCWs in local health centres and community members of all ages in populations associated with study health centres. Main outcome measures: Seropositivity of ELISA test detecting SARS-CoV-2-specific total antibodies and real-time RT-PCR confirmed SARS-CoV-2 infection. Results: From 2392 routine surveillance samples, 68 (2.8%, 95% CI: 2.2% to 3.6%) tested positive for SARS-CoV-2 by RT-PCR. The monthly positivity rate was 0% in June–August 2020 and gradually increased to 6% by December 2020 and 6.2% by January 2021, then declined to 5.5%, 3.3%, 3.6% and 0.8% in February, March, April and May 2021, respectively. From 397 serum samples collected from 113 HCWs, 175 (44.1%, 95% CI: 39.1% to 49.1%) were positive for SARS-CoV-2 antibodies. The monthly seroprevalence was around 10% from September to November 2020 and increased to over 40% from December 2020 to May 2021. For community serosurvey in December 2020, overall seroprevalence of SARS-CoV-2 antibodies was 27.7%. The highest age-stratified seroprevalence was observed in participants aged 60–69 years (45.5%, 95% CI: 32.3% to 58.6%). The lowest was in children aged 0–9 years (14.0%, 95% CI: 7.4% to 20.6%). Conclusions: SARS-CoV-2 in rural Mali is much more widespread than assumed by national testing data and particularly in the older population and frontline HCWs. The observation is contrary to the widely expressed view, based on limited data, that COVID-19 infection rates were lower in 2020–2021 in West Africa than in other settings

On-Farm Evaluation on Yield and Economic Performance of Cereal-Cowpea Intercropping to Support the Smallholder Farming System in the Soudano-Sahelian Zone of Mali

Cereal-cowpea intercropping has become an integral part of the farming system in Mali. Still, information is lacking regarding integrated benefits of the whole system, including valuing of the biomass for facing the constraints of animal feedings. We used farmers’ learning networks to evaluate performance of intercropping systems of millet-cowpea and sorghum-cowpea in southern Mali. Our results showed that under intercropping, the grain yield obtained with the wilibali (short maturing duration) variety was significantly higher than the yield obtained with the sangaranka (long maturing duration) variety whether with millet (36%) or sorghum (48%), corresponding, respectively, to an economic gain of XOF (West African CFA franc) 125 282/ha and XOF 142 640/ha. While for biomass, the yield obtained with the sangaranka variety was significantly higher by 50% and 60% to that of wilibali with an economic gain of XOF 286 526/ha (with millet) and XOF 278 516/ha (with sorghum). Total gain obtained with the millet-cowpea system was significantly greater than that obtained with the sorghum-cowpea system by 14%, and this stands irrespective of the type of cowpea variety. Farmers prefer the grain for satisfying immediate food needs instead of economic gains. These results represent an indication for farmer’s decision-making regarding cowpea varieties selection especially for addressing household food security issues or feeding animals

Diversity, dynamics, direction, and magnitude of high-altitude migrating insects in the Sahel

This is the final version. Available from Nature Research via the DOI in this record. Long-distance migration of insects impacts food security, public health, and conservation–issues that are especially significant in Africa. Windborne migration is a key strategy enabling exploitation of ephemeral havens such as the Sahel, however, its knowledge remains sparse. In this first cross-season investigation (3 years) of the aerial fauna over Africa, we sampled insects flying 40–290 m above ground in Mali, using nets mounted on tethered helium-filled balloons. Nearly half a million insects were caught, representing at least 100 families from thirteen orders. Control nets confirmed that the insects were captured at altitude. Thirteen ecologically and phylogenetically diverse species were studied in detail. Migration of all species peaked during the wet season every year across localities, suggesting regular migrations. Species differed in flight altitude, seasonality, and associated weather conditions. All taxa exhibited frequent flights on southerly winds, accounting for the recolonization of the Sahel from southern source populations. “Return” southward movement occurred in most taxa. Estimates of the seasonal number of migrants per species crossing Mali at latitude 14°N were in the trillions, and the nightly distances traversed reached hundreds of kilometers. The magnitude and diversity of windborne insect migration highlight its importance and impacts on Sahelian and neighboring ecosystems.Biotechnology and Biological Sciences Research Council (BBSRC)National Institutes of Health (NIH)U.S. Armylorida Department of Agriculture and Consumer Services-Division of Plant Industr

Intensifying Maize Production Under Climate Change Scenarios in Central West Burkina Faso

Combination of poor soil fertility and climate change and variability is the biggest obstacle to agricultural productivity in Sub-Saharan Africa. While each of these factors requires different promising adaptive and climate-resilient options, it is important to be able to disaggregate their effects. This can be accomplished with ordinary agronomic trials for soil fertility and climate year-to-year variability, but not for long-term climate change effects. In turn, by using climate historical records and scenario outputs from climate models to run dynamic models for crop growth and yield, it is possible to test the performance of crop management options in the past but also anticipate their performance under future climate change or variability. Nowadays, the overwhelming importance given to the use of crop models is motivated by the need of predicting crop production under future climate change, and outputs from running crop models may serve for devising climate risk adaptation strategies. In this study we predicted yield of one maize variety named Massongo for the time periods 1980–2010 (historical) and 2021–2050 (2030s, near future) across agronomic practices including the fertilizer input rates recommended by the national extension services (28 kg N, 20 kg P, and 13 kg K ha−1). The performance of the crop model DSSAT 4.6 for maize was first evaluated using on-farm experimental data that encompassed two seasons in the Sudano-Sahelian zone in six contrasting sites of Central West Burkina Faso. The efficiency of the crop model was evidenced by reliable simulations of total aboveground biomass and yields after calibration and validation. The root-mean-square error (RMSE) of the entire dataset for grain yield was 643 kg ha−1 and 2010 kg ha−1 for total aboveground biomass. Three regional climate change projections for Central West Burkina Faso indicate a decrease in rainfall during the growing period of maize. All the three scenarios project that the decrease in rainfall is to the tune of 3–9% in the 2030s under RCP4.5 in contrast to climate scenarios produced by the regional climate model GCM ICHEC-EC-Earth which predicted an increase of rainfall of 25% under RCP8.5. Simulations using the CERES-DSSAT model reveal that maize yields without fertilizer show the same trend as with fertilizer in response to climate change projections across RCPs. Under RCP4.5 with output from the climate model ICHEC-EC-Earth, yield can slightly increase compared to the historical baseline on average by less than 5%. In contrast, under RCP8.5, yield is increased by 13–22% with the two other climate models in fertilized and non-fertilized plots, respectively. Nevertheless, the average maize yield will stay below 2000 kg ha−1 under non-fertilized plots in RCP4.5 and with recommended mineral fertilizer rates regardless of the RCP scenarios produced by ICHEC-EC-Earth. Giving the fact that soil fertility improvement alone cannot compensate for the adverse impact of future climate on agricultural production particularly in case of high rainfall predicted by ICHEC-EC-Earth, it is recommended to combine various agricultural techniques and practices to improve uptake of nitrogen and to reduce nitrogen leaching such as the splitting of fertilizer applications, low-release nitrogen fertilizers, agroforestry, and any other soil and water conservation practices

Integrated pearl millet management in the Sahel : effects of legume rotation and fallow management on productivity and Striga hermonthica infestation

Increasing population density and food needs in the Sahel are major drivers behind the conversion of land under natural vegetation to arable land. Intensification of agriculture is a necessity for farmers to produce enough food. As manure is scarce and fertilizers expensive, this study looks into the potential role of cowpea (Vigna unguiculata L.) and short duration fallow in maintaining soil fertility and productivity and in reducing the major weed problem Striga hermonthica (Del.) Benth. The research was carried out `on-farm¿ in a traditional millet (Pennisetum glaucum (L.) R.Br.) growing area in the Malian Sahel, near Bankass. The four year experiment combined 0, 2, 5, and 7 years of preceding fallow with (i) 4 years of millet, (ii) 1 year of cowpea + 3 years of millet, and (iii) 1 year of cowpea + 3 years of millet/cowpea inter-cropping. Total millet production (4 years) was 1440 kg ha¿1 for all systems with 2, 5 or 7 years of preceding fallow against 1180 kg ha¿1 for systems without fallow. Cowpea grain production showed no significant differences between fallow treatments. Over 4 years, all cropping systems produced similar total amounts of millet grain, implying that the millet `lost¿ during the year with a pure cowpea crop in treatments (ii) and (iii) was compensated within three years, while the cowpea grain production was an additional benefit. Such compensation was however not observed for increasing number of preceding fallow years, showing that there is no additional production benefit in 5¿7 years of fallow as compared to 2 years. The soil organic carbon content decreased more slowly in treatments with a cowpea pure crop in 1998 than in the millet pure crop, while overall higher contents were observed after preceding fallow also after four years of cropping. Striga hermonthica infestation decreased linearly with duration of preceding fallow, but also after seven years of fallow and one year of cowpea the hemi-parasitic weed still re-appeared. Overall the intensification through a cowpea pure crop and cowpea intercrop in these millet-based systems improved production and a number of other characteristics of the system, making it more viabl

Effects of cultivation practices on spatial variation of soil fertility and millet yields in the Sahel of Mali

The article provides a quantitative analysis of temporal variation in fallow characteristics, and spatial variation in fallow distribution, pearl millet (Pennisetum glaucum) yield and soil fertility in three villages in the Bankass area in Sahelian Mali. Plots of 5 m × 5 m along four transects were installed at 10, 50, 100, 200, 500, 1000 and 2000 m from the edge of the village compounds to the outer boundary of the village territory. We found that currently, fallow is practiced only in ‘bushfields’, which are further than 200 m away from the dwellings. Significant increases in the amount of organic C and soil nutrients (N, P and K) were found with increasing fallow duration. This was due to gradual accumulation of organic matter from fallow vegetation and the presence of leguminous species. Soil nutrients and organic C were higher in homefields

Amélioration de l'efficacité énergétique d'un refroidisseur à partir de la granulométrie du bilan des débits d'air

International audienc

Participatory analysis of vulnerability and adaptation to climate change: a methodological guide for working with rural communities. ICRAF Occasional Paper No. 19

This methodological guide was designed to help researchers and development workers to conduct a participatory analysis of vulnerability and adaptation to climate change (PAVACC) with rural communities, and to develop action plans that reflect the concerns of the rural communities. The approach helps rural communities to assess their vulnerability to climate change, and to identify and plan appropriate activities to reduce their vulnerability. In addition, it helps them to organize and analyze information about the vulnerability and resilience of their community, households and individuals, and to use local knowledge about coping strategies to help them adapt to climate change

Analyse participative de la vulnérabilité et de l’adaptation aux changements climatiques: un guide méthodologique

La vulnérabilité au changement climatique est un indicateur de sensibilité ou d’incapacité d’un système à faire face aux effets défavorables des variabilités et risques climatiques. Les communautés rurales connaissent mieux leurs situations. Elles ont leur façon de percevoir le phénomène de changement climatique; alors toute analyse de la vulnérabilité aux risques climatiques devrait s’appuyer sur leurs connaissances des conditions locales