APSIM-based modeling approach to understand sorghum production environments in Mali.

Sorghum production system in the semi-arid region of Africa is characterized by low yields which are generally attributed to high rainfall variability, poor soil fertility, and biotic factors. Production constraints must be well understood and quantified to design effective sorghum-system improvements. This study uses the state-of-the-art in silico methods and focuses on characterizing the sorghum production regions in Mali for drought occurrence and its effects on sorghum productivity. For this purpose, we adapted the APSIM-sorghum module to reproduce two cultivated photoperiod-sensitive sorghum types across a latitude of major sorghum production regions in Western Africa. We used the simulation outputs to characterize drought stress scenarios. We identified three main drought scenarios: (i) no-stress; (ii) early pre-flowering drought stress; and (iii) drought stress onset around flowering. The frequency of drought stress scenarios experienced by the two sorghum types across rainfall zones and soil types differed. As expected, the early pre-flowering and flowering drought stress occurred more frequently in isohyets < 600 mm, for the photoperiod-sensitive, late-flowering sorghum type. In isohyets above 600 mm, the frequency of drought stress was very low for both cultivars. We quantified the consequences of these drought scenarios on grain and biomass productivity. The yields of the highly-photoperiod-sensitive sorghum type were quite stable across the higher rainfall zones > 600 mm, but was affected by the drought stress in the lower rainfall zones < 600 mm. Comparatively, the less photoperiod-sensitive cultivar had notable yield gain in the driest regions < 600 mm. The results suggest that, at least for the tested crop types, drought stress might not be the major constraint to sorghum production in isohyets > 600 mm. The findings from this study provide the entry point for further quantitative testing of the Genotype × Environment × Management options required to optimize sorghum production in Mali. Supplementary Information: The online version contains supplementary material available at 10.1007/s13593-023-00909-5.

Mapping Water Stress Incidence and Intensity, Optimal Plant Populations, and Cultivar Duration for African Groundnut Productivity Enhancement.

Groundnut production is limited in Sub-Saharan Africa and water deficit or "drought," is often considered as the main yield-limiting factor. However, no comprehensive study has assessed the extent and intensity of "drought"-related yield decreases, nor has it explored avenues to enhance productivity. Hence, crop simulation modeling with SSM (Simple Simulation Modeling) was used to address these issues. To palliate the lack of reliable weather data as input to the model, the validity of weather data generated by Marksim, a weather generator, was tested. Marksim provided good weather representation across a large gradient of rainfall, representative of the region, and although rainfall generated by Marksim was above observations, run-off from Marksim data was also higher, and consequently simulations using observed or Marksim weather agreed closely across this gradient of weather conditions (root mean square of error = 99 g m-2; R2 = 0.81 for pod yield). More importantly, simulation of yield changes upon agronomic or genetic alterations in the model were equally predicted with Marksim weather. A 1° × 1° grid of weather data was generated. "Drought"-related yield reduction were limited to latitudes above 12-13° North in West Central Africa (WCA) and to the Eastern fringes of Tanzania and Mozambique in East South Africa (ESA). Simulation and experimental trials also showed that doubling the sowing density of Spanish cultivars from 20 to 40 plants m-2 would increase yield dramatically in both WCA and ESA. However, increasing density would require growers to invest in more seeds and likely additional labor. If these trade-offs cannot be alleviated, genetic improvement would then need to re-focus on a plant type that is adapted to the current low sowing density, like a runner rather than a bush plant type, which currently receives most of the genetic attention. Genetic improvement targeting "drought" adaptation should also be restricted to areas where water is indeed an issue, i.e., above 12-13°N latitude in WCA and the Eastern fringes of Tanzania and Mozambique.

Correction: Prevalence of Cutaneous Leishmaniasis in Districts of High and Low Endemicity in Mali.

[This corrects the article DOI: 10.1371/journal.pntd.0005141.].

Prevalence of Cutaneous Leishmaniasis in Districts of High and Low Endemicity in Mali.

Historically the western sahelian dry regions of Mali are known to be highly endemic for cutaneous leishmaniasis (CL) caused by Leishmania major, while cases are rarely reported from the Southern savanna forest of the country. Here, we report baseline prevalence of CL infection in 3 ecologically distinct districts of Mali (dry sahelian, north savanna and southern savanna forest areas). We screened 195 to 250 subjects from 50 to 60 randomly selected households in each of the 6 villages (four from the western sahelian district of Diema in Kayes region, one from the central district of Kolokani and one from the southern savanna district of Kolodieba, region of Sikasso). The screening consisted of: 1] A Leishmanin Skin Test (LST) for detection of exposure to Leishmania parasites; 2] clinical examination of suspected lesions, followed by validation with PCR and 3] finger prick blood sample to determine antibody levels to sand fly saliva. LST positivity was higher in the western district of Diema (49.9%) than in Kolokani (24.9%) and was much lower in Kolondieba (2.6%). LST positivity increased with age rising from 13.8% to 88% in Diema for age groups 2-5 years and 41-65 years, respectively. All eight PCR-confirmed L. major CL cases were diagnosed in subjects below 18 years of age and all were residents of the district of Diema. Exposure to sand fly bites, measured by anti-saliva antibody titers, was comparable in individuals living in all three districts. However, antibody titers were significantly higher in LST positive individuals (P<0.0001). In conclusion, CL transmission remains active in the western region of Mali where lesions were mainly prevalent among children under 18 years old. LST positivity correlated to higher levels of antibodies to sand fly salivary proteins, suggesting their potential as a risk marker for CL acquisition in Mali.

A double-blind randomized placebo-controlled clinical trial of squalamine ointment for tinea capitis treatment.

BACKGROUND: Novel treatments against for tinea capitis are needed, and the natural aminosterol squalamine is a potential topical antidermatophyte drug candidate. OBJECTIVES: This phase II randomized double-blind placebo-controlled clinical trial aimed at testing the efficacy and safety of a three-week squalamine ointment regimen for the treatment of tinea capitis. PATIENTS: Males aged 6-15 years presenting with tinea capitis were treated with either topical squalamine ointment or placebo for 3 weeks. The primary endpoint was complete clinical cure. The secondary endpoints were the occurrence of local and/or systemic adverse events, mycological cure, and partial clinical response. Prospective follow-up of clinical adverse events was performed daily. RESULTS: Five patients were treated with 1% squalamine ointment and 15 with placebo. No complete cure was observed. No clinical or biological adverse event was recorded. A significantly (p = 0.03) better hair-growth score, indicating a partial clinical improvement of the tinea capitis lesion, was observed in the patients treated with squalamine compared to those treated with placebo. CONCLUSION: This three-week squalamine ointment regimen was well tolerated and showed an encouraging partial clinical activity for the treatment of tinea capitis. Further studies are needed to evaluate the efficacy of topical squalamine alone against tinea corporis or in combination with a systemic antidermatophyte drug against tinea capitis.

Leishmania major, the predominant Leishmania species responsible for cutaneous leishmaniasis in Mali.

Leishmania major is the only species of Leishmania known to cause cutaneous leishmanisis (CL) in Mali. We amplified Leishmania DNA stored on archived Giemsa-stained dermal scraping slides obtained from self-referral patients with clinically suspected CL seen in the Center National d'Appui A La Lutte Contre La Maladie (CNAM) in Bamako, Mali, to determine if any other Leishmania species were responsible for CL in Mali and evaluate its geographic distribution. Polymerase chain reaction (PCR) amplification was performed using a Leishmania species-specific primer pair that can amplify DNA from L. major, L. tropica, L. infantum, and L. donovani parasites, possible causative agents of CL in Mali. L. major was the only species detected in 41 microscopically confirmed cases of CL from five regions of Mali (Kayes, Koulikoro, Ségou, Mopti, and Tombouctou). These results implicate L. major as the predominant, possibly exclusive species responsible for CL in Mali.

Delayed-type hypersensitivity to sand fly saliva in humans from a leishmaniasis-endemic area of Mali is Th1-mediated and persists to midlife.

Immunity to sand fly saliva in rodents induces a T(H)1 delayed-type hypersensitivity (DTH) response conferring protection against leishmaniasis. The relevance of DTH to sand fly bites in humans living in a leishmaniasis-endemic area remains unknown. Here, we describe the duration and nature of DTH to sand fly saliva in humans from an endemic area of Mali. DTH was assessed at 24, 48, 72, and 96 hours post bite in volunteers exposed to colony-bred sand flies. Dermal biopsies were obtained 48 hours post bite; cytokines were quantified from peripheral blood mononuclear cells (PBMCs) stimulated with sand fly saliva in vitro. A DTH response to bites was observed in 75% of individuals aged 1-15 years, decreasing gradually to 48% by age 45, and dropping to 21% thereafter. Dermal biopsies were dominated by T lymphocytes and macrophages. Abundant expression of IFN-γ and absence of T(H)2 cytokines establishes the T(H)1 nature of this DTH response. PBMCs from 98% of individuals responded to sand fly saliva. Of these, 23% were polarized to a T(H)1 and 25% to a T(H)2 response. We demonstrate the durability and T(H)1 nature of DTH to sand fly bites in humans living in a cutaneous leishmaniasis-endemic area. A systemic T(H)2 response may explain why some individuals remain susceptible to disease.

Dermatitis of the folds in black Africans in Bamako, Mali.

Dermatitis of the folds (intertrigo) is a frequent reason for attending consultations, particularly in Africa, where the hot and humid climate constitute an aggravating factor. It is a complex pathology with multiple and intricate etiologies. The aim of this study was to describe epidemiological and etiological aspects of dermatitis of the folds in black-skinned subjects in Bamako (Mali). We conducted a transversal descriptive survey of cases of localized dermatitis of the folds of the skin in dermatology clinics in Bamako. In total, 141 cases of intertrigo were identified: 96 female subjects (68%) and 45 male subjects. The average age of patients was 30 ± 18 years (2-80 years). The majority of patients were seen between March and June; 52% of patients had already received treatment before the consultation. The lesions affected skin folds of the groin area and/or area between the buttocks in 95 patients (57.4%), and folds of the armpits and area under the breasts were affected in 46 cases (42.6%). Eczema, erythrasma, and fungal disease were the most frequently observed pathologies. Of interest to this study is the topographical approach that a dermatologist must adopt when diagnosing certain forms of dermatitis. In populations with specific cultural practices, apart from a thorough knowledge of these specific factors, treatment of these conditions requires certain harmful attitudes and behaviors to be abandoned.

Pruritus in dermatological hospital in Bamako, Mali.

Pruritus is a symptom frequently encountered in dermatology consultations. For practitioners working in a tropical environment, particularly in Africa, the diagnosis of pruritus remains a constant problem. The aim of this study was to describe the epidemioclinical aspects and the etiologies of pruritus encountered at the dermatological hospital in Bamako. We conducted a prospective survey on a cohort of patients attending the Department of Dermatology at the Centre National d'Appui (CNAM-Ex Institut Marchoux) in the Fight against Disease over a 1-year period (June 1, 2009-May 31, 2010). Consequently, the study included every patient, whatever their age and gender, that agreed to take part in the survey and whose main reason for attending for a consultation was "pruritus." The clinical and biological data were entered and analyzed using Epi Info software, version 6.04 fr. A total of 232 patients (163 women, 69 men) attended because of pruritus out of 1761 overall patients (i.e., a prevalence of 13.17%). The mean age of the patients was 33 ± 19 years. Dermatological causes represented 95% of the etiologies. This work allowed us to observe the systemic causes of pruritus in the dermatological environment in Mali and greater likelihood of black women to attend because of pruritus.

[Etiology of acquired hypochromic patches in dermatological area in Mali]. / Etiologies Des Hypochromies Acquises En Milieu Dermatologique.

INTRODUCTION: In dark skin patients, hypopigmentation is the most disfiguring condition. Very few studies on hypochromic disorders have been conducted in specialized health centers. The present study is aimed to describe the etiologies of hypochromic patches in dermatological area, in Bamako. METHODS: We carried out a cross sectional study in the Dermatology Clinic of the "Centre National d'Appui à la lutte contre la Maladie (CNAM, Ex Institut Marchoux)". All acquired hypochromic patches (HP) were selected. HP was defined as a "skin patch lighter in pigmentation than normal surrounding skin with a diameter of at least 1 cm". The diagnosis was mainly based on clinical findings. RESULTS: The prevalence of HP was 3.42% and the main causes were seborrheic dermatitis (23.3%), pytiriasis alba (20.15%), vitiligo (18.9%), pityriasis versicolore (18.5%) and leprosy (12.6%). CONCLUSION: There are many causes of HP including leprosy, a disease though rare to date, but still prevalent in dermatological area.

Genetic diversity, structure, gene flow and evolutionary relationships within the Sorghum bicolor wild-weedy-crop complex in a western African region.

Gene flow between domesticated plants and their wild relatives is one of the major evolutionary processes acting to shape their structure of genetic diversity. Earlier literature, in the 1970s, reported on the interfertility and the sympatry of wild, weedy and cultivated sorghum belonging to the species Sorghum bicolor in most regions of sub-Saharan Africa. However, only a few recent surveys have addressed the geographical and ecological distribution of sorghum wild relatives and their genetic structure. These features are poorly documented, especially in western Africa, a centre of diversity for this crop. We report here on an exhaustive in situ collection of wild, weedy and cultivated sorghum assembled in Mali and in Guinea. The extent and pattern of genetic diversity were assessed with 15 SSRs within the cultivated pool (455 accessions), the wild pool (91 wild and weedy forms) and between them. F (ST) and R (ST) statistics, distance-based trees, Bayesian clustering methods, as well as isolation by distance models, were used to infer evolutionary relationships within the wild-weedy-crop complex. Firstly, our analyses highlighted a strong racial structure of genetic diversity within cultivated sorghum (F (ST) = 0.40). Secondly, clustering analyses highlighted the introgressed nature of most of the wild and weedy sorghum and grouped them into two eco-geographical groups. Such closeness between wild and crop sorghum could be the result of both sorghum's domestication history and preferential post-domestication crop-to-wild gene flow enhanced by farmers' practices. Finally, isolation by distance analyses showed strong spatial genetic structure within each pool, due to spatially limited dispersal, and suggested consequent gene flow between the wild and the crop pools, also supported by R (ST) analyses. Our findings thus revealed important features for the collection, conservation and biosafety of domesticated and wild sorghum in their centre of diversity.

Discrepant prevalence and incidence of Leishmania infection between two neighboring villages in Central Mali based on Leishmanin skin test surveys.

UNLABELLED: Apart from a single report, the last publication of cutaneous leishmaniasis (CL) in Mali dates back more than 20 years. The absence of information on the current status of CL in Mali led us to conduct a cohort study in Kemena and Sougoula, two villages in Central Mali from which cases of CL have been recently diagnosed by Mali's reference dermatology center in Bamako. In May 2006, we determined the baseline prevalence of Leishmania infection in the two villages using the leishmanin skin test (LST). LST-negative individuals were then re-tested over two consecutive years to estimate the annual incidence of Leishmania infection. The prevalence of Leishmania infection was significantly higher in Kemena than in Sougoula (45.4% vs. 19.9%; OR: 3.36, CI: 2.66-4.18). The annual incidence of Leishmania infection was also significantly higher in Kemena (18.5% and 17% for 2007 and 2008, respectively) than in Sougoula (5.7% for both years). These data demonstrate that the risk of Leishmania infection was stable in both villages and confirm the initial observation of a significantly higher risk of infection in Kemena (OR: 3.78; CI: 2.45-6.18 in 2007; and OR: 3.36; CI: 1.95-5.8 in 2008; P<0.005). The absence of spatial clustering of LST-positive individuals in both villages indicated that transmission may be occurring anywhere within the villages. Although Kemena and Sougoula are only 5 km apart and share epidemiologic characteristics such as stable transmission and random distribution of LST-positive individuals, they differ markedly in the prevalence and annual incidence of Leishmania infection. Here we establish ongoing transmission of Leishmania in Kemena and Sougoula, Central Mali, and are currently investigating the underlying factors that may be responsible for the discrepant infection rates we observed between them. TRIAL REGISTRATION: ClinicalTrials.gov NCT00344084.