Background Seasonal malaria chemoprevention (SMC) with Sulfadoxine-pyrimethamine plus amodiaquine (SPAQ) reduces malaria in children under five, but substantial burden remains among children 5–9 years. Emerging SP/AQ resistance and adherence challenges underscore the need for alternative regimens. Dihydroartemisinin-piperaquine (DHAPQ) is a promising option, although evidence from multi-season programmatic settings in the Sahel is limited. We aimed to evaluate the effectiveness and safety of DHAPQ compared with SPAQ when SMC was extended to children aged 3 months to 9 years. Methods We conducted a two-year, three-arm, cluster-randomized crossover trial in nine health-catchment clusters in Mali. Clusters received standard SPAQ SMC (<5 years), extended-age SPAQ (<10 years), or (3) extended-age DHAPQ (<10 years), crossing over to a different regimen in year two. The primary outcome was the incidence of clinical malaria, analyzed using mixed-effects negative binomial models that accounted for clustering, period effects, and recurrent events. Non-inferiority was predefined as an upper 95% CI < 1.25. Findings Among 12,854 children contributing 18,912 person-years, DHAPQ reduced malaria incidence by 70% (95% CI 58–79) in children under five and 90% (84–94) in those 5–9 years compared with standard SPAQ. DHAPQ was non-inferior to extendedage SPAQ (HR 0.62; 95% CI 0.48–0.81), with higher coverage and no serious adverse events. Interpretation Extending SMC to children aged 5–9 years substantially reduced malaria burden. DHAPQ was safe, effective, and operationally feasible, supporting its consideration as an alternative to SPAQ where adherence or resistance threatens SMC effectiveness. Funding NIH/NIAID—ICEMR-WAF.

Background: Malaria transmission persists in Sahelian West Africa, with asymptomatic Plasmodium falciparum infections acting as a reservoir. Yet malaria epidemiology and research focus heavily on clinical cases. It remains unclear whether parasites causing clinical infections are genetically representative of the asymptomatic reservoir. Methods: A one-year cohort study (2021 and 2022) was conducted in four villages in the Kedougou district of Senegal and two villages in the Kati district of Mali, collecting 1,133 P. falciparum-positive samples from asymptomatic and clinical infections. Using parasite molecular barcodes and whole-genome sequencing, we estimated multiplicity of infection (MOI), runs of homozygosity (RoH), and identity-by-descent (IBD) to compare parasite populations between infection types and across age groups. Results: A total of 226 whole genomes and 728 barcodes were analysed, representing 78.2% (570/729) of clinical cases and 21.7% (158/728) of asymptomatic infections. MOI was high, with over 50% of infections being polyclonal, and did not differ by age or infection status. IBD analysis revealed a highly diverse parasite population, with transmission clusters including both asymptomatic carriers and clinical cases. Drug resistance allele frequencies were similar between groups. Conclusion: Overall, we found no evidence of genetic differentiation between parasites from clinical and asymptomatic infections, suggesting that clinical cases reflect the broader parasite population sustaining transmission. These findings provide a basis for linking genomic metrics with epidemiological factors and for monitoring the impact of future interventions on the parasite population. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Fondation pour la Recherche Medicale FRM EQU202303016290. Excellence Initiative of Aix Marseille University AMIDEX, a French Investissements d Avenir programme : the MARS project (AMidex International 2018). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Written informed consent was obtained from all participants, or from parents or legal guardians for those under 18 years old. In Senegal, inhabitants not included in the cohort provided specific informed consent for dried blood spot collection when they presented with a clinical malaria episode. The study protocol received ethical approval from the National Ethics Committee for Health Research of Senegal (No. 0000052/MSAS/DPRS/CNERS) and the Ethics Committee of the University of Sciences, Techniques and Technologies of Bamako, Mali (protocol No. 2020/297/CE/FMOS/ FAPH). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors

Background:Despite significant progress, malaria remains a major challenge in Mali, due to heterogeneous transmission. The WHO 'High Burden to High Impact' strategy advocates targeting of high-transmission areas. This study aimed to identify clinical malaria hotspots in two health areas within the Kolondieba district with differing transmission levels. Materials and Methods:A retrospective cross-sectional study analysed 35,934 confirmed malaria cases extracted from consultation registers between 2019 and 2021 in the health areas of Kadiana (high risk) and Kolondieba Central (moderate risk). Transmission periods were determined in each zone by analysing variations in mean incidence trends, and high-risk clusters (hotspots) were identified using Kulldorff's method according to these periods. Results:Transmission periods and hotspot identification (2019-2021) revealed distinct dynamics between the two health areas. In Kadiana, the majority of clusters remained stable, with persistent hotspots across all eight periods (Kadiana and Tienkourani; RR: 1.8-6.3). In Kolondieba Central, hotspot dynamics evolved from a localised configuration (1 to 2 villages) towards spatial expansion, with more extensive clusters appearing during the final periods (RR: 1.7-2.2). Kolondieba town remained a persistent hotspot. Conclusions:This study confirms the heterogeneity of transmission at a fine scale, with stable hotspots even in both moderate and high-risk areas. It is essential to focus on human mobility to guide malaria control interventions.

Malaria is a public health threat in Mali, with high morbidity (37%) and mortality (25%) rates. Malaria risk stratification is needed to identify different risk transmission and select interventions, especially in resource-limited contexts. For the new National Strategic Plan, we updated stratification with World Health Organization (WHO) recommendation and presents the selection of interventions based on stratification. Data collection covered all the 75 Health Districts (HDs) in the country for the period 2018-2022. This was further supplemented by national survey data on parasitology and entomology in Mali. To estimate the adjusted incidence, the analysis considered health data reporting, malaria diagnostic positivity and health facility attendance rates at health district level to malaria cases estimated. Mixed interventions were defined based on adjusted incidence, prevalence, seasonality, vector resistance to insecticides and parasite distribution by Health Districts or region according to data available. Four strata have been defined according to the 2017 WHO Malaria Elimination Framework. Most HDs (54) fall within the highest and moderate transmission areas, covering 84% of the population (about 18 million) located in the southern and central regions. A total of 10 intervention packages were selected. We identified 61 out of 75 eligible HDs for the LLINs mass distribution campaign, 57 HDs for SMC, 67 for IPTp including community IPTp and 19 HD for vaccination. Geo-epidemiology of malaria risk and selection of interventions identified 55 districts with high malaria burden where major interventions will continue, specifically SMC, distribution of ITNs, and gradual introduction of vaccination in some of these 19 districts. Malaria stratification was critical for strategic planning and appropriate deployment of malaria control interventions in Mali.

Introduction:Since the confirmation of the first case of SARS-CoV-2 in China in December 2019, all countries in the world have been affected by this pandemic. After one (1) year of the pandemic in Mali, two outbreaks were observed. The objective of this study was to characterize the demographic and clinical variability of cases between the two episodes. Materials and Methods:This was a secondary analysis of data from patients with COVID-19 in Mali during the first and the second outbreaks. The anonymous list of all COVID-19 cases confirmed by RT-PCR was used. Pearson's and Student's Chi-square tests were performed with a significance level of 5%. Results:During the study period, 2567 and 4610 people were confirmed positive for SARS-CoV-2 respectively for the first and second epidemics with a similar average age (40.4 years ±17.6 for the first against 39.9 years ± 17.2 for the second). The male sex had a higher proportion in the two outbreaks but different between the waves (69% for the first outbreak and 60% for the second, p < 0.001). The proportion of symptomatic patients was significantly different between the two waves (6.2% for the first wave versus 13.1% for the second wave, p < 0.001). The proportions of cases by age group were significantly similar between the two waves (0-20 years: 10.1% vs 11.3%; 21-40 years: 46.3% vs 45.7%; 41-60 years: 28.2% vs 29.4%; Over 60: 15.4% vs 13.5%; p = 0.063). Death rate was higher in the first episode compared to the second (5.8% versus 4.3%; p = 0.003). Conclusion:SARS-CoV-2 infection in Mali had a significant variation in symptomatology between the two waves, more highlighted in the second. The proportions of age groups of patients with COVID-19 did not vary between the two outbreaks. Death rate was higher in the first wave.

Malaria is a common disease in Mali associated with high morbidity and mortality. To improve malaria control, it is important to evaluate how current interventions affect the genetic make-up of circulating parasites. We analyzed the genomes of recently collected Plasmodium falciparum isolates across Mali to understand transmission dynamics, parasite relatedness, and selection pressures affecting parasite populations. We sequenced clinical isolates (n=458) collected in 2023 from 13 heath districts across Mali using molecular inversion probe (MIP) panels targeting key drug resistance mutations and common SNPs across the P. falciparum genomes. We also MIP sequenced polymorphisms in the human β-globin gene in study participants to assess sickle haemoglobin mutation. We performed complexity of infection (COI), identity-by-descent (IBD), principal component (PCA), selection signal, and haplotype analyses. The prevalence of polygenomic infections ranged from 13.0% in the north, dominated by the Sahara Desert, to 44.0% in the south, with tropical wet and dry climates. Parasites collected from the same district showed low levels of genetic relatedness with a mean IBD of <0.2. There was a network of parasite connectivity between sites across the country, and IBD between districts was inversely correlated with geographical distance separating them ( P=0.006, R=-0.28 ). The strongest selection signal was detected around the chloroquine-resistance transporter ( pfcrt ) gene. PCA in monogenomic samples (n=242) separated a cluster of parasites (n=56) from the main population showing a specific selection signal around acetyl-coA synthetase ( pfacs8) . The ACS8 Y40F mutation, associated with sickle haemoglobin and also known as Pfsa1 , was detected in all the samples from this cluster. Higher prevalence of PfCRT K76T mutation (55.8%, n=104) and sickle cell trait (8.4%, n=83) were measured in samples carrying Pfsa1 compared to wild type (26.6%, n=342 and 1.3%, n=237; respectively, P<0.005 , Chi-square test). Samples carrying both Pfsa1 and PfCRT K76T exhibited higher IBD across chromosomes, and one major haplotype was identified around pfcrt in 80% of K76T mutants, in which 64% of Pfsa1 was detected. Our nationwide genomic profiling of malaria parasites in Mali reveals clear selective sweeps linked to drug pressure and host genetics highly contributing to shaping the genetic make-up of parasite populations, and confirms the association of Pfsa1 with sickle haemoglobin. The Pfsa1 -PfCRT 76T linkage highlights a critical axis of parasite adaptation that warrants close surveillance.

RÉSUMÉ Contexte. La fièvre jaune persiste comme problème de santé publique au Mali, avec des flambées récurrentes en zones de savane malgré une couverture vaccinale élevée (≥90 %), censée induire une immunité collective (>80 %) et interrompre la transmission homme-moustique. Cette étude évalue la séroprévalence amarile dans quatre districts pour identifier les lacunes immunitaires expliquant cette résurgence. Méthodes. Une étude transversale de séroprévalence a été menée en 2023 auprès de 432 volontaires afébriles (>14 ans) résidant à Kita, Bamako, Bougouni et Kadiolo. Le statut immunitaire a été déterminé par test de neutralisation par réduction de plages (PRNT, seuil ≥1:10). Les données ont été analysées via SPSS v.27 (IC 95 % ; p<0,05). Résultats. La séroprévalence globale était de 74,1 % (IC 95 % : 69,8–78,2), variant significativement entre les districts (p<0,001) : Kita (85,0 % ; IC : 78,4–90,1), Bamako (79,2 % ; IC : 72,0–85,3), Bougouni (73,5 % ; IC : 66,1–79,9) et Kadiolo (64,0 % ; IC : 56,2–71,2). Seul Kita dépassait le seuil d’immunité collective requis (≥80 %). Les participants non vaccinés (n=89 ; 20,6 %) présentaient une séroprévalence de 32,6 % (IC : 23,1–43,4), reflétant une exposition antérieure au virus sauvage. Conclusion. Bien que la couverture vaccinale nominale soit élevée, l’immunité collective réelle reste insuffisante dans trois districts sur quatre (<80 %), favorisant la persistance de chaînes de transmission. Ces écarts pourraient s’expliquer par des biais de couverture (vaccins non immunogènes, stockage inadéquat) ou une mobilité accrue de populations non vaccinées. Des campagnes ciblées dans les zones à faible séroprévalence (Kadiolo, Bougouni), associées à une surveillance renforcée des cas sporadiques, sont essentielles pour atteindre l’élimination. ABSTRACT Background. Yellow fever remains a public health challenge in Mali, with recurrent outbreaks in savannah regions despite high reported vaccination coverage (≥90%), expected to induce herd immunity (>80%) and interrupt human-mosquito transmission. This study assesses yellow fever seroprevalence in four districts to identify immunity gaps driving resurgence. Methods. A cross-sectional seroprevalence study was conducted in 2023 among 432 afebrile volunteers (>14 years) residing in Kita, Bamako, Bougouni, and Kadiolo. Immune status was determined via plaque reduction neutralization test (PRNT, threshold ≥1:10). Data were analyzed using SPSS v.27 (95% CI; p<0.05). Results. Overall seroprevalence was 74.1% (95% CI: 69.8–78.2), varying significantly across districts (p<0.001): Kita (85.0%; CI: 78.4–90.1), Bamako (79.2%; CI: 72.0–85.3), Bougouni (73.5%; CI: 66.1–79.9), and Kadiolo (64.0%; CI: 56.2–71.2). Only Kita exceeded the herd immunity threshold (≥80%). Unvaccinated participants (n=89; 20.6%) had a seroprevalence of 32.6% (CI: 23.1–43.4), indicating prior wild virus exposure. Conclusion. Despite nominal high vaccination coverage, actual herd immunity remains suboptimal in three districts (<80%), sustaining transmission chains. Discrepancies may stem from coverage biases (non-immunogenic vaccines, inadequate storage) or mobility of unvaccinated populations. Targeted campaigns in low-seroprevalence areas (Kadiolo, Bougouni), coupled with enhanced surveillance of sporadic cases, are critical to achieving elimination.

The increase in malaria incidence and the reduction of funding for malaria control have highlighted the need to step up efforts in the fight against malaria in Mali. To further refine the malaria control strategy implemented in the country, this study aimed to evaluate the impact of control interventions at the health district level on malaria incidence in the general population. Malaria, rainfall, and intervention data were collected for the 75 health districts of Mali for the period from April 2017 to March 2022. The impact of the different control interventions on malaria incidence in the general population was assessed at the health district level with a Generalized Additive Mixed Model considering rainfall. Although coverage rates varied widely between health districts, most interventions showed an improvement in coverage over the study period. Two interventions had a small impact on incidence: long-lasting insecticidal net mass distribution (LLIN), with a reduction rate of 2.2 ‰ for an adjusted coverage rate from 30.0 to 79.0

Introduction Seasonal malaria chemoprevention (SMC) reduces malaria incidence in children under five in Mali, yet transmission persists likely due to chronic low-density Plasmodium falciparum infections which are often asymptomatic and undetectable by routine field diagnostics. This study characterises the P. falciparum reservoir in two distinct Malian settings with routine SMC. Methods We conducted a cohort study (2021-2022) of 670 participants from four Malian villages (two in Kati, two in Dire). During four survey visits (T0-T3), infection was detected using rapid diagnostic tests (RDTs) and quantitative PCR (qPCR). Weekly clinical malaria incidence, P. falciparum PCR prevalence, parasite density and multiplicity of infection (eMOI) were calculated. We evaluated factors associated with P. falciparum carriage using multivariable regression. Results In Kati, incidence followed rainfall, peaking in 20–24-year-olds (T1–T2), while in Dire it peaked during Niger River flooding, mainly in 5–24-year-olds (T2-T3). qPCR prevalence reached 33.3% in Kati and 60% in Dire, RDT sensitivity was low, over half of the infections were <100 parasites/μL and eMOI was higher in Kati peaking in 10–25 year-olds. Discussion Our findings show that asymptomatic and subpatent infections sustain transmission in Mali with 5–24 years olds as major parasite reservoirs due to their high infection prevalence, parasite densities, and multiplicity. Predominance of polyclonal infections indicates ongoing exposure despite reduced clinical incidence. Conclusion SMC has shifted malaria incidence from under-fives to older age groups now sustaining transmission. Targeting asymptomatic carriers beyond SMC coverage is essential to further reduce transmission and advance elimination in seasonal settings. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study used data produced within the MARS project (A*Midex International 2018), funded by the Excellence Initiative of Aix Marseille University, A*MIDEX ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Mali Ethics Committee gave ethical approval for the protocol for this study (protocol No. 2020/297/CE/FMOS/ FAPH). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors

BACKGROUND:In Sahelian Africa, successful interventions against malaria include vector control, improved access to care, and seasonal malaria chemoprevention (SMC) in children. However, malaria incidence has increased in the past 5 years. Up-to-date evidence is necessary to design additional interventions and restore progress towards elimination. In this study, we aimed to describe subclinical Plasmodium falciparum infections in the general population and understand the changes in prevalence, parasite densities, and clinical incidence across age groups and seasons, and to identify factors associated with P falciparum carriage in Kedougou, Senegal's most affected region. METHODS:We included all individuals older than 6 months from randomly selected households of four villages in a 1-year open cohort. During four surveys spanning the dry and wet seasons, we collected sociodemographic and behavioural data, and detected P falciparum using quantitative PCR on capillary dried blood samples. We analysed risk factors associated with P falciparum carriage using multilevel logistic regression. FINDINGS:We included 763 participants from 69 households, and they were followed up from April 13, 2021, to March 30, 2022. P falciparum prevalence was lowest in SMC-eligible children (aged <10 years) and remained below 10% across wet and dry seasons. Older age groups had similar dry season prevalence at baseline (10-15%). During the wet season, prevalence increased in individuals aged 15-24 years (32·1%) and 35-49 years (24·7%). The highest clinical burden was in participants aged 10-14 years (527 cases per 1000 person-years) and 15-19 years (631 cases per 1000 person-years), over five-fold higher than children aged 6 months to 4 years (93 cases per 1000 person-years). Outdoor night-time activity was associated with P falciparum infection. INTERPRETATION:In this setting, ongoing intensive control reduced malaria in SMC-eligible children. Older individuals bear an important clinical burden and harbour high prevalence during the wet season. Elimination-oriented interventions must tackle the parasite reservoir, involving whole communities and specifically young adults. FUNDING:Excellence Initiative of Aix-Marseille University-A*MIDEX, a French Investissements d'Avenir programme: the MARS project (A*Midex International 2018). TRANSLATION:For the French translation of the abstract see Supplementary Materials section.

Rift Valley fever (RVF) is a zoonotic disease with a human mortality rate of up to 50%. Its prevalence in cattle in Timbuktu, in northern Mali, has been estimated at 10%. In this region, close contact between humans and animals increases the likelihood of exposure to the Rift Valley fever virus (RVFV). Despite this potential risk, no human epidemic has been reported in Timbuktu to date. To address this gap, we conducted a population-based study to estimate the seroprevalence of RVF in five districts of the Timbuktu region. Using the competitive ELISA technique, we found an overall human seroprevalence of RVF of 10.7% (95% CI: 8.8% - 12.8%) among 983 volunteers, closely like seroprevalence observed in cattle. These findings clearly demonstrated the circulation of the RVFV in the human population in all districts of the Timbuktu region and highlight the need to strengthen public health strategies to better prepare for potential future outbreaks.

Introduction Malaria is a public health threat in Mali, with high morbidity (37%) and mortality (25%) rates. Malaria risk stratification is needed to identify different transmission zones and prioritize the interventions, especially in resource-limited contexts. For the new National Strategic Plan, we updated stratification with World Health Organization (WHO) recommendation. This study presents the selection of interventions based on stratification. Method Data collection covered all the 75 Health Districts (HDs) in the country for the period 2018-2022. This was further supplemented by national survey data on parasitology and entomology in Mali. To estimate the adjusted incidence, the analysis considered health data reporting, malaria diagnostic positivity and health facility attendance rates at health district level to malaria cases estimated. Mixed interventions were defined based on adjusted incidence, prevalence, seasonality, vector resistance to insecticides and parasite distribution by Health Districts or region according to data available. Results Four strata have been defined according to the 2017 WHO Malaria Elimination Framework. Most HDs (54) fall within the highest and moderate transmission areas, covering 84% of the population (about 18 million) located in the southern and central regions. A total of 19 intervention packages were selected and adapted. We identified 61 out of 75 eligible HDs for the LLINs mass distribution campaign, 57 HDs for SMC, 67 for IPTp including community IPTp and 19 HD for vaccination. Conclusion A half of Malian population live in high-risk areas. These districts require a continuous intensification of interventions. Malaria stratification was critical for strategic planning and appropriate deployment of malaria control interventions in Mali. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial NA ### Funding Statement No funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was approved by the National Malaria Control Program (042/MSDS-SG/NMCP, 14 January 2023), in accordance with ethics and medical research in Mali. Data was collected through routine disease surveillance. Only aggregated data were extracted from the DHIS2 platform with the agreement of the National Malaria Control Program. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data can be shared on request, with reasons.

In November 2023, three years after the onset of the pandemic, Mali officially recorded 33,160 confirmed COVID-19 cases and 743 related deaths. Tombouctou health district, following Bamako, the capital city, emerged as the second major hotspot with over 532 confirmed cases. However, these figures likely underestimate the true scale of the epidemic due to limited healthcare access and diagnostic capacity. This study aimed to describe the early trajectory of the epidemic, estimate seroprevalence, and identify factors associated with COVID-19 in the Tombouctou health district. A multi-level study was conducted in January 2021. First, the epidemic dynamics in Tombouctou were analyzed, estimating the basic reproduction number (R0) using daily case time series. Additionally, a cross-sectional survey was conducted, involving 419 households and 1102 participants, allowing for seroprevalence estimation by age and gender. A face-to-face questionnaire collected information on living conditions and knowledge, attitudes, behaviors and practices, regarding the epidemic. Factors associated with SARS-CoV-2 seropositivity were determined using generalized additive mixed models (GAMMs), adjusted to the variable under study and the level of analysis. We estimated an R0 of 2.08 [1.46-2.93]. The crude seroprevalence of SARS-CoV-2 was 33.5% (309/923, 95% CI: 30.4% to 36.6%). Living in a household where someone had been diagnosed with COVID-19 [Incidence Rate Ratio (IRR)=5.47; 95% CI (4.51 to 6.64)], traditionally wealth households [IRR = 2.02; 95% CI (1.23-3.33)], modernly wealth households [IRR = 1.33; 95% CI (1.02 - 1.72)], and older age (per year) [Adjusted Odds Ratio (AOR)=1.02 (1.00 to 1.03)] were significantly associated with seropositivity. Our analysis highlighted the active circulation of SARS-CoV-2 in Tombouctou, with higher seroprevalence observed among people from wealth households, as well as older age groups. The findings underscore the need for tailored and targeted approach focusing on specific households, demographics and settings.

.Introduction : La fièvre jaune est une arbovirose dont les épidémies ont été notifiées fréquemment dans les régions de savane au Mali avec des taux de mortalité atteignant 47 %. Contrairement aux régions de savane, les cas de fièvre jaune sont rarement notifiés dans les localités sahéliennes du Mali. Dans un contexte de changement climatique, d’augmentation de la capacité vectorielle des moustiques Aedes responsables de la transmission de la fièvre jaune, et de la forte mobilité de la population à cause des conflits armés, le virus de la fièvre jaune circulerait dans les localités sahéliennes du Mali.Objectif : Estimer la séroprévalence de la fièvre jaune dans les localités sahéliennes du Mali. Méthodologie : c’était une étude transversale, conduite dans trois localités sahélienne du Mali : Diéma, Niono et Bandiagara. Au cours de cette étude, nous avons inclus 361 volontaires âgés de plus de 14 ans, chez qui nous avons collecté 5 millilitres de sang pour réaliser le test de neutralisation du virus. Résultats : Nous avons estimé la séroprévalence de la fièvre jaune à 51,2 % dans les régions sahéliennes du Mali. La séroprévalence de la fièvre jaune était comparable entre les hommes et les femmes : 52,1 % pour les hommes versus 50,9 % pour les femmes. Nous avons observé que le titre de neutralisation du virus augmentait avec l’âge. Conclusion : Ces résultats suggèrent le renforcement de la surveillance épidémiologique de la fièvre jaune en zone sahélienne du Mali.

Background:Malaria remains a significant public health challenge in Mali, particularly in endemic areas such as the Kolondieba health district. This study aimed to analyse the geo-temporal dynamics of clinical malaria transmission, identifying high-risk periods, vulnerable age groups and associated environmental and health determinants. Materials and Methods:A historical cohort study was conducted from 2019 to 2021 across 21 health facilities in the Kolondieba district. Epidemiological, climatic, and demographic data were analysed using geospatial tools (QGIS) and statistical software (R). The non-parametric Wilcoxon and Kruskall-Wallis tests were used to compare two means and population malaria incidence distribution, respectively. Results:The incidence of malaria exhibited seasonality influenced by precipitation and humidity, while elevated temperatures were associated with a decrease in malaria incidence. Periods of high transmission potential (HTP) last for 20-25 weeks annually (weeks 23-48) and peak around weeks 30-31. Malaria accounted for 53.71% of consultation reasons, with pronounced vulnerability observed in children aged 0-4 yrs, especially during high transmission periods. Spatial stratification revealed two risk levels: 5 health areas at moderate risk (incidence 251-450 cases/1000 inhabitants) and 16 at high risk (>450 cases/1000 inhabitants). Health center attendance was a more determining risk factor. Conclusion:This study highlights the spatial and temporal heterogeneity of malaria transmission in southern Mali, emphasising the necessity to target interventions during weeks 23-48 (June through November), among children <5 yrs of age, in health areas with high health centre attendance. The integration of socio-economic factors in future studies could refine control strategies.

Seasonal malaria chemoprevention (SMC) with sulfadoxine-pyrimethamine and amodiaquine is recommended by the World Health Organization since 2012 for clinical malaria prevention in children in the Sahelian region of Africa. In Senegal, SMC implementation began in 2013 and is given to children under 10 years old. This study aimed to describe clinical malaria incidence in the general population during routine SMC implementation and to analyse how SMC timing impacted clinical malaria dynamics in eligible children. We conducted an ecological study in the Kedougou region of Senegal in 27 villages included in the Bandafassi Health and Demographic Surveillance System (HDSS). We calculated weekly Plasmodium falciparum malaria incidence by age group using malaria case data recorded by community health workers and health-posts, and population denominators obtained from Bandafassi Health and Demographic Surveillance System. We used negative binomial generalized additive multilevel models to analyse the incidence of clinical episodes in children under 10 years during the expected SMC prophylactic period and at the end of the transmission period. Malaria incidence was strongly seasonal with a high transmission period starting in June. Children under SMC presented an overall lower incidence compared to older children and young adults. Among children eligible for SMC, the incidence was lowest for approximately 3 weeks after treatment administration and increased subsequently, suggesting a gradual loss of protection. At the end of the high transmission period, a higher malaria incidence was recorded from the 3 rd to 6 th week after the week of administration of the fourth (final) SMC round. While protecting children under 10 years, SMC warrants adjustment to reduce exposure before the next round, to increase protection of 5-9 years, and to cover the high transmission period completely. The addition of a 5 th round of SMC in 2023 was necessary to cover the end of the transmission season, but individual-level studies are required to ensure that drug efficacy and adequate dosing are maintained.

La schistosomiase est un problème de santé publique au Mali. En raison de la récente flambée de violence intercommunautaire au Mali, de nombreuses personnes se sont réfugiées dans les camps à la périphérie de Bamako. L’objectif de cette étude était d’évaluer la prévalence de la schistosomiase urinaire et des parasites intestinaux chez les enfants d'âge préscolaire et scolaire (EApS) des familles déplacées dans le district de Bamako. Nous avons mené une étude transversale chez les EApS de novembre à décembre 2023. L'enquête a couvert les camps des déplacés de Senou, Baguinéda et Niamana et les autochtones de Niamana. Les urines et les selles ont été examinées par la technique de filtration et le Kato-Katz, respectivement. Une goutte épaisse a été réalisée chez chaque enfant pour évaluer la prévalence du paludisme. Au total, 412 EApS ont été inclus avec 222 issus des déplacées et 190 des autochtones. La prévalence de Schistosoma haematobium était de 8,6% chez les déplacés comparée à 2,6% chez les autochtones, p<0,01. La prévalence des parasites intestinaux chez les enfants déplacés était de 1,8% versus les autochtones (4,7%), p=0,89. La prévalence du paludisme était plus élevée chez les déplacés (11,7%) que chez les autochtones (1,6%), p<0,001. Le taux d’hémoglobine était plus élevé mais pas significatif chez les déplacés (14%) que chez les autochtones (8%), p=0,051. En conclusion, la prévalence de la schistosomiase urinaire et du paludisme chez les EApS était plus élevée chez les enfants déplacés que chez les enfants autochtones au Mali. Schistosomiasis is a public health problem in Mali. Due to the recent outbreak of intercommunal violence in Mali, many people have taken refuge in camps on the outskirts of Bamako. The objective of this study was to assess the prevalence of urinary schistosomiasis and intestinal parasites among preschool and school-aged children (EApS) from displaced families in the Bamako district. We conducted a cross-sectional study among EApS from November to December 2023. The survey covered the camps of Senou, Baguinéda and Niamana and indigenous of Niamana. Urine and stool were examined by the filtration technique and Kato-Katz, respectively. A thick blood drop and hemoglobin were taken from each child to assess the prevalence of malaria. A total, 412 EApS were included with 222 from displaced and 190 from natives. The prevalence of Schistosoma haematobium was 8.6% in displaced compared to 2.6% in natives, p<0.01. The prevalence of intestinal parasites in displaced children was 1.8% versus natives (4.7%), p=0.89. Malaria prevalence was higher in displaced (11.7%) than natives (1.6%), p<0.001. The hemoglobin level was higher but not significant in the displaced (14%) than the natives (8%), p=0.051. In conclusion, the prevalence of urinary schistosomiasis and malaria in EApS was higher in displaced than natives’ children in Mali.