[Dental caries in schools in the city of N'Djamena in Chad: Epidemiological aspects and oral habits in pupils aged from 6 to 12 years]. / Carie dentaire en milieu scolaire dans la ville de N'Djamena au Tchad : aspects épidémiologiques et habitudes bucco-dentaires chez des élèves âgés de 6 à 12 ans.

Background: Dental caries is a global disease that can have disabling effects. In Africa, its prevalence in schools is very variable, due to the great variability of food habits and oral hygiene. This study aimed to assess the prevalence of dental caries, associated factors, and to research oral pathologies associated with that dental decay in one circumscription of the city of N'Djamena. Material and methods: This was a cross-sectional study conducted in 3 schools in the 7th borough of the city of N'Djamena. A total of 360 pupils aged between 6 and 12 years were recruited between October 2021 and September 2022. Each participant underwent to an oral examination which consisted in looking carefully at the pupil's face (cheeks, lips) to note any deformities or possible facial asymmetry, and to check for any sensation of pain in any part of the face. In another hand, the oral examination aimed to look for any decay on all the teeth and determine the category and class of it. Finally, the personal data (age, sex, class, parents' occupations) of each participant and the results of his oral examination were collected into a database and analyzed. Results: A total of 185 pupils had at least one decayed tooth, giving a prevalence rate of 51.4%. Among them, 45% had at least 2 decayed teeth. The school attended and snacking between meals were significantly associated with the presence of caries (p<0.05). Teeth 36 (lower left first molar) and 46 (lower right first molar) were the most often affected by caries (21% and 22% respectively). The mixt DMF index was 0.6 and the overall frequency of decayed teeth was 51.9%. According to Black's classification, class II caries was the most prevalent (48%), while according to Baume's classification, category II was the most prevalent (54%). The time of brushing, the material and the type of product used significantly influenced the appearance of caries (p<0.05). Participants with dental dyschromia had more tooth decay. Conclusion: Caries was prevalent in the targeted schools and represented a real problem for pupils. Implementing an oral health policy based on preventive dentistry by raising awareness among children and their parents would contribute to the proper education of pupils.

Barriers to the quality delivery of seasonal malaria chemoprevention in Chad and Burkina Faso: a qualitative exploration of caregivers and community distributors' perspectives.

BACKGROUND: Recommended since 2012 by the World Health Organization (WHO), seasonal malaria chemoprevention (SMC) is a community-based intervention to prevent malaria in children in African regions where malaria transmission follows a seasonal pattern. Following the publication of consolidated WHO guidelines for malaria, SMC is expected to reach more children in new geographies in future years. Though SMC has been shown to reduce malaria-related morbidity and mortality, there is potential for quality improvement of the intervention implementation. Assisted by ten quality standards from a framework developed by Malaria Consortium, this paper aims to better understand the quality of SMC implementation and identify potential barriers to quality delivery of SMC. METHODS: A qualitative thematic analysis on data collected after the annual SMC rounds implemented in Burkina Faso and Chad in 2019 was conducted. Sixteen focus group discussions conducted with caregivers and community distributors were analysed. Three selected quality standards for SMC delivery; planning and enumeration; community engagement; and administration of SMC medicines provided overarching quality themes under which subthemes were identified. RESULTS: Eight subthemes relating to the three quality standards were identified. Although SMC was well accepted by communities in both settings, common barriers to the quality delivery of SMC were identified including difficulty ensuring adherence to the SMC administration protocol; difficulties reaching mobile populations; concerns around adverse drug reactions; rumours, and concerns about SMC safety; and community distributors' working conditions. Context-specific barriers included: the suboptimal timeliness of the SMC round in Burkina Faso, and the lack of involvement of female caregivers in mobilization activities in Chad. CONCLUSION: In the context of increased adoption of SMC, this paper provides relevant insights and recommendations for the improved implementation of SMC programmes. These include the integration of strategies addressing communities' concerns around adverse drug reactions, gender-specific mobilization strategies, and attention to community distributors' working conditions. It also highlights the importance and utility of further, robust research on the quality of SMC delivery.

RéSUMé EN FRANçAIS: BACKGROUND: Recommandée depuis 2012 par l'Organisation mondiale de la santé (OMS), la chimioprévention du paludisme saisonnier (CPS) est une intervention communautaire visant à prévenir le paludisme chez les enfants dans les régions d'Afrique où la transmission du paludisme suit un schéma saisonnier. Suite à la publication des lignes directrices consolidées de l'OMS sur le paludisme, la CPS devrait toucher davantage d'enfants dans de nouvelles zones géographiques dans les années à venir. Bien qu'il ait été démontré que la CPS réduisait la morbidité et la mortalité liées au paludisme, il y a du potentiel pour améliorer la qualité de l'implémentation l'intervention. En s'appuyant sur un cadre de normes de qualité de la CPS développé par le Malaria Consortium, cette publication vise à mieux comprendre la qualité de la mise en œuvre de la CPS et à identifier les obstacles potentiels à la qualité de la mise en œuvre de la CPS. METHODS: Une étude qualitative basée sur l'analyse secondaire des données collectées après les tournées annuelles du SMC mises en œuvre au Burkina Faso et au Tchad en 2019 a été menée. Une analyse thématique de 16 discussions de groupe menées avec des parents/tuteurs et des distributeurs communautaires a été faite. Trois des éléments clés du cadre des normes de qualité pour le déploiement de la CPS ont fourni les thèmes de qualité principaux sous lesquels les sous-thèmes identifiés ont été placés. RéSULTATS: Huit sous-thèmes relatifs aux normes de qualité ; la planification, la sensibilisation et l'engagement des communautés ainsi que l'administration des médicaments de la CPS ont été identifiés. Bien que la CPS ait été bien acceptée par les communautés dans les deux contextes, des obstacles communs à la qualité du déploiement de la CPS ont été identifiés, notamment : la difficulté d'assurer le respect du protocole d'administration de la CPS; atteindre les populations mobiles ; les préoccupations concernant les effets indésirables des médicaments ; les rumeurs et les préoccupations concernant le SMC; et les conditions de travail des distributeurs communautaires. D'autres barrières spécifiques au contexte de déploiement ont été identifiées, telles que le choix sous-optimal de la période de déploiement au Burkina Faso ou le manque d'implication des mères/tutrices dans les activités de mobilisation au Tchad. CONCLUSION: Dans le contexte de l'adoption croissante de la CPS, cette publication fournit des informations et des recommandations pertinentes pour l'amélioration de la mise en œuvre des programmes de CMS, telles que l'intégration de stratégies répondant aux préoccupations des communautés concernant les effets indésirables des médicaments, les stratégies de mobilisation spécifiques au genre, et/ou l'attention portée aux conditions de travail des distributeurs communautaires. Cette publication souligne également l'importance et l'utilité des recherches en cours sur la qualité du déploiement de la CPS.

RESUMO EM PORTUGUêS: INTRODUçãO: Recomendada desde 2012 pela Organização Mundial de Saúde (OMS), a quimioprevenção sazonal do paludismo (SMC) é uma intervenção de base comunitária para prevenir o paludismo em crianças em zonas da África onde a transmissão do paludismo segue um padrão sazonal. Após a publicação das diretrizes consolidadas da OMS sobre o paludismo, espera-se que a SMC chegue a mais crianças em novas zonas geográficas nos próximos anos. Embora se tenha demonstrado que a SMC reduz a morbilidade e a mortalidade causadas pelo paludismo, há potencial para melhorar a qualidade da implementação da intervenção. Com ajuda dum quadro de padrões de qualidade para a SMC desenvolvido pelo Malaria Consortium, a presente publicação visa compreender melhor a qualidade da implementação da SMC e identificar potenciais barreiras à qualidade da implementação da SMC. MéTODOS: Foi realizado um estudo qualitativo baseado na análise secundária dos dados recolhidos após as rondas anuais da SMC implementadas no Burkina Faso e no Chade em 2019. Foi efectuado uma análise temática de 16 discussões de grupos focais realizadas com cuidadores e distribuidores comunitários. Tres padrões do quadro de normas de qualidade para a implementação da SMC forneceu os principais temas de qualidade sob os quais os subtemas identificados foram colocados. RESULTADOS: Foram identificados oito sub-temas relacionados com padrões de qualidade; planeamento; sensibilização e envolvimento da comunidade; e administração de drogas da SMC. Embora a SMC tenha sido bem aceita pelas comunidades em ambos os contextos, foram identificadas barreiras comuns à implementação duma SMC de qualidade, incluindo: a dificuldade de assegurar o cumprimento do protocolo de administração da SMC; atingir populações móveis; preocupações com reacções adversas aos medicamentos; rumores e preocupações com a SMC; e as condições de trabalho dos distribuidores comunitários. Foram identificados outros obstáculos específicos ao contexto de implantação, tais como a escolha subaproveitada do período de implantação no Burkina Faso ou a falta de envolvimento das cuidadoras femininas nas actividades de mobilização no Chade. CONCLUSãO: No contexto do aumento da adopção da SMC, esta publicação fornece informações e recomendações relevantes para melhorar a implementação de programas de SMC, tais como estratégias integradoras que abordam as preocupações da comunidade sobre reacções adversas aos medicamentos, estratégias de mobilização específicas de género, e/ou atenção às condições de trabalho dos distribuidores comunitários. Salienta igualmente a importância e a utilidade das investigaçãos em curso sobre a qualidade da implementação da SMC.

[Updating the northern tsetse distribution limit in Chad in the context of global change]. / Réactualisation de la limite nord de distribution des glossines au Tchad dans un contexte de changement global.

Background - Rationale: Tsetse flies (Diptera: Glossinidae) are obligate bloodfeeders that occur exclusively in Sub-Saharan Africa, where they are the vectors of trypanosomes causing HAT (human African trypanosomiasis) and AAT (African animal trypanosomiasis). In Chad, tsetse flies occur only in the most southern part of the country because of its favorable bioclimatic conditions. However, despite the importance of HAT and AAT in this country, very little is known about the current tsetse distribution, in particular its northern limit, which is of key importance for the surveillance of these diseases. Material and methods - Results: A total of 217 biconical traps were deployed in 2021 and 2022 from the West to the East around the formerly known northern limit, resulting in 1,024 tsetse caught belonging to three different taxa: Glossina morsitans submorsitans (57%), G. tachinoides (39%) and G. fuscipes fuscipes (4%). In addition to the information gathered on the presence/absence of each tsetse taxon, we show a strong North-South shift of the northen tsetse distribution limit as compared to the previous works from 1966 to 1996, and a growing spatial fragmentation in more and more discrete pockets of tsetse presence. Discussion - Conclusion: This North-South shift of the northern tsetse distribution limit in Chad is the likely consequence of the combined effect of severe draughts that affected the country, and increasing human pressure on land. This update of the tsetse northern limit will be of help to the national programmes in charge of HAT and AAT.

Modelling control strategies for pneumococcal meningitis outbreaks in the African meningitis belt.

INTRODUCTION: Pneumococcal meningitis outbreaks occur sporadically in the African meningitis belt. Outbreak control guidelines and interventions are well established for meningococcal but not pneumococcal meningitis. Mathematical modelling is a useful tool for assessing the potential impact of different pneumococcal control strategies. This work aimed to estimate the impact of reactive vaccination with pneumococcal conjugate vaccine (PCV) had it been implemented in past African meningitis belt outbreaks and assess their efficiency relative to existing routine infant immunisation with PCV. METHODS & RESULTS: Using recent pneumococcal meningitis outbreaks in Burkina Faso, Chad, and Ghana as case studies, we investigated the potential impact of reactive vaccination. We calculated the number needed to vaccinate to avert one case (NNV) in each outbreak setting and over all outbreaks and compared this to the NNV for existing routine infant vaccination. We extended previous analyses of reactive vaccination by considering longer-term protection in vaccinees over five years, incorporating a proxy for indirect effects. We found that implementing reactive vaccination in previous pneumococcal meningitis outbreaks could have averted up to 10-20 % of outbreak cases, with the biggest potential impact in Brong Ahafo, Ghana (2015-2016) and Goundi, Chad (2009). The NNV, and hence the value of reactive vaccination, varied greatly. 'Large' (80 + cumulative modelled cases per 100,000 population) and/or 'prolonged' (exceeding a response threshold of 10 suspected cases per 100,000 per week for four weeks or more) outbreaks had NNV estimates under 10,000. For routine infant vaccination with PCV, the estimated NNV ranged from 3,100-5,600 in Burkina Faso and 1,500-2,600 in Ghana. IMPLICATIONS: This analysis provides evidence to inform the design of pneumococcal meningitis outbreak response guidelines. Countries should consider reactive vaccination in each outbreak event, together with maintaining routine infant vaccination as the primary intervention to reduce pneumococcal disease burden and outbreak risk.

Onchocerciasis in the Cameroon-Chad border area after more than 20 years of annual mass ivermectin distribution.

BACKGROUND: The main vectors of onchocerciasis in Africa are Simulium damnosum sensu lato, which transmit the causative agent Onchocerca volvulus. The force of transmission is driven by the vector density, hence influencing the disease prevalence and intensity. Onchocerciasis is currently targeted for elimination using mass drug administration (MDA) of ivermectin, a potent microfilaricide. MDA in Cameroon began in 1987 in the Vina Valley, an endemic cross-border area with Chad, known for high vector densities and precontrol endemicity. Evaluations in 2008-2010 in this area showed ongoing transmission, while border areas in Chad were close to interrupting transmission. This study aimed to evaluate transmission in this area after several rounds of MDA since the last evaluation surveys. METHODS: Black flies were collected by human landing catches at seven border sites in Cameroon, twice a week, from August 2021 to March 2022. A fraction of the flies was dissected for parity assessment and identification of Onchocerca larval stages. The transmission indices were estimated. Black fly larvae were also collected from the breeding sites at the fly catching sites and identified to species level by cytotaxonomy. RESULTS: A total of 14,303 female flies were collected, and 6918 were dissected. Of these, 4421 (64.0%) were parous. The total biting rates were high, reaching up to 16,407 bites/person/study period, and transmission potential (third-stage larvae (L3) from head/all L3) were 367/702, 146/506, 51/55, 20/32, 0/3, 0/0, and 0/0 infective larvae/person, respectively, for Mbere-Tchad, Babidan, Hajam/V5, Gor, Djeing, Touboro, and Koinderi. Infectivity rates (L3 from head) were 16.00, 12.75, 5.15, and 4.07 infective females (L3H)/1000 parous flies for Haijam, Mbere-Tchad, Babidan, and Gor, respectively. These values exceed the World Health Organization (WHO) thresholds of ≤ 20 annual transmission potential (ATP) or < 1 infective female/1000 parous females. The major vectors identified were Simulium damnosum sensu stricto, S. squamosum, and for the first time in the area, S. yahense. CONCLUSIONS: More than 20 years of MDA has not eliminated onchocerciasis in the study area; hence, this area is a potential source of reintroduction of onchocerciasis in Chad and would require alternative treatment strategies. Many factors such as MDA efficiency, effectiveness of ivermectin, and cytospecies composition may be contributing to transmission persistence.

Refugee women's and providers' perceptions of person-centered maternity care: a qualitative study in two refugee camps in Chad.

BACKGROUND: Globally, mistreatment of women during labor and delivery is a common human rights violation. Person-centered maternity care (PCMC), a critical component of quality of care, is respectful and responsive to an individual's needs and preferences. Factors related to poor PCMC are often exacerbated in humanitarian settings. METHODS: We conducted a qualitative study to understand Sudanese refugee women's experiences, including their perceptions of quality of care, during labor and delivery at the maternities in two refugee camps in eastern Chad, as well as maternity health workers' perceptions of PCMC and how they could be better supported to provide this. In-depth interviews were conducted individually with 22 women who delivered in the camp maternities and five trained midwives working in the two maternities; and in six dyads with a total of 11 Sudanese refugee traditional birth attendants and one assistant midwife. In addition, facility assessments were conducted at each maternity to determine their capacity to provide PCMC. RESULTS: Overall, women reported positive experiences in the camp maternities during labor and delivery. Providers overwhelmingly defined respectful care as patient-centered and respect as being something fundamental to their role as health workers. While very few reported incidents of disrespect between providers and patients in the maternity, resource constraints, including overwork of the providers and overcrowding, resulted in some women feeling neglected. CONCLUSIONS: Despite providers' commitment to offering person-centered care and women's generally positive experiences in this study, one of few that explored PCMC in a refugee camp, conflict and displacement exacerbates the conditions that contribute to mistreatment during labor and delivery. Good PCMC requires organizational emphasis and support, including adequate working conditions and ensuring suitable resources so health workers can effectively perform.

Prevalence of hepatitis B virus infection and its associated factors among students in N'Djamena, Chad.

INTRODUCTION: Infection by hepatitis B virus (HBV) is a major issue in public health. The prevalence of HBV in Chad is 12.4%, all age groups considered. Here, we aimed to determine the prevalence of HBV and its associated factors among university students in N'Djamena, the country's capital. METHODS: A cross-sectional survey of students at either the University of N'djamena or Emi Koussi University was conducted from 3 to 23 July 2021. All participating students provided signed, informed consent and were included in the study consecutively. Blood samples were collected, and serum tested for hepatitis B surface antigen (HBsAg) using the Determine HBsAg rapid test kit, with confirmation of positive tests on an Abbott Architect i1000SR analyzer. Descriptive analysis and logistic regression were used to determine associations between the outcome variable and independent/covariate variables. RESULTS: A total of 457 students with a median age of 24 years were included across different faculties. The prevalence of HBV infection was 14.87% (68/457). Most students (75%) were aged 25 years or less. Unprotected sex was reported by 64.9% of the students and multiple sexual partners by 53.6%. Furthermore, 45.7% of them reported having no knowledge of hepatitis B. Having an HBsAg-positive mother (AOR: 2.11), having a history of transcutaneous medical procedures (AOR: 2.97) and living with a family (AOR: 4.63) were significantly associated with HBV status. Age ≥26 years appeared as a protective factor (AOR = 0.41). CONCLUSION: Our study detected a high, 14.87% prevalence of HBV infection among students in N'djamena, Chad, and shed light on its associated factors. HBV prevention strategies should include raising awareness among students, making full hepatitis vaccination mandatory before children begin school, promoting mass screening to identify and treat chronic HBV carriers and reduce transmission, and reducing the cost of vaccination.

Potential Impact of a Diagnostic Test for Detecting Prepatent Guinea Worm Infections in Dogs.

Chad has seen a considerable reduction in cases of Guinea worm disease (or dracunculiasis) in domestic dogs in recent years. Tethering of dogs and application of Abate® larvicide to water sources appear to have contributed to this progress, but with 767 reported dog cases in 2021, accelerating elimination of the disease in Chad may require additional tools. We investigate the potential benefits of a hypothetical diagnostic test that could be capable of detecting prepatent infections in dogs. We adapt an agent-based simulation model for forecasting the impact of interventions on guinea worm disease in dogs to examine the interaction of multiple test factors including test accuracy, when the test can detect infection, dog selection, and dog-owner compliance with tethering recommendations. We find that a diagnostic test could be successful if used in conjunction with existing interventions, and elimination can be achieved within 2 years with 80% or higher test sensitivity, 90% or higher specificity, systematic testing of each dog twice per year, and more than 90% long-term tethering compliance when a dog tests positive or a worm is emerging. Because of the long incubation period of Guinea worm disease (10-14 months) and the fact that no treatment exists, the benefits of the test rely on the testing rollout and response of dog owners. If the test could estimate the timing of worm emergence, long-term tethering could be eliminated and infected dogs could be tethered only when the worms are expected, minimizing the related resources (human and financial) to support the intervention.

Malaria infection and predictor factors among Chadian nomads' children.

BACKGROUND: In Chad, malaria remains a significant public health concern, particularly among nomadic populations. Geographical factors and the mobility of human populations have shown to be associated with the diversity of Plasmodium species. The study aims to describe the malaria prevalence among nomadic children and to investigate its associated factors. METHODS: A cross-sectional study was conducted in February and October 2021 among nomadic communities in Chad. Blood sample were collected and tested from 187 Arab, Fulani and Dazagada nomadic children aged 3-59 months using malaria rapid diagnostic test (RDT). A structured electronic questionnaire was administered to their parents to collect information about the socio­economic data. Malaria testing results were categorized according to the SD BIOLINE Malaria Ag Pf/Pan RDT procedures. Logistic regression analysis was used to determine key risk factors explaining the prevalence of malaria. STATA version IC 13 was used for statistical analysis. RESULTS: The overall malaria prevalence in nomadic children was 24.60%, with 65.20% being Plasmodium falciparum species and 34.8% mixed species. Boys were twice as likely (COR = 1.83; 95% CI, 0.92-3.62; p = 0.083) to have malaria than girls. Children whose parents used to seek traditional drugs were five times more likely (AOR = 5.59; 95% CI, 1.40-22.30, p = 0.015) to have malaria than children whose parents used to seek health facilities. Children whose parents reported spending the last night under a mosquito net were one-fifth as likely (AOR = 0.17; 95% CI, 0.03-0.90, p = 0.037) to have malaria compared to children whose parents did not used a mosquito net. Furthermore, Daza children were seventeen times (1/0.06) less likely (AOR = 0.06; 95% CI, 0.01-0.70, p = 0.024) to have malaria than Fulani children and children from households piped water as the main source were seven times more likely (AOR = 7.05; 95% CI, 1.69-29.45; p = 0.007) to have malaria than those using surface water. CONCLUSIONS: Malaria remains a significant public health issue in the nomadic communities of Chad. Community education and sensitization programs within nomad communities are recommended to raise awareness about malaria transmission and control methods, particularly among those living in remote rural areas. The National Malaria Control Program (NMCP) should increase both the coverage and use of long-lasting insecticidal nets (LLINs) and seasonal malaria chemoprevention (SMC) in addition to promoting treatment-seeking behaviors in nomadic communities.

Community-based symptom reporting among agro-pastoralists and their livestock in Chad in a One Health approach.

One Health Syndromic Surveillance has a high potential for detecting early epidemiological events in remote and hard-to-reach populations. Chadian pastoralists living close to their animals and being socio-economically unprivileged have an increased risk for zoonosis exposure. Engaging communities in disease surveillance could also strengthen preparedness capacities for outbreaks in rural Chad. This study describes a retrospective cross-sectional survey that collected data on clinical symptoms reported in people and livestock in Chadian agro-pastoral communities. In January-February 2018, interviews were conducted in rural households living in nomadic camps or settled villages in the Yao and Danamadji health districts. The questionnaire covered demographic data and symptoms reported in humans and animals for the hot, wet, and cold seasons over the last 12 months. Incidence rates of human and animal symptoms were comparatively analyzed at the household level. Ninety-two households with a homogeneous socio-demographic distribution were included. We observed cough and diarrhea as the most frequent symptoms reported simultaneously in humans and animals. In all species, the incidence rate of cough was significantly higher during the cold season, and diarrhea tended to occur more frequently during the wet season. However, the incidence rate of cough and diarrhea in animals did not predict the incidence rate of these symptoms in humans. Overall, the variations in reported symptoms were consistent with known seasonal, regional, and sociological influences on endemic diseases. Our retrospective study demonstrated the feasibility of collecting relevant health data in humans and animals in remote regions with low access to health services by actively involving community members. This encourages establishing real-time community-based syndromic surveillance in areas such as rural Chad.

Limited impact of vector control on the population genetic structure of Glossina fuscipes fuscipes from the sleeping sickness focus of Maro, Chad.

Tsetse flies (genus Glossina) transmit deadly trypanosomes to human populations and domestic animals in sub-Saharan Africa. Some foci of Human African Trypanosomiasis due to Trypanosoma brucei gambiense (g-HAT) persist in southern Chad, where a program of tsetse control was implemented against the local vector Glossina fuscipes fuscipes in 2018 in Maro. We analyzed the population genetics of G. f. fuscipes from the Maro focus before control (T0), one year (T1), and 18 months (T2) after the beginning of control efforts. Most flies captured displayed a local genetic profile (local survivors), but a few flies displayed outlier genotypes. Moreover, disturbance of isolation by distance signature (increase of genetic distance with geographic distance) and effective population size estimates, absence of any genetic signature of a bottleneck, and an increase of genetic diversity between T0 and T2 strongly suggest gene flows from various origins, and a limited impact of the vector control efforts on this tsetse population. Continuous control and surveillance of g-HAT transmission is thus recommended in Maro. Particular attention will need to be paid to the border with the Central African Republic, a country where the entomological and epidemiological status of g-HAT is unknown.

Title: Impact limité de la lutte antivectorielle sur la structure des populations de Glossina fuscipes fuscipes dans le foyer de la maladie du sommeil de Maro, Tchad. Abstract: Les mouches tsé-tsé (genre Glossina) transmettent des trypanosomes mortels aux populations humaines ainsi qu'aux animaux domestiques en Afrique sub-saharienne. Certains foyers de la trypanosomiase humaine Africaine due à Trypanosoma brucei gambiense (THA-g) persistent au sud du Tchad, où un programme de lutte antivectorielle a été mis en place contre le vecteur local de la maladie, Glossina fuscipes fuscipes, en particulier à Maro en 2018. Nous avons analysé la structure génétique des populations de G. f. fuscipes de ce foyer à T0 (avant lutte), une année après le début de la lutte (T1), et 18 mois après (T2). La plupart des mouches capturées après le début de la lutte ont montré un profil génétique local (survivants locaux), mais quelques-unes d'entre elles présentaient des génotypes d'individus atypiques. Par ailleurs, la présence de perturbations des signatures d'isolement par la distance (augmentation de la distance génétique avec la distance géographique), l'absence de signature génétique d'un goulot d'étranglement, et un accroissement de la diversité génétique entre T0 et T2 sont des arguments forts en faveur de la recolonisation de la zone par des mouches d'origines variées, tout en témoignant des effets limités de la campagne de lutte dans ce foyer. Ces résultats conduisent à recommander une lutte et une surveillance continues dans le foyer de Maro. Une attention particulière devra par ailleurs être prêtée à l'autre côté de la rive, située côté République Centre Africaine, dont le statut épidémiologique reste inconnu concernant les tsé-tsé et la THA-g.

Assessment of current water, sanitation, and hygiene (WASH) practices in the third and ninth districts of N'Djamena, Chad.

Access to safe drinking water, sanitation, and hygiene in Chad's cities, especially N'Djamena, is a persistent and significant challenge. This study aimed to assess current practices in water, sanitation, and hygiene in N'Djamena's third and ninth districts. We surveyed 395 households, conducted water source identification, and analyzed seven water samples at the National Water Laboratory. Temperature, ammonium, total coliforms, and aerobic flora values exceeded World Health Organization (WHO) guidelines. Ammonium and temperature averaged 0.7 mg/L and 30.1-31.93 °C, respectively. Bacterial contamination (>100 MPN/100 mL) exceeded the WHO's 0 MPN/100 mL guidelines, rendering the water unfit for consumption. Survey results indicate that 78.7% use hand pumps, 21.1% have tap water access, and 0.2% rely on rivers for water. Regarding toilets, 92.8% have traditional models, 2.9% have modern facilities, and 4.3% practice open defecation. 95% dispose of untreated wastewater into nature, with only 5% using septic tanks. For solid waste, 72% use illegal dumpsites, 18% rely on public services, and 10% burn waste. Finally, 95.5% of households wash their hands with clean water and soap after using the toilet. It is crucial to treat drinking water and implement proper hygiene and sanitation measures to safeguard the population's health in the studied area.

Presence of neutralizing SARS-CoV-2 antibodies in asymptomatic population of N'Djamena, Chad.

INTRODUCTION: Neutralizing antibodies (NAbs) are an important specific defence against viral infections, as these antibodies bind to specific receptor(s) and block the viral entry. NAbs assessments are therefore useful in determining individual or herd immunity to SARS-CoV-2. This study aims to deepen the investigation by assessing the positivity rate of neutralizing anti-spike antibodies to understand the real protection of the studied population against SARS-CoV-2. METHODS: This study involved 260 plasma samples from a larger cohort of 2,700 asymptomatic volunteer donors, enrolled between August and October 2021 in health facilities of N'Djamena. In this study four different kits and techniques including the pseudotype assay have been used and compared with detect the SARS-CoV-2 antibodies. Pseudotyped vesicular stomatitis virus (VSV), was used both the identify and measure the NAbs that to evaluate the performance of two cheaper and easy to use commercial kits, specific for the detection of receptor-binding domain antibodies (anti-RBD) against the SARS-CoV-2 spike protein. RESULTS: The VSV spike neutralization assay showed that 59.0% (n = 59) samples were positive for NAbs with titers ranging from 1:10 to 1:4800. While 23 out the 41 negative NAbs samples were detected positive using anti-RBD (Abbott) test. Furthermore, a direct and significant strong correlation was found between NAbs and anti-RBD, specifically with Abbott kit. Taken together, the Roche and Abbott methods indicated agreement at the high concentrations of antibodies with the VSV-pseudovirus method. Abbott and Roche indicated a good sensitivity, but the Abbott system test appeared to have better specificity than the Roche test. CONCLUSION: Our findings indicated a high presence of NAbs against SARS-CoV-2 spike protein among asymptomatic individuals in N'Djamena. This could be one of the reasons for the low severity of Covid-19 observed in this area, given the key role of NAbs in blocking SARS-CoV-2 infection.

Contextual factors for understanding the heterogeneity of outcomes of a policy of exemption from payment for care in Chad / Les facteurs contextuels pour comprendre l'hétérogénéité des résultats d'une politique d'exemption du paiement des soins au Tchad

Chad has one of the highest maternal and infant mortality rates in the world. Efforts to reduce these rates have led to the introduction of fee exemption and community involvement initiatives to further encourage the use of health services. Despite the introduction of these initiatives, inequalities in access to and use of health facilities persist. The aim of this study is to understand why and how the same action, implemented in a quasi-homogeneous way, produced contrasting results in different health centers. A multiple, contrasting case study was used to analyze the outcomes of pediatrics consultations and deliveries in four health centers in the Bénoye and Beinamar districts. Data were collected through individual interviews (n=26) and focus groups (n=22) with women beneficiaries, community health workers, and health care providers. The qualitative software QDA Miner was used to process the data. The study revealed that the organizational and managerial capacities of the providers and community actors would explain the heterogeneity of the results observed. Contextual factors such as the remoteness of services or the impassability and dangerousness of roads accentuated the disparities in the results observed. The results of this study show that human and contextual factors would explain the heterogeneity of the observed effects.

Le Tchad a l'un des taux de mortalité maternelle et infantile les plus élevés au monde. Les efforts visant à réduire ces taux ont conduit à la mise en place d'une politique d'exemption du paiement des soins, associée à l'implication des communautés pour encourager l'utilisation des services. Malgré l'introduction de cette initiative, des inégalités dans l'accès et l'utilisation des établissements de santé persistent. L'objectif de cette étude est de comprendre pourquoi et comment cette politique d'exemption, mise en œuvre de manière quasi homogène, a donné des résultats contrastés dans plusieurs centres de santé. Une étude de cas multiples contrastés a été utilisée pour analyser les résultats des consultations pédiatriques et des accouchements dans quatre centres de santé des districts de Bénoye et Beinamar. Les données ont été recueillies lors des entretiens individuels (n=26) et des groupes de discussion (n=22) auprès des femmes bénéficiaires, des agents de santé communautaire et des prestataires de soins. Le logiciel QDA Miner a été utilisé pour traiter les données. L'étude a révélé que les capacités organisationnelles et managériales des prestataires et des acteurs communautaires expliqueraient l'hétérogénéité des résultats observés. Des facteurs contextuels tels que l'éloignement des services ou l'impraticabilité et la dangerosité des routes ont accentué les disparités des résultats observés. Dans la mise en place des politiques de santé, il est important de tenir compte des facteurs humains et contextuels, car ils participent à l'explication de l'hétérogénéité des effets observés et renforcent la pertinence de ce type d'études.

Predicting the potential impact of scaling up four pneumonia interventions on under-five pneumonia mortality: A prospective Lives Saved Tool (LiST) analysis for Bangladesh, Chad, and Ethiopia.

Background: Pneumonia remains the leading cause of mortality in under-five children outside the neonatal period. Progress has slowed down in the last decade, necessitating increased efforts to scale up effective pneumonia interventions. Methods: We used the Lives Saved Tool (LiST), a modelling software for child mortality in low- and middle-income settings, to prospectively analyse the potential impact of upscaling pneumonia interventions in Bangladesh, Chad, and Ethiopia from 2023 to 2030. We included Haemophilus influenzae type B (Hib) vaccination, pneumococcal conjugate vaccine (PCV), oral antibiotics, pulse oximetry, and oxygen as pneumonia interventions in our analysis. Outcomes of interest were the number of pneumonia deaths averted, the proportion of deaths averted by intervention, and changes in the under-five mortality rate. Findings: We found that 19 775 lives of children under-five could be saved in Bangladesh, 76 470 in Chad, and 97 343 in Ethiopia by scaling intervention coverages to ≥90% by 2030. Our estimated reductions in pneumonia deaths among children under five range from 44.61% to 57.91% in the respective countries. Increased coverage of oral antibiotics, pulse oximetry, and oxygen show similar effects in all three countries, averting between 18.80% and 23.65% of expected pneumonia deaths. Scaling-up PCV has a prominent effect, especially in Chad, where it could avert 14.04% of expected pneumonia deaths. Under-five mortality could be reduced by 1.42 per 1000 live births in Bangladesh, 22.52 per 1000 live births in Chad, and 5.48 per 1000 live births in Ethiopia. Conclusions: This analysis shows the high impact of upscaling pneumonia interventions. The lack of data regarding coverage indicators is a barrier for further research, policy, and implementation, all requiring increased attention.

A Review on Medicinal and Ethnomedicinal Uses, Biological Features, and Phytochemical Constituents of Sesbania sesban L. Merr., A Nitrogen-Fixing Plant Native to the Republic of Chad.

This study reports on a literature review of the leguminous tree Sesbania sesban (L.) Merr which is found in the N'djamena region, the Republic of Chad. The study focused on S. sesban's medicinal and ethnomedicinal uses, biological features, and phytochemical constituents to assist in future evaluations. A literature review was conducted using academic websites, such as Science Direct and Springer, online international plant databases, and data from national herbaria. S. sesban is a perennial shrub or tree that measures 3-4 m in height. This species is becoming rare in N'djamena but can be found in the rainy season, while in winter, it occurs mainly in ponds (called the Chadian dialect "Bouta") and on the shores of the Chari and Logone rivers. The local inhabitants in Chad use the species as medicine, livestock feed, and fuelwood and for improving soil fertility and repelling desert encroachment. Traditional healers use its leaves to treat breast cancer and edema. S. sesban is an essential species native to the Republic of Chad that needs conservation and valorization. Viewing its importance and rarity in N'djamena , a strategy for replanting the species in gardens, homes, and fields around N'djamena and other regions of Chad is recommended.

Epidemiology of group A rotavirus in children under five years of age with gastroenteritis in N'Djamena, Chad.

BACKGROUND: Group A Rotaviruses (RVA) is one of the most common causes of severe diarrhoea in infants and children under 5 years of age. Unlike many countries in the world where RVA surveillance/control is active, in Chad , there is currently no applied RVA immunization program and surveillance strategy. The present study aims to determine the prevalence and associated risk factors of RVA gastroenteritis among children under five years of age in N'Djamena. METHOD: This study comprised two parts: (1) A cross-sectional study carried in four hospitals in N'Djamena between August and November 2019, to determine infection risk factors and evidence of RVA infection among children aged five and below, consulted or hospitalized for diarrhea. An ELISA based RVA VP6 protein detection was used to determine RVA infection prevalence. Infection results and sociodemographic data were statistically analysed to determine RVA infection risk factors. (2) A retrospective study that consisted of analysing the records of stool examinations of the period from January 2016 to December 2018, to determine the prevalence of infectious gastroenteritis among the target population. RESULTS: For the cross-sectional study, RVA infection prevalence was 12.76% (18/141) with males (61.11%) being more affected (sex ratio: 1.57). Children below 12 months were the most affected age group (44.44%) and 44.4% were malnourished. The mean Vesikari score shows that 38.8% of children have a high severity level and 41.1% have a moderate level. For the retrospective study, 2,592 cases of gastroenteritis hospitalization were analysed; 980 out of 2,592 cases (37.81%) of hospitalization due to diarrhoea were due to diarrhoeagenic pathogens including Emtamoeba hystolitica, Gardia lamblia, Trichomonas hominis, Hymenolepis nana, Escherichia coli, Shigella spp, Proteus mirabilis, and Klebsiella oxytoca. Cases of diarrhoea with negative pathogen search were 1,612 cases (62.19%). The diarrhoea peak was observed during the dry seasons, and the age group under 11 months was the most affected was (57.3%). CONCLUSION: This study describes the evidence of RVA infection among diarrhoeic children below five years of age in N'Djamena, thus indicates a serious health burden. Malnourishment younger age was the higher risk factor. Further studies are needed to determine the circulating strains prior to considering introduction of RVA vaccine and setup a routine rotavirus surveillance in Chad.