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.

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.

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.

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.

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.

Impact of COVID-19 Pandemic on the Clinical Follow-Up of Patients Living with HIV in Chad: A Retrospective Monocentric Investigation.

The impact of the coronavirus disease 2019 (COVID-19) pandemic on the clinical follow-up of people living with HIV (PLWH) remains poorly documented in Sahelian Africa. We conducted a monocentric retrospective investigation of the outcomes (loss to follow-up [LTFU], transferred, or dead) among a cohort of PLWH receiving antiretroviral treatment (ART) in N'djamena, Chad (December 2019-December 2022). The incidence of LTFU was found to be higher in 2020 than in 2022 (P > 10-4), with increases of incidence of LTFU in the first trimester of 2020 before identified severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection cases in Chad. The all-cause mortality was low and did not appear to be influenced by SARS-CoV-2 infection waves. Our data reveal a concerning trend of significantly increased LTFU among PLWH receiving ART during the COVID-19 pandemic. Our findings indicate that it is crucial to provide accurate information to ensure the continuity of care for PLWH during a sanitary crisis in Sahelian Africa.

Women's autonomy and fertility in Chad.

Chad's total fertility rate (TFR) is 6.4 children per woman, compared with no more than 5.5 in neighbouring countries: Cameroon and the Central African Republic. Scientific research on the determinants of fertility in Chad should therefore be carried out in order to show decision-makers how they can strengthen their actions in this area. This is the aim of this study, which focuses on the influence of women's autonomy on fertility in Chad. Analyses of data from the Multiple Indicator and Demographic and Health Survey (DHS/MICS) conducted in Chad in 2014/2015 and a qualitative survey conducted in the same country in 2020 show, among other things, that 1) in socio-cultural groups characterised by strong gender inequalities, women's autonomy is positively associated with their desired fertility; 2) in these and other groups characterised by less gender inequality, women's autonomy is negatively associated with their actual fertility, all things being equal; 3) the hypotheses explaining this relationship differ across sociocultural groups: In highly gender- inegalitarian groups, the frequent death of children leads couples in which women have either little or no autonomy to compensate with high fertility, whereas in less gender- inegalitarian groups, the negative association between women's autonomy and fertility is due to late union formation, union dissolution, the fertility-reducing effects of breastfeeding and modern contraception, and other intermediate fertility variables not considered here. These findings highlight both the importance of designing development programmes in Chad that focus on women's empowerment and the need for such programmes to take sufficient account of the socio-cultural contexts in which the populations concerned live.

Au Tchad, l'Indice Synthétique de Fécondité (ISF) est de 6,4 enfants par femme, alors que chez ses voisins, comme le Cameroun et la RCA, il ne dépasse pas 5,5. Il est alors très important de réaliser des recherches scientifiques sur les déterminants de la fécondité dans le premier pays, afin de montrer à ses décideurs comment ils devraient renforcer leurs actions dans ce domaine. La recherche réalisée ici en est un exemple et porte spécifiquement sur l'influence de l'autonomie de la femme sur sa fécondité dans ce pays. Les analyses des données de l'Enquête Démographique et de Santé et à Indicateurs Multiples (EDS/MICS) qui y a été menée en 2014/2015, et de celles de l'enquête qualitative, menée dans le même pays en 2020, ont, entre autres, révélé, ce qui suit : 1) dans les groupes socioculturels très inégalitaires en matière de genre, l'autonomie de la femme est positivement associée à sa fécondité désirée ; 2) dans ces groupes et dans ceux moins inégalitaires, toutes choses égales par ailleurs, l'autonomie de la femme est associée négativement à sa fécondité effective ; 3) les hypothèses d'explication de cette relation varie selon les groupes socioculturels : dans les premiers, les décès fréquents d'enfants entraînent les couples où les femmes ont une autonomie nulle ou faible à les compenser par une fécondité élevée ; dans les derniers, ce sont les entrées tardives en union, les ruptures d'unions, les effets réducteurs d'allaitement et de la contraception moderne et d'autres variables intermédiaires de la fécondité, non prises en compte, qui justifient pourquoi l'autonomie de la femme y est négativement associée à sa fécondité. Les résultats de cette étude témoignent non seulement de la pertinence des programmes de développement focalisés dans ce pays sur l'autonomisation de la femme, mais aussi du fait que pour être efficaces ces programmes devraient prendre suffisamment en compte les contextes dans lesquels vivent les populations concernées.

Community Clustering of Food Insecurity and Malnutrition Associated With Systemic Drivers in Chad.

BACKGROUND: Chad suffers from protracted hunger, facing high food insecurity (Integrated Food Security Phase Classification 3 and above), and acute malnutrition levels that surpass the emergency threshold (15% global acute malnutrition) yearly. The Food Security Sector, with European Union support, leads an inclusive effort to increase synergy between humanitarian, development, and peace-building actors to understand and address drivers of hunger. OBJECTIVE: To understand the spatial distribution of child wasting and household food insecurity and systemic drivers (conflict, livelihoods, vegetation, cultural norms) as well as better understand the relationship between child wasting and household food insecurity in Kanem and Bahr el Ghazal (BeG) region, Chad, with the goal of improving nexus programming and targeting. METHODS: A cross-sectional randomized cluster survey was conducted in August 2021 in Kanem and BeG across 86 villages, reaching 7002 households and 6136 children. Data were collected on child anthropometry, household food security, and livelihoods. Using mixed methods, primary data were triangulated with secondary geospatial data on vegetation index and conflicts as well as qualitative interviews with local actors. Analysis was conducted using comparison tests, linear and logistic crude, and adjusted models, as well as looking at the design effect as a measure of clustering of outcomes at the community level. RESULTS: The geospatial distribution of hunger indicators shows child wasting and food insecurity are highly clustered. However, communities with a high prevalence of child wasting were not those with the highest levels of food insecurity, indicating different pathways. Clustering of food insecurity and child wasting is due to basic drivers of conflict, health, and seasonal access to natural resources. CONCLUSIONS: The high levels of food insecurity and child wasting are each concentrated in specific survey clusters and are not necessarily connected. They result from different causal pathways at the community level linked to the systemic drivers of the rule of access to natural resources, environmental seasonality, and livelihoods. This suggests a greater need for an integrated humanitarian, development, and peace-building interventions to address the persistent high prevalence of food insecurity and child wasting. It also suggests that these community-level and systemic drivers require greater consideration from the start in research design and data collection.

Plain language titleUnderstanding Linkages Between Household Food Insecurity, Child Malnutrition, and Their Respective Clustered Drivers in ChadPlain language summaryChad experiences emergency levels of household food insecurity and child malnutrition. To address this issue, the United Nations Food and Agricultural Organization has undertaken a collaborative effort to enhance cooperation among humanitarian, development, and peace-building actors. The objective of this study was to examine how child malnutrition, food insecurity, and their drivers cluster across communities in Kanem and Bahr El Ghazal to improve response planning and targeting. The study collected data in August 2021 on malnutrition, food security, livelihoods, vegetation, and conflict and carried out interviews with local informants. In total, the research covers 86 villages, 7,002 households, and 6,136 children. The research shows that the 2 measures of hunger, child malnutrition and food insecurity, are highly clustered, affecting some communities more than others. However, villages with a high prevalence of child acute malnutrition did not have the highest levels of food insecurity, suggesting different community-level drivers. The clustering of food insecurity and malnutrition at the village level was linked to the diversity of livelihoods, the experience of conflict, health, and seasonal limitations in accessing natural resources. These findings are crucial for informing the targeting and design of integrated humanitarian, development, and peace programs. Taking a systemic approach and fostering strong coordination across interventions to address the drivers of food insecurity and malnutrition holds great potential for tackling hunger in Chad.

The Complexity of the Seasonality of Nutritional Status: Two Annul Peaks in Child Wasting in Eastern Chad.

BACKGROUND: Understanding seasonal patterns in nutritional status is critical for achieving and tracking global nutrition goals. However, the majority of nutrition seasonality research design draws on 2 or 3 within-year time points based on existing assumptions of seasonality, missing a more nuanced pattern. OBJECTIVE: We aimed to identify the intra-year variability of childhood wasting, severe wasting, and weight-for-height z-scores (WHZ) in a dryland single wet-season context and illustrate an analytical approach for improving analysis of the seasonality of nutritional status. METHODS: To quantify the intra-year variability in nutritional status, we use data from a 23-month panel study (May 2018 to March 2020) following 231 children (6-59 months of age) in eastern Chad. We apply a mixed-effects harmonic regression with child- and village-level fixed effects on the odds of being wasted, severely wasted, and on WHZ, testing for multiple and nonsymmetrical seasonal peaks, adjusted for child sex and age. We triangulate our findings using climate data on temperature, vegetation, and precipitation. RESULTS: We identify 2 annual peaks of wasting and severe wasting. Wasting peaks at 14.7% (confidence interval [CI], 11.8-18.2) at the end of the dry season, while the smaller peak corresponds to the start of the harvest period at 13.4% (CI, 10.7-16.6). The odds of being wasted decline during the rainy season to 11.8% (CI, 9.4-14.7), with the lowest prevalence of 8.8% (CI, 6.9-11.1) occurring during the start of the dry season. In addition, a 1°C monthly increase in temperature is significantly associated with a 5% (CI, 1.4-8.7) and 12% (CI, 3.0-20.3) increase in the odds that a child is wasted and severely wasted, respectively. CONCLUSIONS: Intra-year variability of child wasting is far more complex and nuanced than identified by the literature, with 2 peaks, as opposed to 1, likely corresponding to different seasonal drivers, such as food insecurity, disease, water contamination, and care practices at different times of year. Better seasonality analysis can go a long way in improving the timing and content of programming with the goal of reducing child wasting.

Plain language titleTwo Seasonal Peaks of Acute Malnutrition in ChadPlain language summaryUnderstanding seasonal patterns in nutrition is crucial for achieving and monitoring global nutrition goals. However, most research on nutrition seasonality relies on only a few time points within a year, which oversimplifies the true pattern. In our study conducted in Chad, a dryland environment with a single rainy season, we examined various indicators of acute malnutrition, including severe acute malnutrition. We analyzed 23 months of data from 231 children aged 6 to 59 months, considering factors such as sex, age, monthly rainfall, temperature, and vegetation. Our findings revealed 2 peaks of acute malnutrition, challenging the prevailing notion of a single peak identified in existing literature. The first, larger peak occurred at the onset of the rainy season, followed by a decline and then a second peak just before the harvest period. This pattern aligned with temperature variations rather than rainfall. The complex and nuanced seasonal patterns we observed suggest that different factors such as food insecurity, disease, water contamination, and care practices may contribute to acute malnutrition at different times of the year. Improved analysis of seasonality can significantly enhance the timing and effectiveness of interventions aimed at reducing child wasting.

Trends and Determinants of Children's Wasting and Women's Thinness in Chad, 2015 to 2021.

BACKGROUND: Cross-sectional surveys using the Standardized Monitoring and Assessment of Relief and Transitions methodology have been conducted annually in Chad since 2015 to evaluate population-level nutritional status. OBJECTIVE: This analysis characterizes national and subnational trends in child wasting and women's thinness from 2015 to 2021 in Chad and identifies risk factors during the COVID-19 pandemic. METHODS: Annual survey data with 12,000 to 15,000 households were included. Wasting was estimated for children 6 to 59 months using the WHO child growth standards, and among women 15 to 49 years, thinness was defined as mid-upper arm circumference <23 cm. Trends were stratified by agroecological zone, and chi-square tests used to assess statistical significance. Simple and multivariate logistic regression models were conducted for 2020 and 2021 to identify risk factors of wasting and thinness. RESULTS: About 11,958 to 17,897 children and 9883 to 15,535 women contributed values each year. National wasting and thinness rates did not significantly decrease over the 7-year period (wasting: 14.1% to 12.1%, P = .43; thinness: 15.2% to 13.4%, P = .51) and wasting rose from 2020 to 2021. The Saharan and Sahelian zones had consistently higher rates compared to the Sudanian zone. Younger age, male sex, inadequate infant and young child feeding practices, and poorer household socio-economic factors were associated with greater odds of child wasting. For women, younger age, lack of nutrition knowledge, and poorer household socio-economic factors increased the odds of thinness. CONCLUSIONS: Undernutrition in Chad has not improved since 2015, and the COVID-19 pandemic likely exacerbated the crisis among children nationally and among women subnationally. Multisectoral approaches and regional targeting of interventions are recommended.

Health economic evaluation of strategies to eliminate gambiense human African trypanosomiasis in the Mandoul disease focus of Chad.

Human African trypanosomiasis, caused by the gambiense subspecies of Trypanosoma brucei (gHAT), is a deadly parasitic disease transmitted by tsetse. Partners worldwide have stepped up efforts to eliminate the disease, and the Chadian government has focused on the previously high-prevalence setting of Mandoul. In this study, we evaluate the economic efficiency of the intensified strategy that was put in place in 2014 aimed at interrupting the transmission of gHAT, and we make recommendations on the best way forward based on both epidemiological projections and cost-effectiveness. In our analysis, we use a dynamic transmission model fit to epidemiological data from Mandoul to evaluate the cost-effectiveness of combinations of active screening, improved passive screening (defined as an expansion of the number of health posts capable of screening for gHAT), and vector control activities (the deployment of Tiny Targets to control the tsetse vector). For cost-effectiveness analyses, our primary outcome is disease burden, denominated in disability-adjusted life-years (DALYs), and costs, denominated in 2020 US$. Although active and passive screening have enabled more rapid diagnosis and accessible treatment in Mandoul, the addition of vector control provided good value-for-money (at less than $750/DALY averted) which substantially increased the probability of reaching the 2030 elimination target for gHAT as set by the World Health Organization. Our transmission modelling and economic evaluation suggest that the gains that have been made could be maintained by passive screening. Our analysis speaks to comparative efficiency, and it does not take into account all possible considerations; for instance, any cessation of ongoing active screening should first consider that substantial surveillance activities will be critical to verify the elimination of transmission and to protect against the possible importation of infection from neighbouring endemic foci.

Diversity of trypanosome species in small ruminants, dogs and pigs from three sleeping sickness foci of the south of Chad.

Despite considerable data generated on livestock trypanosomoses in tsetse-infested areas, little attention was paid for animal African trypanosomosis (AAT) in sleeping sickness foci. This study aimed to fill this gap by determining the diversity and prevalence of trypanosome species in animals from three Chadian human African trypanosomosis (HAT) foci. Blood samples were collected from 443 goats, 339 sheep, 228 dogs and 98 pigs of the Mandoul, Maro and Moissala HAT foci in the south of Chad. Capillary tube centrifugation (CTC) and specific primers were used to search trypanosomes. The prevalence of trypanosome infections was 6.3% for CTC and 22.7% for PCR. Trypanosomes of the sub-genus Trypanozoon had the highest prevalence (16.6%) while T. congolense savannah (1.9%) was least prevalent. Significant differences were recorded between the prevalence of trypanosome species (χ2 = 8.34; p = 0.04) and HAT foci (χ2 = 24.86; p ≤0.0001). Maro had the highest prevalence (32.7%) and Mandoul the lowest (17.4%). Significant differences were also recorded for T. congolense forest (χ2 = 45.106; p < 0.0001) and all T. congolense (χ2 = 34.992; p < 0.0001). Goats had the highest prevalence (26.9%) and sheep the lowest one (18.6%). Between animals, significant differences were recorded for trypanosomes of the sub-genus Trypanozoon (χ2 = 9.443; p = 0.024), T. congolense forest (χ2 = 10.476; p = 0.015) and all T. congolense (χ2 = 12.152; p = 0.007). Of the 251 animals carrying trypanosome infections, 88.8% had single infections while 11.2% had more than one trypanosome species. The overall prevalence of single and mixed trypanosome infections were respectively 20.1% and 2.6% in animal taxa of all foci. This study highlighted a diversity of trypanosomes in animal taxa of all HAT foci. It showed that AAT constitutes a threat for animal health and animal breeding in Chadian HAT foci. In these tsetse infested areas, reaching the elimination of AAT requires the designing and the implementation of control measures against trypanosome infections.

Seroprevalence and associated risk factors of brucellosis, Rift Valley fever and Q fever among settled and mobile agro-pastoralist communities and their livestock in Chad.

Brucellosis, Rift Valley fever (RVF) and Q fever are zoonoses prevalent in many developing countries, causing a high burden on human and animal health. Only a few studies are available on these among agro-pastoralist communities and their livestock in Chad. The objective of our study was to estimate brucellosis, RVF and Q fever seroprevalence among Chadian agro-pastoralist communities and their livestock, and to investigate risk factors for seropositivity. We conducted a multi-stage cross-sectional serological survey in two rural health districts, Yao and Danamadji (966 human and 1041 livestock (cattle, sheep, goat and equine) samples)). The true seroprevalence were calculated applying a Bayesian framework to adjust for imperfect diagnostic test characteristics and accounting for clustering in the study design. Risk factors for each of the zoonotic diseases were estimated using mixed effects logistic regression models. The overall prevalence for brucellosis, Q fever and RVF combined for both regions was estimated at 0.2% [95% credibility Interval: 0-1.1], 49.1% [%CI: 38.9-58.8] and 28.1% [%CI: 23.4-33.3] in humans, and 0.3% [%CI: 0-1.5], 12.8% [%CI: 9.7-16.4] and 10.2% [%CI: 7.6-13.4] in animals. Risk factors correlating significantly with the respective disease seropositivity were sex for human brucellosis, sex and Q fever co-infection for animal brucellosis, age for human Q fever, species and brucellosis co-infection for animal Q fever, age and herd-level animal RVF seroprevalence within the same cluster for human RVF, and cluster-level human RVF seroprevalence within the same cluster for animal RVF. In Danamadji and Yao, Q fever and RVF are notably seroprevalent among agro-pastoralist human and animal communities, while brucellosis appears to have a low prevalence. Correlation between the seroprevalence between humans and animals living in the same communities was detected for RVF, highlighting the interlinkage of human and animal transmissible diseases and of their health, highlighting the importance of a One Health approach.

[Prevalence of dyslipidemia in the biochemistry laboratory of the Reference National Teaching Hospital of N'Djamena, Chad.] / Prévalence des dyslipidémies au laboratoire de biochimie du CHU la Référence Nationale de N'Djamena/Tchad.

INTRODUCTION: les dyslipidémies constituent un facteur de risque majeur dans la survenue des maladies cardio-vasculaires. La recherche de ce facteur et sa prise en charge adéquate contribuerait à prévenir ces maladies qui sont la plus grande cause de décès dans le monde. L'objectif de cette étude était d'évaluer la prévalence des dyslipidémies au laboratoire de biochimie du Centre Hospitalier Universitaire de Référence Nationale de N'Djamena. MATéRIEL ET MéTHODES: il s'agissait d'une étude transversale d'une durée de cinq ans (2015-2020) portant sur tous les patients ayant au moins un paramètre lipidique dans le registre du laboratoire. Les méthodes enzymatiques sur un automate de biochimie de type Cobas Integra 400 (Roche Diagnostics) ont été utilisées pour le dosage de cholestérol total, LDL-c, HDL-c et de triglycérides. RESULTS: Au total 2038 patients avec une prédominance masculine (sex-ratio :1,33), ont été enregistrés, l'âge moyen de nos patients était de 56,45±8,8 ans. La prévalence des dyslipidémies était de 44,2%. Les différents types des dyslipidémies étaient repartis comme suit : l'hypercholestérolémie (40,52%) ; l'hyper LDLémie (33,02%) ; l'hypoHDLémie (14,72%) ; l%hypertriglyc%rid%mie (11,72%) et l'hyperlipidémie mixte (40,5%). On notait une évolution croissante de la prévalence de dyslipidemie au cours des cinq années de periode d'étude. CONCLUSIONS: la forte prévalence des dyslipidémies dans notre étude témoigne d'une situation préoccupante au Tchad, d'où l'intérêt d'étudier la prévalence des dyslipidémies et des autres facteurs de risque cardiovasculaire à l'échelle nationale et l'utilité d'organiser des campagnes d'éducations et d'informations sur les maladies cardiovasculaires et les facteurs de risque cardiovasculaire afin de r'duire cette pr'valence.

Gini index decomposition by deprivation in multidimensional poverty: evidence from Chad.

OBJECTIVE: This paper aims the decomposition of the multidimensional Gini coefficient by deprivation to investigate how aggregate multidimensional poverty inequality translates into inequality within each of its components. This approach provides a better understanding of the distribution of deprivations held, the standard of living of the population and makes recommendations on government policies. METHOD: We use the method of Lerman and Yitzhaki (1985), which allows us to identify the impact of marginal changes on multidimensional inequality (fuzzy poverty inequality). RESULTS: The data used come from the Household Budget and Consumption Surveys of 2003 of 6695 households, 2011 of 9259 households and 2018 of 7493 households. Empirical findings suggest that the Gini index in 2003 is 0.229, 0.215 in 2011 and 0.180 in 2018. CONCLUSIONS: The different social policies to reduce multi-inequalities must mainly be oriented towards health policies and access to drinking water, which are unequally distributed during the three periods. And social policies to reduce inequality in education, sanitation and housing are also to be taken into account.

Vector competence of sterile male Glossina fuscipes fuscipes for Trypanosoma brucei brucei: implications for the implementation of the sterile insect technique in a sleeping sickness focus in Chad.

BACKGROUND: Human African trypanosomiasis (HAT) is a neglected tropical disease caused by Trypanosoma brucei gambiense transmitted by tsetse flies in sub-Saharan West Africa. In southern Chad the most active and persistent focus is the Mandoul focus, with 98% of the reported human cases, and where African animal trypanosomosis (AAT) is also present. Recently, a control project to eliminate tsetse flies (Glossina fuscipes fuscipes) in this focus using the sterile insect technique (SIT) was initiated. However, the release of large numbers of sterile males of G. f. fuscipes might result in a potential temporary increase in transmission of trypanosomes since male tsetse flies are also able to transmit the parasite. The objective of this work was therefore to experimentally assess the vector competence of sterile males treated with isometamidium for Trypanosoma brucei brucei. METHODS: An experimental infection was set up in the laboratory, mimicking field conditions: the same tsetse species that is present in Mandoul was used. A T. b. brucei strain close to T. b. gambiense was used, and the ability of the sterile male tsetse flies fed on blood with and without a trypanocide to acquire and transmit trypanosomes was measured. RESULTS: Only 2% of the experimentally infected flies developed an immature infection (midgut) while none of the flies developed a metacyclic infection of T. b. brucei in the salivary glands. We did not observe any effect of the trypanocide used (isometamidium chloride at 100 mg/l) on the development of infection in the flies. CONCLUSIONS: Our results indicate that sterile males of the tested strain of G. f. fuscipes were unable to cyclically transmit T. b. brucei and might even be refractory to the infection. The data of the research indicate that the risk of cyclical transmission of T. brucei by sterile male G. f. fuscipes of the strain colonized at IAEA for almost 40 years appears to be small.

Treating osteoarticular infections in a Role 2 in Chad: a bacterial epidemiological study.

INTRODUCTION: The treatment of osteoarticular infections in Africa is a medical and surgical challenge due to the difficulties in managing antibiotic therapy after the surgical procedure. The objectives of this study were to identify the types of bacteria in osteoarticular lesions in patients treated in Chad and to determine the spectrum of resistance encountered and the efficacy of available antibiotics. MATERIAL AND METHODS: This is a retrospective study of all intraoperative osteoarticular and soft tissue samples taken in a French Role 2 Medical Treatment Facility of N'Djamena during surgery for chronic osteoarticular infections, in Chad, for 1 year. RESULTS: A total of 160 bacterial strains were identified, with a predominance of Gram-negative bacillus (GNB) and staphylococcus infections. Among staphylococci, 80% were methicillin-sensitive streptococci which were generally multidrug-sensitive. Enterococci were resistant to third-generation cephalosporins, first-generation fluoroquinolones and gentamycin. Among GNB, there was a predominance of enterobacteria compared with non-fermenting GNB, of which 52% were multidrug-resistant and produced extended spectrum beta-lactamases (ESBL). CONCLUSION: Staphylococcus aureus infections are most often sensitive to available antibiotics and therefore have better prognoses than infections caused by other bacteria. In contrast, in half of the cases of GNB, infections were caused by bacteria producing ESBL, thus posing the problem of multidrug-resistance, the risks of which are increased in precarious situations. Therefore, the type of bacteria appears to be a major prognostic factor in the treatment of osteoarticular infections in a Role 2 in Chad. This criterion will need to be considered before any treatment decisions are made.

Gini index decomposition by deprivation in multidimensional poverty: evidence from Chad / Descomposición del índice de Gini por privación en la pobreza multidimensional: evidencia de Chad

Objective: This paper aims the decomposition of the multidimensional Gini coefficient by deprivation to investigate how aggregate multidimensional poverty inequality translates into inequality within each of its components. This approach provides a better understanding of the distribution of deprivations held, the standard of living of the population and makes recommendations on government policies. Method: We use the method of Lerman and Yitzhaki (1985), which allows us to identify the impact of marginal changes on multidimensional inequality (fuzzy poverty inequality). Results: The data used come from the Household Budget and Consumption Surveys of 2003 of 6695 households, 2011 of 9259 households and 2018 of 7493 households. Empirical findings suggest that the Gini index in 2003 is 0.229, 0.215 in 2011 and 0.180 in 2018. Conclusions: The different social policies to reduce multi-inequalities must mainly be oriented towards health policies and access to drinking water, which are unequally distributed during the three periods. And social policies to reduce inequality in education, sanitation and housing are also to be taken into account. (AU)

Objetivo: Este trabajo busca la descomposición del coeficiente de Gini multidimensional por privación para investigar cómo la desigualdad de pobreza multidimensional agregada se traduce en desigualdad dentro de cada uno de sus componentes. Este enfoque permite comprender mejor la distribución de las privaciones y el nivel de vida de la población, y formular recomendaciones sobre las políticas gubernamentales. Método: Utilizamos el método de Lerman y Yitzhaki (1985), que permite identificar el impacto de los cambios marginales sobre la desigualdad multidimensional (desigualdad difusa de la pobreza). Resultados: Los datos utilizados provienen de las Encuestas de Presupuesto y Consumo de Hogares de 2003 en 6695 hogares, de 2011 en 9259 hogares y de 2018 en 7493 hogares. Los hallazgos empíricos sugieren que el índice de Gini en 2003 es 0,229, en 2011 es 0,215 y en 2018 es 0,180. Conclusiones: Las diferentes políticas sociales para reducir las desigualdades múltiples deben orientarse principalmente hacia las políticas de salud y acceso al agua potable, que se distribuyen de manera desigual durante los tres periodos. También deben tenerse en cuenta las políticas sociales para reducir la desigualdad en la educación, el saneamiento y la vivienda. (AU)

Prevalence of pathogenic trypanosome species in naturally infected cattle of three sleeping sickness foci of the south of Chad.

Although a diversity of trypanosome species have been detected in various animal taxa from human African trypanosomosis (HAT) foci, cattle trypanosomosis has not been addressed in HAT foci of west and central African countries including Chad. This study aimed to determine the prevalence of pathogenic trypanosome species in cattle from three HAT foci of the south of Chad. Blood samples were collected from 1466 randomly selected cattle from HAT foci of Mandoul, Maro, and Moïssala in the south of Chad. For each animal, the sex, age and body condition were recorded. Rapid diagnostic test (RDT) was used to search Trypanosoma brucei gambiense antibodies while the capillary tube centrifugation (CTC) test and PCR-based methods enabled to detect and identify trypanosome species. From the 1466 cattle, 45 (3.1%) were positive to RDT. The prevalence of trypanosome infections revealed by CTC and PCR-based method were respectively 2.7% and 11.1%. Trypanosomes of the subgenus Trypanozoon were dominant (6.5%) followed by T. congolense savannah (2.9%), T. congolense forest (2.5%) and T. vivax (0.8%). No animal was found with DNA of human infective trypanosome (T. b. gambiense). The overall prevalence of trypanosome infections was significantly higher in animal from the Maro HAT focus (13.8%) than those from Mandoul (11.1%) and Moïssala HAT foci (8.0%). This prevalence was also significantly higher in animal having poor body condition (77.5%) than those with medium (11.2%) and good (0.5%) body condition. The overall prevalence of single and mixed infections were respectively 9.4% and 1.6%. This study revealed natural infections of several pathogenic trypanosome species in cattle from different HAT foci of Chad. It showed similar transmission patterns of these trypanosome species and highlighted the need of developing control strategies for animal African trypanosomosis (AAT) with the overarching goal of improving animal health and the economy of smallholder farmers.