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Cutaneous myiasis caused by various Calliphoridae dipteran species is prevalent worldwide and is of particular veterinary and public health concern. Recently, in a scientific exploration of the Guinea Worm Eradication Program to Chad, Africa, we observed that dogs with mutilated ears, based on local awareness, were caused by cutaneous myiasis. In this study, we analyzed epidemiological, morphological, and molecular data on cutaneous myiasis in dogs from Chad. From September to October 2022, dogs (n = 1,562) from 56 villages situated along the Chari River were physically inspected for cutaneous myiasis. All larvae were collected and identified morphologically and by molecular analysis of the partial cytochrome oxidase c subunit I (COI) mitochondrial gene. The prevalence of myiasis infestation along with 95 % confidence intervals (95 % CI) was determined using the modified Wilson method. Myiasis was detected in dogs from 21 villages (37.5 %; 95 % CI 26 - 50 %), predominating in the southernmost region. Of 1,562 dogs, 66 (4.22 %; 95 % CI 3.34 - 5.34 %) were infested by calliphorid larvae, with a mean infestation of 2.28 larvae per animal (range = 1 to 24). Specimens were morphologically identified as Cordylobia anthropophaga (n = 94), Chrysomya bezziana (n = 54), and Chrysomya sp. (n = 3), which were detected in 57, eight and one dog, respectively. No co-infestations were observed. The molecular analyses confirmed the morphological identification and revealed the presence of 17 haplotypes for C. anthropophaga, 2 for C. bezziana, and one for Chrysomya sp. Our study emphasizes the veterinary importance of myiasis in dogs in Africa and proposes measures to assure their health and well-being., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

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., Competing Interests: Declaration of competing interest None of the authors have competing interests., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Better surveillance is desperately needed to guide rabies prevention and control to achieve the goal of zero dog-mediated human rabies by 2030, defined by the World Health Organization (WHO) and partners in 2015. With the help of funding from the Vaccine Alliance (GAVI) learning agenda, we implemented animal rabies surveillance based on One Health communication, improved accessibility of diagnostic testing and facilitated sample transport to increase case detection in three regions of Chad. Through the project, rabies surveillance, previously only available in N'Djaména, was extended to selected provincial rural and urban areas. Nine decentralized diagnostic units (DDU) were established, hosted by veterinary district agencies (VDA) in four different administrative regions. Four additional VDAs in the study area were reinforced with facilitation of sample collection and transport. Staff from all these 13 veterinary facilities were trained in sample collection and diagnostics. DDUs performed Rapid Immunodiagnostic Tests (RIDT) providing a preliminary result before samples were sent to the central laboratory in N'Djamena for confirmation with the standard Florescent Antibody Test (FAT). Within the project period from June 2016 to March 2018, 115 samples were reported by veterinary facilities in the study areas compared to 63 samples received from outside the study area, the vast majority of them originating from the capital city N'Djaména (N=61). Eighty nine percent of all 178 samples reported to IRED during the project period tested positive. Most of the samples originated from dogs (92%). Other confirmed rabies positive animals observed were cats, a donkey and a pig. Although surveillance of animal rabies was the focus, four human saliva samples were also submitted for diagnosis. We observed high differences in reporting rates between the four study regions. This could be attributable to differences in rabies epidemiology but are also influenced by the distance to the central laboratory in N'Djaména, the cultural background and the level of public awareness. The possibility for local testing through RIDT was very welcomed by local veterinary staff and preliminary insights suggest a positive influence on One Health communication and PEP initiation. However, these aspects as well as the relative impact of local testing on sample collection in comparison to reinforcement of sample collection and transport alone, need to be further investigated. Challenges encountered related to poor infrastructure (buildings, appliances, materials) and low logistic capacity (lacking means and material for transport and communication) of veterinary services in Chad. In addition, veterinary personnel lack experience in data management. Together with staff turnover, this leads to a need for repeated training. Major shortcoming of the approach was the high cost per sample and limited sustainability beyond the project timeframe., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Rabies remains a global public health problem, with Africa as one of the most affected continents. Endemic transmission in the unvaccinated domestic dog population of developing countries leads to many exposures with subsequent death in humans due to lack of access to existing effective prevention tools. The presented study identifies factors of exposure and rabies risk in Chad on the household and health facility levels and highlights the challenges of access to Post Exposure Prophylaxis (PEP). Data on bite exposure and prevention was collected through a representative cross-sectional survey in rural and urban households and through a continuous bite reporting survey in public health facilities. During the household survey 8000 homes were visited, including 3241 (41%) in urban areas and 4759 (59%) in rural areas. The frequency of dog ownership was similar in both rural and urban areas, with around 24% households owning at least one dog. Knowledge of rabies as a disease transmitted mainly from dogs to humans was generally good, but higher in urban (86%) compared to rural areas (73%). The need for early prevention and medical care after a bite was less well known with 35% of respondents believing that rabies is curable after onset of symptoms and only one in three bite victims seeking help in a health facility. Exposure risk based on bite incidence on the population level was increased for Christian compared to Muslim predominant religious context. During the health facility study, 1540 bite cases were registered, of which 58% originated from urban areas and 42% from rural areas. Demographic characteristics of the health facility data subset matched the household survey data subset for the majority of parameters. Only bites from known animals (same household or from neighbourhood) and bites from animals known to be alive were underrepresented, suggesting that such bites are regarded as less dangerous than bites from unknown animals and animals that died, were killed or disappeared. Since human vaccine was provided free of charge during the study, most victims received PEP (84%). However, not all patients completed treatment, with a higher risk of non-compliance observed in rural areas. Access to vaccine before the study was alarmingly low, with only 8.5% accessing PEP. Despite facilitated collaboration between human health and veterinary services through the project, consultation with veterinary services remained generally low. The observed challenges can inform future rabies control programmes on the national level to effectively increase access to PEP exceeding the expected improved availability of human vaccine through the upcoming GAVI investment., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020. Published by Elsevier B.V.)

To prevent human rabies deaths close communication between the veterinary and human health sector is needed for timely and adequate treatment after a bite exposure. Good practice treatment and efficient One Health communication depends heavily on the knowledge and practices (KP) of both human health and veterinary workers. We have evaluated the level of KP of both these sectors during a one-day joint training program to kick start a large scale rabies burden and vaccine demand study in selected regions of Chad. Participants were evaluated through a questionnaire before and after training to get insight into the basic knowledge of rabies and the improvement of this knowledge after the training session. In addition to 20 questions on rabies derived from the educational platform of the Global Alliance for Rabies Control, the questionnaires included a pre-training knowledge self-evaluation and a post-training evaluation of the course. Overall 247 workshop participants with varied level of educational background responded to at least one questionnaire. Around 75% of respondents were from the human health sector and 20% from the veterinary sector. Knowledge level did not differ significantly between the two sectors nor between rural or urban working backgrounds. Respondents with a university degree scored significantly higher in pre-and post-training questionnaire compared to respondents with high school level degree or lower. Knowledge was also dependent on study region and sex of the respondent. In general, the importance of a One Health approaches, such as vaccination of dogs to prevent human rabies, is well understood in both sectors. Regarding treatment, many participants did not know the adequate number of doses required for a full course of PEP, but through the training, this knowledge improved. Detailed knowledge of atypical transmission routes and pathophysiology (neurotropism of the virus) was generally lacking and did not significantly improve through the training. The study revealed considerable deficiencies and challenges in the knowledge level of both veterinary and human health workers in Chad. Rabies control programs need to anticipate these challenges to implementation and provide sufficient time and funds for training workshops and follow-up., Competing Interests: Declaration of Competing Interest None declared., (Copyright © 2019. Published by Elsevier B.V.)

Canine rabies represents a major - but preventable - public health threat in Chad. In preparation for a nation-wide canine parenteral mass vaccination campaign we conducted a community-based, cross-sectional multi-stage cluster survey in 40 villages in two southern and two northern regions of Chad. Our objective was to investigate rabies awareness and dog-ownership among the rural population. Almost half of the households (45%) owned dogs, with an overall dog:human ratio of 1:7.8. Southern households owned almost two thirds (701/918) of all dogs and the number of dogs per household was twice as high compared to the north (2.7 vs. 1.3, respectively). This translates into a dog:human ratio of 1:5.2 in the south and 1:16.4 in the north. Only 76% of the respondents had heard of rabies. Respondents who (1) were male, (2)>19 years, (3) had primary education or higher and (4) were of Muslim faith were more likely to have heard of rabies (p<0.01). High level of rabies knowledge was positively associated with (1) southern residence, (2) any kind of education and (3) Christian or "other" religions. In contrast to rabies awareness, high level of knowledge was negatively associated with increasing age. 11% of respondents reported that at least one family member had been bitten by a dog in the past year and half of these bite victims were children. 31% of respondents knew someone who had died of rabies and twice as many (58%) reported having encountered a rabid animal. Most of the respondents could identify classical rabies symptoms (58-94%), however they lacked knowledge about rabies prevention and appropriate wound management. Only 2 out of 963 (0.5%) reported to have vaccinated their dog. A major proportion of our study population is at great risk of rabies (likely higher than 7 rabies death per million per year) due to lack of awareness of the disease, inappropriate post-bite treatment and insufficient knowledge about preventive measures. This reflects the urgent need for advocacy programs to raise rabies awareness among the community. Close intersectoral collaboration between the public health and veterinary sector and integration of local authorities, is a key element in the fight against rabies., (Copyright © 2016. Published by Elsevier B.V.)

Close to 69,000 humans die of rabies each year, most of them in Africa and Asia. Clinical rabies can be prevented by post-exposure prophylaxis (PEP). However, PEP is commonly not available or not affordable in developing countries. Another strategy besides treating exposed humans is the vaccination of vector species. In developing countries, the main vector is the domestic dog, that, once infected, is a serious threat to humans. After a successful mass vaccination of 70% of the dogs in N'Djaména, we report here a cost-estimate for a national rabies elimination campaign for Chad. In a cross-sectional survey in four rural zones, we established the canine : human ratio at the household level. Based on human census data and the prevailing socio-cultural composition of rural zones of Chad, the total canine population was estimated at 1,205,361 dogs (95% Confidence interval 1,128,008-1,736,774 dogs). Cost data were collected from government sources and the recent canine mass vaccination campaign in N'Djaména. A Monte Carlo simulation was used for the simulation of the average cost and its variability, using probability distributions for dog numbers and cost items. Assuming the vaccination of 100 dogs on average per vaccination post and a duration of one year, the total cost for the vaccination of the national Chadian canine population is estimated at 2,716,359 Euros (95% CI 2,417,353-3,035,081) for one vaccination round. A development impact bond (DIB) organizational structure and cash flow scenario were then developed for the elimination of canine rabies in Chad. Cumulative discounted cost of 28.3 million Euros over ten years would be shared between the government of Chad, private investors and institutional donors as outcome funders. In this way, the risk of the investment could be shared and the necessary investment could be made available upfront - a key element for the elimination of canine rabies in Chad., (Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.)

Vitamin A deficiency is a prevalent public health problem in Africa and South-East Asia, although national population based surveys are lacking in many countries. This study investigated seasonal variation of human retinol concentrations in Chadian mobile pastoralists to identify critical time periods for interventions addressing vitamin A deficiency. The repeated cross-sectional study design used convenience sampling during three seasons to include 327 Fulani, Gorane and Arab adult mobile pastoralists in nine camps in the Lake Chad area. Human blood and pooled cattle milk retinol concentrations were rapidly assessed by portable flourometer (iCheck™). Linear regression models with random effects for correlation within camps were applied with human retinol concentration as outcome. Logistic regression models, with camp as random effect, were evaluated for the outcome human retinol deficiency. Human seasonal means were 2.14μmol/L (95% CI 1.82-2.46) in rainy, 0.99μmol/L (95% CI 0.91-1.07) in cold and 1.86μmol/L (95% CI 1.63-2.09) in dry season. Retinol concentration and deficiency varied according to season and ethnic group. Average values were highest in Gorane during rainy and in Fulani in the cold and dry seasons. Arabs had lowest average values in all seasons. Retinol deficiency (<0.70μmol/L) was found in 15% of study participants in the dry, 25% in the rainy and 32% in the cold season. Retinol concentrations varied according to age, sex, milk consumption level and pooled cattle milk retinol concentration. Effect sizes varied and not all were statistically significantly different. Pooled cattle milk retinol concentrations varied seasonally and were positively associated to human retinol concentrations. This study establishes seasonal variation in human blood and pooled cattle milk retinol concentrations in Chad, demonstrating a linkage from animals to humans through milk. Rapid analysis using portable technology is feasible in remote populations under harsh climatic conditions., (Copyright © 2016. Published by Elsevier B.V.)

A comparative study between passive and active surveillance based on herd visits (villages) was conducted over a period of 24 months. It included 106 surveillance stations of the animal disease epidemiological surveillance network in Chad distributed randomly into 52 stations of active surveillance and 54 stations of passive surveillance. Nine diseases of various vaccination and expected prevalence status were monitored. The active surveillance stations carried out four herd visits monthly to look for the diseases under surveillance and organised four farmers awareness-raising meetings to stimulate them to make disease notifications. The passive surveillance stations held each month four farmer awareness-raising meetings. The suspicions recorded by the stations were consigned to a suspicion form specific to each disease, indicating whether a call from the farmer, a visit to the herd or a awareness-raising meeting was the source. The results showed that, irrespective of surveillance type, all diseases under surveillance, except the rare diseases (Rinderpest and Rift Valley Fever) were reported by the surveillance agents. However, suspicions recorded following farmer calls are significantly more important than suspicions carried out during herd visits or meetings. Nevertheless, a considerable number of suspicions is recorded during awareness-raising meetings. Finally approximately 83% of the herd visits realised by the active surveillance stations showed negative results (no suspicion identified). Passive surveillance stimulated by awareness-raising meetings appears to be better adapted to Chads conditions and less expensive for the surveillance of existing diseases. However, for the rare diseases, other methods of specific active surveillance (such as for example sentinel herds) remain important to complete passive surveillance., (Copyright © 2010 Elsevier B.V. All rights reserved.)

As a part of an interdisciplinary research and action programme, morbidity and nutritional patterns were assessed in three nomadic communities: Fulani and Arab cattle breeders and Arab camel breeders, of two prefectures in Chad. The predominant morbidity pattern of Chadian nomadic pastoralists (representing approximately 10% of the total population of the country) had not been documented so far. A total of 1092 women, men and children was examined by a physician and interviewed during two surveys in the dry season and one in the wet season (1999--2000). Participants with no complaint were rare. Pulmonary disorders (e.g. bronchitis) were most often diagnosed for children under 5 years of age. Of the adult participants, 4.6% were suspected of tuberculosis. Febrile diarrhoea occurred more often during the wet season when access to clean drinking water was precarious. Malaria was only rarely clinically diagnosed among Arabs during the dry season, whereas Fulani, who stayed in the vicinity of Lake Chad, were also affected during this period. A 24-h dietary recall showed that less Arab women than men consumed milk during the dry season (66% versus 92%). Malnutrition was only documented for 3 out of 328 children (0--14 years). Arab women in childbearing age had a higher proportion of children not surviving when compared to Fulani women (0.2 versus 0.07). This study identified several implications for reseach and interventions in nomadic settings. Innovative and integrated health services for nomads can possibly be extended to many settings as nomadic pastoralists have in common a similar way of life driven by the needs of their animals.

A large outbreak of meningococcal meningitis (Serogroup A) occurred in southern Chad in 1990. We describe the epidemic in the town of Sarh, where a mass vaccination against meningococcal meningitis had taken place two years before, in 1988 (estimated coverage: 66%). Early warning that an epidemic was imminent was given at the end of February, following more than 15 recorded cases per 100,000 population on 3 consecutive weeks. This threshold proved to be adequate to predict the outbreak. A total of 721 cases were recorded at Sarh hospital and at a nearby health centre. Direct agglutination tests confirmed that Neisseria meningitis serogroup A was the only causative agent. The overall incidence rate in this population of 80,000 was 0.9%. The highest weekly incidence rate was 186 cases per 100,000 population. The mean age of the patients was 12.6 years and age-specific incidence rates ranged from 0.23% to 1.42%. The male/female sex ratio was 1.36. Overall, the mortality among hospitalized patients was 7.9%. Mortality increased during the epidemic. The major risk factor for dying was the delay until reaching hospital. Only 4 out of 29 interviewed parents said that their child had been vaccinated two years before. Among adult patients this proportion was 12/38 (32%). Because of the small numbers and because of the impossibility to check the vaccination records it was not possible to assess precisely the impact of earlier mass vaccination. However, the previous mass vaccination did not prevent this major epidemic and its impact is likely to have been unimportant.