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Background: Peridomestic animals play a role in maintaining residual transmission of Plasmodium, being alternative blood meal sources for malaria vectors. The blood of animals treated with veterinary formulations of ivermectin show a mosquitocidal effect on malaria vectors, but for a too short period of time to impact Plasmodium transmission. This study proposes to treat cattle with innovative long-acting (six months) injectable formulations of ivermectin as a complementary vector control measure.Methods: The local breeds of cattle were used in two treatment arms (Four cattle injected with two long-acting formulations of ivermectin with the BEPO® technology at the therapeutic dose of 1.2 mg/kg, and two control arms (Four cattle injected with the vehicles of the formulations). The lethality of the formulations was evaluated on 3-5 days old Anopheles coluzzii mosquitoes through direct-skin feeding assays, from one to 210 days after treatments. Formulations’ efficacy was evaluated and compared using Cox proportional hazards survival models, Kaplan-Meier estimates and 4 parameters log-logistic regression on cumulative mortalities. These results were extrapolated to field scenarii using entomological and transmission models, considering different mosquito feeding preferences, hosts abundances, and bed nets uses ratios. Results: Both formulations released mosquitocidal concentrations of ivermectin until 210 days post-treatment (Hazard ratios > 1). The treatments significantly reduced mosquito survival, with the average median survival times of 4-5 days post-feeding. The Lethal Concentrations to kill 50% of the Anopheles (LC50) before they become infectious (10 days after infectious blood meal) were reached until 210 days post injection for both formulations. Modeling showed that administering long-acting ivermectin formulations to calves would significantly decrease Anopheles populations in the fields. The population of infectious vectors may decrease from 35% to 75% depending mostly on the mosquito feeding preference and on the hosts species relative availability.Conclusions: This study shows that, in complement to bed nets, a long-lasting BEPO® formulation of ivermectin injected to cattle could help to decrease field populations of malaria mosquitoes and residual transmission, the impact of this approach being dependant on the field epidemiological context.

SummaryContextIn the current context of residual plasmodium transmission where zoophagic proclivities of Anopheles intervene, we propose to treat peridomestic animals using the endectocide Ivermectin as a complementary approach to bednets. As Ivermectin remanence with classic veterinary compounds is insufficient to induce a significant decrease in vectors’ populations, we developed a long-lasting injectable formulation of ivermectin from the BEPO® technology designed to release insecticidal concentrations of the molecule for 6 months. The work reported here is a proof of concept that using this new technology could help decrease field Anopheles populations.MethodsEight calves were injected with Ivermectin therapeutic doses of 1.2 mg/kg body weight using 2 long lasting formulations (A and B). Efficacy of the product at killing wild derived An. coluzzii has been evaluated by direct-skin feeding assays from 1 to 210 days after injection (DAI). Efficacy on survival was estimated with Cox proportional hazards mixed models and Kaplan meier estimates. To predict efficacy in field-based scenarii, we used a transmission model fed with an entomological model considering different levels for the Anopheles’ zoophagic preference, calves vs humans ratios, and bed net use variables.ResultsThe release at mosquitocidal plasmatic concentrations of Ivermectin during 6 months is confirmed for both formulations (Hazard ratios > 1 for both formulations against their vehicle for 210 days). The Ivermectin concentration allowing to kill 90% of the mosquitoes before the extrinsic incubation period of the parasite is achieved (10 days) are 11 and 9 ng/ml for formulations A and B if the blood meal is taken before the infectious one, and 15 and 13 ng/ml if it was taken after. Modeling showed that Ivermectin treatment of calves using BEPO® technology would reduce infectious vector populations, from at least 35% for most anthropophagic Anopheles in villages where cattle to human ratio is the lowest, to more than 75% if vectors were zoophagic and calves numbers superior to humans’.ConclusionOur study gives the proof of concept that a long-lasting formulation of Ivermectin administered to calves could help decrease field malaria vectors’ populations, which may, ultimately, have an impact at the epidemiological level.

Background African animal trypanosomosis (AAT), transmitted by tsetse flies, is arguably the main disease constraint to integrated crop-livestock agriculture in sub-Saharan Africa, and African heads of state and governments adopted a resolution to rid the continent of this scourge. In order to sustainably reduce or eliminate the burden of AAT, a progressive and evidence-based approach is needed, which must hinge on harmonized, spatially explicit information on the occurrence of AAT and its vectors. Methods A digital repository was assembled, containing tsetse and AAT data collected in Burkina Faso between 1990 and 2019. Data were collected either in the framework of control activities or for research purposes. Data were systematically verified, harmonized, georeferenced and integrated into a database (PostgreSQL). Entomological data on tsetse were mapped at the level of individual monitoring traps. When this was not possible, mapping was done at the level of site or location. Epidemiological data on AAT were mapped at the level of location or village. Results Entomological data showed the presence of four tsetse species in Burkina Faso. Glossina tachinoides, present from the eastern to the western part of the country, was the most widespread and abundant species (56.35% of the catches). Glossina palpalis gambiensis was the second most abundant species (35.56%), and it was mainly found in the west. Glossina morsitans submorsitans was found at lower densities (6.51%), with a patchy distribution in the southern parts of the country. A single cluster of G. medicorum was detected (less than 0.25%), located in the south-west. Unidentified tsetse flies accounted for 1.33%. For the AAT component, data for 54,948 animal blood samples were assembled from 218 geographic locations. The samples were tested with a variety of diagnostic methods. AAT was found in all surveyed departments, including the tsetse-free areas in the north. Trypanosoma vivax and T. congolense infections were the dominant ones, with a prevalence of 5.19 ± 18.97% and 6.11 ± 21.56%, respectively. Trypanosoma brucei infections were detected at a much lower rate (0.00 ± 0.10%). Conclusions The atlas provides a synoptic view of the available information on tsetse and AAT distribution in Burkina Faso. Data are very scanty for most of the tsetse-free areas in the northern part of the country. Despite this limitation, this study generated a robust tool for targeting future surveillance and control activities. The development of the atlas also strengthened the collaboration between the different institutions involved in tsetse and AAT research and control in Burkina Faso, which will be crucial for future updates and the sustainability of the initiative. Graphical Abstract

L’objectif de cette étude était d’évaluer les Connaissances, Attitudes et Pratiques (CAP) chez les sportifs face aux conduites dopantes dans la ville de Bobo-Dioulasso au Burkina Faso. Il s’est agi d’une étude transversale, de novembre 2020 à janvier 2021, portant sur 390 sportifs de trois disciplines sportives: football, basketball, et handball. Les données ont été collectées à partir de questionnaires anonymes administrés ou auto-administrés. Au total, 73.1% (285) des sportifs ont participé à l’étude. Le sexe masculin était majoritaire, soit un sex-ratio de 2.47 et l’âge moyen des sportifs était de 21.4±3.68 ans. De plus, 69.12% (197) des sportifs ont déclaré avoir des connaissances sur le dopage ou sur les conduites dopantes et que les canaux privilégiés étaient les mass médias (55.79%) et les amis (10.18%). A l’issue de l’enquête CAP, 76.84% (219) ont déclaré pratiqué les conduites dopantes (p

Background Copy number variation is an important class of genomic variation that has been reported in 75% of the human genome. However, it is underreported in African populations. Copy number variants (CNVs) could have important impacts on disease susceptibility and environmental adaptation. To describe CNVs and their possible impacts in Africans, we sequenced genomes of 232 individuals from three major African ethno-linguistic groups: (1) Niger Congo A from Guinea and Côte d’Ivoire, (2) Niger Congo B from Uganda and the Democratic Republic of Congo and (3) Nilo-Saharans from Uganda. We used GenomeSTRiP and cn.MOPS to identify copy number variant regions (CNVRs). Results We detected 7608 CNVRs, of which 2172 were only deletions, 2384 were only insertions and 3052 had both. We detected 224 previously un-described CNVRs. The majority of novel CNVRs were present at low frequency and were not shared between populations. We tested for evidence of selection associated with CNVs and also for population structure. Signatures of selection identified previously, using SNPs from the same populations, were overrepresented in CNVRs. When CNVs were tagged with SNP haplotypes to identify SNPs that could predict the presence of CNVs, we identified haplotypes tagging 3096 CNVRs, 372 CNVRs had SNPs with evidence of selection (iHS > 3) and 222 CNVRs had both. This was more than expected (p Conclusions Novel CNVRs in the current study increase representation of African diversity in the database of genomic variants. Over-representation of CNVRs in SNP signatures of selection and an excess of SNPs that both tag CNVs and are subject to selection show that CNVs may be the actual targets of selection at some loci. However, unlike SNPs, CNVs alone do not resolve African ethno-linguistic groups. Tag haplotypes for CNVs identified may be useful in predicting African CNVs in future studies where only SNP data is available.

Background Tsetse flies are vectors of African trypanosomes, protozoan parasites that cause sleeping sickness (or human African trypanosomosis) in humans and nagana (or animal African trypanosomosis) in livestock. In addition to trypanosomes, four symbiotic bacteria Wigglesworthia glossinidia, Sodalis glossinidius, Wolbachia, Spiroplasma and one pathogen, the salivary gland hypertrophy virus (SGHV), have been reported in different tsetse species. We evaluated the prevalence and coinfection dynamics between Wolbachia, trypanosomes, and SGHV in four tsetse species (Glossina palpalis gambiensis, G. tachinoides, G. morsitans submorsitans, and G. medicorum) that were collected between 2008 and 2015 from 46 geographical locations in West Africa, i.e. Burkina Faso, Mali, Ghana, Guinea, and Senegal. Results The results indicated an overall low prevalence of SGHV and Wolbachia and a high prevalence of trypanosomes in the sampled wild tsetse populations. The prevalence of all three infections varied among tsetse species and sample origin. The highest trypanosome prevalence was found in Glossina tachinoides (61.1%) from Ghana and in Glossina palpalis gambiensis (43.7%) from Senegal. The trypanosome prevalence in the four species from Burkina Faso was lower, i.e. 39.6% in Glossina medicorum, 18.08%; in Glossina morsitans submorsitans, 16.8%; in Glossina tachinoides and 10.5% in Glossina palpalis gambiensis. The trypanosome prevalence in Glossina palpalis gambiensis was lowest in Mali (6.9%) and Guinea (2.2%). The prevalence of SGHV and Wolbachia was very low irrespective of location or tsetse species with an average of 1.7% for SGHV and 1.0% for Wolbachia. In some cases, mixed infections with different trypanosome species were detected. The highest prevalence of coinfection was Trypanosoma vivax and other Trypanosoma species (9.5%) followed by coinfection of T. congolense with other trypanosomes (7.5%). The prevalence of coinfection of T. vivax and T. congolense was (1.0%) and no mixed infection of trypanosomes, SGHV and Wolbachia was detected. Conclusion The results indicated a high rate of trypanosome infection in tsetse wild populations in West African countries but lower infection rate of both Wolbachia and SGHV. Double or triple mixed trypanosome infections were found. In addition, mixed trypanosome and SGHV infections existed however no mixed infections of trypanosome and/or SGHV with Wolbachia were found. Electronic supplementary material The online version of this article (10.1186/s12866-018-1287-4) contains supplementary material, which is available to authorized users.

Background Diminazene diaceturate (DA) and isometamidium chloride hydrochloride (ISM) are with homidium bromide, the main molecules used to treat African Animal Trypanosomosis (AAT). These drugs can be purchased from official suppliers but also from unofficial sources like local food markets or street vendors. The sub-standard quality of some of these trypanocides is jeopardizing the efficacy of treatment of sick livestock, leading thus to economic losses for the low-resource farmers and is contributing to the emergence and spread of drug resistance. The objective of this study was to assess the quality of trypanocidal drugs sold in French speaking countries of West Africa. In total, 308 drug samples including 282 of DA and 26 of ISM were purchased from official and unofficial sources in Benin, Burkina Faso, Côte d’Ivoire, Mali, Niger and Togo. All samples were analysed at LACOMEV (Dakar, Senegal), a reference laboratory of the World Organisation for Animal Health, by galenic inspection and high performance liquid chromatography. Results The results showed that 51.90% of the samples were non-compliant compared to the standards and were containing lower quantity of the active ingredient compared to the indications on the packaging. The non-compliances ranged from 63.27% in Togo to 32.65% in Burkina Faso (61.82% in Benin, 53.84% in Mali, 50% in Côte d’Ivoire, 47.36% in Niger). The rates of non-compliance were not statistically different (P = 0.572) from official or unofficial suppliers and ranged from 30 to 75% and from 0 to 65% respectively. However, the non-compliance was significantly higher for ISM compared to DA (P = 0.028). Conclusions The high non-compliance revealed in this study compromises the efficacy of therapeutic strategies against AAT, and is likely to exacerbate chemoresistance in West Africa. Corrective actions against sub-standard trypanocides urgently need to be taken by policy makers and control authorities.

Tsetse flies are cyclical vectors of trypanosomes, the causative agents of sleeping sickness or Human African Trypanosomosis and nagana or African Animal Trypanosomosis in Sub-Saharan Africa. The Insectarium de Bobo-Dioulasso (IBD) was created and equipped in the frame of Pan African Tsetse and Trypanosomosis Eradication Campaign (PATTEC) with the main goal to provide sterile males for the different eradication programs in West Africa which is already the case with the ongoing eradication program in Senegal. The aim of this study was to identify the best feeding regime in mass-rearing colonies of Glossina palpalis gambiensis to optimize the yield of sterile males. We investigated the mortality and fecundity for various feeding regimes and day alternation (3×: Monday-Wednesday-Friday, 4×: Monday-Wednesday-Friday-Saturday, 4×: Monday-Wednesday-Thursday-Friday and 6×: all days except Sunday) on adult tsetse flies in routine rearing over 60 days after emergence. The day alternation in the 4 blood meals per week (feeding regimes 2 and 3) had no effect on tsetse fly mortality and fecundity. The best feeding regime was the regime of 4 blood meals per week which resulted in higher significant fecundity (PPIF = 2.5; P = 0.003) combined with lower mortality of females (P = 0.0003) than the 3 blood meals per week (PPIF = 2.0) and in similar fecundity (PPIF = 2.6; P = 0.70) and mortality (P = 0.51) than the 6 blood meals per week. This feeding regime was extended to the whole colonies, resulting in an improved yield of sterile males for the ongoing eradication program in Senegal and would be more cost-effective for the implementation of the next-coming sterile insect technique (SIT) programs in West Africa.

Le système d’information géographique constitue une aide considérable lors de la définition d’un plan de lutte contre les glossines. Son application pratique pour la collecte de données entomologiques servant de base à la planification de la lutte et à son évaluation future a été faite dans l’ouest du Burkina Faso, de décembre 2007 à novembre 2008. Choisie pour englober les bassins versants des principaux fleuves ou rivières et les limites de distribution de Glossina palpalis gambiensis et G. tachinoides, la zone d’étude a été divisée en cellules de 10 km x 10 km. Dans chaque cellule, un maximum de 13 sites potentiels de piégeage ont été sélectionnés par l’utilisation d’imagerie satellite, puis repérés sur le terrain à l’aide du système mondial de positionnement (GPS). L’enquête entomologique a été réalisée avec des pièges biconiques Challier-Laveissière et les récoltes ont eu lieu 72 heures après leur installation. L’analyse des données a été conduite en utilisant des modèles aléa­toires mixtes binomiaux et de distribution de Poisson. La cartographie, réalisée avec le logiciel Arc Gis 9.3, a permis de déterminer la limite nord (12° 45’ N) des glos­sines dans la zone d’intervention. Les proportions de sites infestés étaient de 89,6 et 76,4 % respectivement au niveau des sections ascendante et descendante de la rivière Mouhoun (la première coule vers le nord-est depuis la source, la seconde vers le sud-est puis le sud après avoir conflué avec le Sourou), et de 16,7 et 10,3 % respectivement au niveau de leurs affluents. Entre les isohyètes 700–800 m et 800–900 m aucune différence significative n’a été observée dans les densités apparentes des glossines par piège, ni dans les sites infestés. Les deux espèces de glossines cap­turées étaient distribuées différemment selon les sections du Mouhoun : les cap­tures étaient composées de 79,5 % de G. p. gambiensis sur la section ascendante et de 96,0 % de G. tachinoides sur la section descendante. Les captures de vecteurs mécaniques ont été relativement faibles, leur distribution étant comparable à celle des glossines avec cependant quelques densités importantes sur les affluents.

Background Tsetse flies are the sole vectors of human and animal trypanosomosis. In Burkina Faso, a project aiming to create zones free of tsetse flies and trypanosomosis was executed from June 2006 to December 2013. After the determination of tsetse distribution in the intervention area from December 2007 to November 2008, the control campaign was launched in November 2009 and ended in December 2013. The goal was to eliminate tsetse flies from 40,000 km2 of area, through an integrated control campaign including insecticide targets, traps and cattle, sequential aerial treatment (SAT) and the mass treatment of livestock using trypanocides. The campaign involved assistance of the beneficiary communities at all the steps of the control strategy with insecticide impregnated targets. Methods This study was carried out to assess the impact of the control project on tsetse apparent density per trap per day (ADT). To evaluate the effectiveness of tsetse control, 201 sites were selected based on the baseline survey results carried out from December 2007 to November 2008. These sites were monitored bi-monthly from January 2010 to November 2012. At the end-of-study in 2013 a generalized entomological survey was carried out in 401 infested sites found during the longitudinal survey done before the control. Barrier and tsetse persistence areas were treated by ground spraying and evaluated. Controls were also done before and after aerial spraying. Results In the insecticide-impregnated target area, the control showed that ADT of tsetse flies declined from 10.73 (SD 13.27) to 0.43 (SD 2.51) fly/trap/day from the third month of campaign onwards (P

BackgroundThere are over 2000 genetically diverse ethno-linguistic groups in Africa that could help decipher human evolutionary history and the genetic basis of phenotypic variation. We have sequenced 300 genomes from Niger-Congo populations from six sub-Saharan African countries (Uganda, Democratic Republic of Congo, Cameroon, Zambia, Ivory Coast, Guinea) and a Nilo-Saharan population from Uganda. Of these, we analysed 289 samples for population structure, genetic admixture, population history and signatures of selection. These samples were collected as part of the TrypanoGEN consortium project [1].ResultsThe population genetic structure of the 289 individuals revealed four clusters, which correlated with ethno-linguistic group and geographical latitude. These were the West African Niger-Congo A, Central African Niger-Congo B, East African Niger-Congo B and the Nilo-Saharan. We observed a spatial distribution of positive natural selection signatures in genes previously associated with AIDS, Tuberculosis, Malaria and Human African Trypanosomiasis among the TrypanoGEN samples. Having observed a marked difference between the Nilo-Saharan Lugbara and Niger-Congo populations, we identified four genes (APOBEC3G, TOP2B, CAPN9, LANCL2), which are highly differentiated between the two ethnic groups and under positive selection in the Lugbara population (_iHS -log p > 3.0, Rsb -log p > 3.0, Fst > 0.1 bonferroni p > 1.8x10e4).ConclusionThe signatures that differentiate ethnically distinct populations could provide information on the specific ecological adaptations with respect to disease history and susceptibility/resistance. For instance in this study we identified APOBEC3G which is believed to be involved in the susceptibility of the Nilo-Saharan Lugbara population to Hepatitis B virus infection.

In the context of the Pan African Tsetse and Trypanosomiasis Eradication Campaign, the value of tsetse saliva antibodies as a biomarker of cattle exposure to tsetse flies was evaluated, as this could provide an alternative and complementary tool to conventional entomological methods. Serum immune reactivity to Glossina (G.) palpalis (p.)gambiensis, G. tachinoides and G. morsitans (m.) submorsitans whole saliva extracts (WSE) were monitored in cattle from both tsetse free and tsetse infested areas, and in cows experimentally exposed to tsetse flies and other hematophagous arthropods. In the tsetse infested area, cattle IgG responses to Glossina WSE were significantly higher during the dry season (p < 0.0001) when herds are most exposed to tsetse flies and in infected animals (p = 0.01) as expected in the case of a biomarker of exposure. Experimental studies further confirmed this as a quick rise of specific IgGs was observed in animals exposed to tsetse flies (within weeks), followed by a rapid clearance after exposure was stopped. In contrast to the two other tsetse species, G. m. submorsitans WSE enabled to detect exposure to all tsetse species and were associated with low level of cross-reactivity to other blood sucking arthropods. Finally, IgG responses to G. m. submorsitans salivary antigens enabled to distinguish different groups of cows according to exposure levels, thus indicating that tsetse saliva antibodies are not only indicators of tsetse exposure but also are correlated to the intensity of tsetse contacts (p = 0.0031). Implementation of this new sero-epidemiological marker of cattle exposure to tsetse flies in the framework of tsetse elimination campaigns is discussed.

In view of gathering baseline information about the prevalence of animal trypanosomosis, the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) funded a cross sectional survey in the region of the Boucle du Mouhoun which constitutes the Northern limit of the tsetse distribution in Burkina. This cross sectional study was carried out in 53 villages located in the six provinces of the region. A total of 2002 cattle, 1466 small ruminants and 481 donkeys were sampled. This survey showed that about 25% of the cattle had been treated with trypanocidal drugs within 3 months before the survey compared to 3% and 0.42% for the small ruminants and donkeys, respectively. Parasitological prevalence in cattle was low: 0.77% (95% C.I. 0.30-1.95%). No goats and three donkeys were found infected with trypanosomes. Infections were mainly due to Trypanosoma vivax (75.0%) with cases of Trypanosoma congolense (25.0%). In cattle, the serological prevalence of trypanosomosis, for the entire region of the Boucle du Mouhoun, was 34.2% (95% C.I. 26.1-43.4%). For sheep, goats and donkeys, the prevalence were of 20.9% (95% C.I. 12.2-33.5%), 8.5% (95% C.I. 5.7-12.5%) and 5.8% (95% C.I. 3.9-8.6%), respectively. The age and distance to the river were the two main risk factors associated with seropositivity.

OBJECTIVES Adverse events during antiretroviral treatment are frequent and various. Their diagnosis incurs some various difficulties according to the geographic context. Our aim was to describe the frequency, nature, and preventability of adverse drug reactions (ADRs) due to antiretroviral treatment in Malian outpatient children. METHODS The study was a 6-month (June 1 to November 30, 2010) prospective, observational study of 92 children admitted to a pediatric hospital in Sikasso, Mali. The patients were treated with a generic drug and/or drug combinations. Prior to treatment initiation, demographic characteristics, clinical history, and biologic parameters, including CD4 cell counts, were collected for each patient. The World Health Organization's adverse drug reactions classification was used to characterize the side effects. Adverse effects and toxicities were graded 1, 2, and 3. Analysis of data was performed using SPSS Version 17.0 software. RESULTS Ninety-two human immunodeficiency virus–infected children met the criteria of inclusion. After 24 weeks of treatment, we observed that 14.1% of children had at least one side effect during our study. Side effects were many and varied, with the most frequent being cutaneous rash, nausea, vomiting, and diarrhea (38.5%, 23.1%, 15.4%, and 15.4%, respectively). Side effects were grade 1 in most cases. One case of grade 2 and one case of grade 3 were observed with rash. We observed one case of grade 3 side effects during our study. The treatment regimen was changed in 15.2% of cases, including one case because of side effects. CONCLUSION ADRs are not rare in Mali, particularly in children. These ADRs have an impact on quality of life for patients. We recommend a pharmacovigilance system for sustainable management of side effects in patients infected with human immunodeficiency virus in Mali.

La pression trypanosomienne demeure un obstacle pour le developpement durable de l’elevage en Afrique subsaharienne, en particulier dans le bassin du Mouhoun, au Burkina Faso. Aujourd’hui, l’utilisation des savoirs locaux et l’implication des communautes rurales apparaissent indispensables dans les projets de lutte contre les trypanosomoses animales africaines (TAA). Deux methodes participatives ont ete utilisees : la rapid rural appraisal (RRA) et la methode acceleree de recherche participative (MARP). Elles ont permis de decrire deux types de systemes d’exploitation en se basant sur le mode d’elevage. La perception du risque dans les differents groupes a ete evaluee par des methodes qualitatives et par scoring sur la base de questionnaires semi-ouverts : elle etait principalement liee au site et concordait plus ou moins avec le risque estime par la serologie et l’entomologie, avec cependant moins d’exactitude et de precision. Les strategies de controle des TAA, basees essentiellement sur l’usage des trypanocides, etaient encore largement decidees et mises en œuvre par les eleveurs eux-memes. La MARP a revele que l’evitement des contacts hotes/vecteurs etait une strategie efficace mais rarement realisable. Ces methodes d’epidemiologie participative constituent des outils pratiques de conseil sanitaire adaptes au contexte.

Background The Government of Senegal has embarked several years ago on a project that aims to eradicate Glossina palpalis gambiensis from the Niayes area. The removal of the animal trypanosomosis would allow the development more efficient livestock production systems. The project was implemented using an area-wide integrated pest management strategy including a sterile insect technique (SIT) component. The released sterile male flies originated from a colony from Burkina Faso. Methodology/Principal Findings Monitoring the efficacy of the sterile male releases requires the discrimination between wild and sterile male G. p. gambiensis that are sampled in monitoring traps. Before being released, sterile male flies were marked with a fluorescent dye powder. The marking was however not infallible with some sterile flies only slightly marked or some wild flies contaminated with a few dye particles in the monitoring traps. Trapped flies can also be damaged due to predation by ants, making it difficult to discriminate between wild and sterile males using a fluorescence camera and / or a fluorescence microscope. We developed a molecular technique based on the determination of cytochrome oxidase haplotypes of G. p. gambiensis to discriminate between wild and sterile males. DNA was isolated from the head of flies and a portion of the 5’ end of the mitochondrial gene cytochrome oxidase I was amplified to be finally sequenced. Our results indicated that all the sterile males from the Burkina Faso colony displayed the same haplotype and systematically differed from wild male flies trapped in Senegal and Burkina Faso. This allowed 100% discrimination between sterile and wild male G. p. gambiensis. Conclusions/Significance This tool might be useful for other tsetse control campaigns with a SIT component in the framework of the Pan-African Tsetse and Trypanosomosis Eradication Campaign (PATTEC) and, more generally, for other vector or insect pest control programs., Author Summary The Government of Senegal has embarked since several years on a project that aims to create a tsetse-free area in the Niayes. The project was implemented using an area-wide integrated pest management (AW-IPM) strategy where the sterile flies used for the sterile insect technique (SIT) component were derived from a colony originating from Burkina Faso. Monitoring the efficacy of the sterile male releases requires the discrimination between wild and sterile males that are sampled in monitoring traps. Before being released, sterile males were marked with a fluorescent dye powder. The marking was however not infallible with some sterile flies only slightly marked or some wild flies contaminated with a few dye particles in the monitoring traps, making it difficult to discriminate between wild and sterile males using a UV camera. We developed a molecular technique based on the cytochrome oxidase gene that efficiently discriminates between wild and sterile males. This tool might be useful for other tsetse control campaigns with a SIT component or for other vector or insect pest control programs.

Background The saliva of tsetse flies contains a cocktail of bioactive molecules inducing specific antibody responses in hosts exposed to bites. We have previously shown that an indirect-ELISA test using whole salivary extracts from Glossina morsitans submorsitans was able to discriminate between (i) cattle from tsetse infested and tsetse free areas and (ii) animals experimentally exposed to low or high numbers of tsetse flies. In the present study, our aim was to identify specific salivary synthetic peptides that could be used to develop simple immunoassays to measure cattle exposure to tsetse flies. Methods In a first step, 2D-electrophoresis immunoblotting, using sera from animals exposed to a variety of bloodsucking arthropods, was performed to identify specific salivary proteins recognised in cattle exposed to tsetse bites. Linear epitope prediction software and Blast analysis were then used to design synthetic peptides within the identified salivary proteins. Finally, candidate peptides were tested by indirect-ELISA on serum samples from tsetse infested and tsetse free areas, and from exposure experiments. Results The combined immunoblotting and bioinformatics analyses led to the identification of five peptides carrying putative linear epitopes within two salivary proteins: the tsetse salivary gland protein 1 (Tsal1) and the Salivary Secreted Adenosine (SSA). Of these, two were synthesised and tested further based on the absence of sequence homology with other arthropods or pathogen species. IgG responses to the Tsal152–75 synthetic peptide were shown to be specific of tsetse exposure in both naturally and experimentally exposed hosts. Nevertheless, anti-Tsal152–75 IgG responses were absent in animals exposed to high tsetse biting rates. Conclusions These results suggest that Tsal152–75 specific antibodies represent a biomarker of low cattle exposure to tsetse fly. These results are discussed in the light of the other available tsetse saliva based-immunoassays and in the perspective of developing a simple serological tool for tsetse eradication campaigns to assess the tsetse free status or to detect tsetse reemergence in previously cleared areas. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1414-8) contains supplementary material, which is available to authorized users.

Background: Tsetse flies occur in much of sub-Saharan Africa where they are vectors of trypanosomes that cause human and animal African trypanosomosis. The sterile insect technique (SIT) is currently used to eliminate tsetse fly populations in an area-wide integrated pest management (AW-IPM) context in Senegal and Ethiopia. Three Glossina palpalis gambiensis strains [originating from Burkina Faso (BKF), Senegal (SEN) and an introgressed strain (SENbkf)] were established and are now available for use in future AW-IPM programmes against trypanosomes in West Africa. For each strain, knowledge of the environmental survival thresholds is essential to determine which of these strains is best suited to a particular environment or ecosystem, and can therefore be used effectively in SIT programmes. Methods: In this paper, we investigated the survival and fecundity of three G. p. gambiensis strains maintained under various conditions: 25 degrees C and 40, 50, 60, and 75 % relative humidity (rH), 30 degrees C and 60 % rH and 35 degrees C and 60 % rH. Results: The survival of the three strains was dependent on temperature only, and it was unaffected by changing humidity within the tested range. The BKF strain survived temperatures above its optimum better than the SEN strain. The SENbkf showed intermediate resistance to high temperatures. A temperature of about 32 degrees C was the limit for survival for all strains. A rH ranging from 40 to 76 % had no effect on fecundity at 25-26 degrees C. Conclusions: We discuss the implications of these results on tsetse SIT-based control programmes.

Background The success of current control tools in combatting malaria vectors is well established. However, sustained residual transmission of Plasmodium parasites persists. Mass drug administration (MDA) to humans of the endectocide ivermectin for vector control is receiving increasing attention. However, vectors feeding upon animals escape this promising approach. Zoophagy of mosquitoes sustains both the vector population and endemic population of vector-borne pathogens. Therefore, only a strategy that will combine ivermectin MDAs targeted at humans and their peridomestic animals could be successful at controlling residual malaria transmission. Methods Burkinabé cattle have been treated with injectable therapeutic dose of ivermectin (0.2 mg/kg of body weight) to render blood meals toxic to field representative populations of Anopheles coluzzii carrying the kdr mutation. Direct skin-feeding assays were performed from 2 to 28 days after injection (DAI) and mosquitoes were followed for their survival, ability to become gravid and fecundity. Membrane feeding assays were further performed to test if an ivermectin blood meal taken at 28 DAI impacts gametocyte establishment and development in females fed with infectious blood. Results The mosquitocidal effect of ivermectin is complete for 2 weeks after injection, whether 12 days cumulative mortalities were of 75 and 45 % the third and fourth weeks, respectively. The third week, a second ivermectin blood meal at sub-lethal concentrations further increased mortality to 100 %. Sub-lethal concentrations of ivermectin also significantly decreased egg production by surviving females, increasing further the detrimental effect of the drug on vector densities. Although females fitness was impaired by sub-lethal ivermectin blood meals, these did not diminish nor increase their susceptibility to infection. Conclusion This study demonstrates the potential of integrated MDA of ivermectin to both human and peridomestic cattle to target vector reservoirs of residual malaria transmission. Such integration lies in ‘One-Health’ efforts being implemented around the globe, and would be especially relevant in rural communities in Africa where humans are also at risk of common zoonotic diseases. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-1001-z) contains supplementary material, which is available to authorized users.

African animal trypanosomosis is a parasitic blood disease transmitted by tsetse flies and is widespread in sub-Saharan Africa. West African taurine breeds have the ability, known as trypanotolerance, to limit parasitaemia and anaemia and remain productive in enzootic areas. Several quantitative trait loci (QTL) underlying traits related to trypanotolerance have been identified in an experimentally infected F2 population resulting from a cross between taurine and zebu cattle. Although this information is highly valuable, the QTL remain to be confirmed in populations subjected to natural conditions of infection, and the corresponding regions need to be refined. In our study, 360 West African cattle were phenotyped for the packed cell volume control under natural conditions of infection in south-western Burkina Faso. Phenotypes were assessed by analysing data from previous cattle monitored over 2 years in an area enzootic for trypanosomosis. We further genotyped for 64 microsatellite markers mapping within four previously reported QTL on BTA02, BTA04, BTA07 and BTA13. These data enabled us to estimate the heritability of the phenotype using the kinship matrix between individuals computed from genotyping data. Thus, depending on the estimators considered and the method used, the heritability of anaemia control ranged from 0.09 to 0.22. Finally, an analysis of association identified an allele of the MNB42 marker on BTA04 as being strongly associated with anaemia control, and a candidate gene, INHBA, as being close to that marker. (Resume d'auteur)

The present study was conducted to determine the prevalence and incidence of trypanosomosis and to investigate some factors influencing them in an agro-pastoral area of southwestern Burkina Faso. A total of 363 crossbred cattle (Baoule-zebu peul), which were bred under natural trypanosomosis challenge, were monitored monthly for parasitaemia, packed cell volume (PCV) and serological analyses over 2 years. The parasitological prevalence estimated at the beginning of the survey using the buffy coat technique (BCT) was 7.54%. As much as 66.7% of all trypanosome infections were due to Trypanosoma vivax, 23.8% due to Trypanosoma congolense and 9.5% due to T. vivax/T. congolense mixed infections. The monthly serological incidence varied from 0.29% to 19.29%. The season was the most important factor influencing the serological prevalence and incidence and the animal PCV. The dry hot season is associated with increasing seroprevalences and incidences and consequently a decreasing average of PCV. In addition, an important spatial heterogeneity was observed..

Summary Trypanocidal drugs are the most commonly purchased and used livestock input by resource-poor farmers in sub-Saharan Africa. The effective use of trypanocidal drugs by smallholder farmers is threatened by the development of widespread resistance. This is a particular concern for smallholder crop-livestock farmers in the cotton zone of West Africa. A recent project funded by the Germany Ministry for Economic Cooperation and Development (BMZ) confirmed significant resistance to trypanocidal drugs in villages with high trypanosomosis risk in Burkina Faso and Mali. Strategies for resistance prevention were investigated. Keeping trypanotolerant cattle was found to be an effective disease management strategy, but farmers’ preference for trypano-susceptible breeds, for reasons unrelated to animal health, suggest that the intromission of zebu genotype will continue. Community vector control was found to be effective in managing trypanosomosis in the presence of resistance and the high-level participatory approach tested was found to be more sustainable than low-level approaches previously used in the region. This suggests that participatory vector control with appropriate external support is likely to be a viable option for implementing resistance ‘clean-up’. Promoting rational drug use (RDU) emerged as a promising prevention strategy, with clear improvements in farmer knowledge, farmer practice and animal health outcomes. However, policy studies showed low understanding of the problem of resistance and the absence of an enabling environment for RDU. Engagement was initiated with actors involved in the problem of resistance and for its solution, including manufacturers, sellers and users of drugs, regulators and extension providers.

Background Human African trypanosomiasis (HAT) manifests as an acute form caused by Trypanosoma brucei rhodesiense (Tbr) and a chronic form caused by Trypanosoma brucei gambiense (Tbg). Previous studies have suggested a host genetic role in infection outcomes, particularly for APOL1. We have undertaken candidate gene association studies (CGAS) in a Ugandan Tbr and a Tbg HAT endemic area, to determine whether polymorphisms in IL10, IL8, IL4, HLAG, TNFA, TNX4LB, IL6, IFNG, MIF, APOL1, HLAA, IL1B, IL4R, IL12B, IL12R, HP, HPR, and CFH have a role in HAT. Methodology and results We included 238 and 202 participants from the Busoga Tbr and Northwest Uganda Tbg endemic areas respectively. Single Nucleotide Polymorphism (SNP) genotype data were analysed in the CGAS. The study was powered to find odds ratios > 2 but association testing of the SNPs with HAT yielded no positive associations i.e. none significant after correction for multiple testing. However there was strong evidence for no association with Tbr HAT and APOL1 G2 of the size previously reported in the Kabermaido district of Uganda. Conclusions/Significance A recent study in the Soroti and Kaberamaido focus in Central Uganda found that the APOL1 G2 allele was strongly associated with protection against Tbr HAT (odds ratio = 0.2, 95% CI: 0.07 to 0.48, p = 0.0001). However, in our study no effect of G2 on Tbr HAT was found, despite being well powered to find a similar sized effect (OR = 0.9281, 95% CI: 0.482 to 1.788, p = 0.8035). It is possible that the G2 allele is protective from Tbr in the Soroti/Kabermaido focus but not in the Iganga district of Busoga, which differ in ethnicity and infection history. Mechanisms underlying HAT infection outcome and virulence are complex and might differ between populations, and likely involve several host, parasite or even environmental factors., Author summary Human African Trypanosomiasis (HAT) occurs in two distinct disease forms; the acute form and the chronic form which are caused by microscopically indistinguishable hemo-parasites, Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense respectively. Uganda is the only country where both forms of the disease are found, though in geographically distinct areas. Recent studies have shown that host genetic factors play a role in HAT resistance and/or susceptibility, particularly by genes involved in the immune response. In this study, we identified single nucleotide polymorphisms in selected genes involved in immune responses and carried out a case-control candidate gene association study in Ugandan participants from the two endemic areas. We were unable to detect any polymorphisms that were robustly associated with either Tbr or Tbg HAT. However, our findings differ from recent studies carried out in the Tbr HAT another endemic area of Uganda that showed the APOL1 (Apolipoprotein 1) G2 allele to be protective against the disease which merits further investigation. Larger studies such as genome wide association studies (GWAS) by the TrypanoGEN network that has >3000 cases and controls covering seven countries (Cameroon, Cote d’Ivoire, DRC, Malawi, Uganda, Zambia) using the H3Africa customized chip reflective of African genetic diversity will present novel association targets (https://commonfund.nih.gov/globalhealth/h3aresources).

Tsetse-transmitted trypanosomiasis poses a serious threat to human and animal health in sub-Saharan Africa. The majority of tsetse flies (Glossina spp.) in a natural population will not develop a mature infection of either Trypanosoma congolense or Trypanosoma brucei sp. because of refractoriness, a phenomenon that is affected by different factors, including the tsetse fly's immune defence. Starvation of tsetse flies significantly increases their susceptibility to the establishment of a trypanosome infection. This paper reports the effects of nutritional stress (starvation) on (a) uninduced baseline levels of gene expression of the antimicrobial peptides attacin, defensin and cecropin in the tsetse fly, and (b) levels of expression induced in response to bacterial (Escherichia coli) or trypanosomal challenge. In newly emerged, unfed tsetse flies, starvation significantly lowers baseline levels of antimicrobial peptide gene expression, especially for attacin and cecropin. In response to trypanosome challenge, only non-starved older flies showed a significant increase in antimicrobial peptide gene expression within 5 days of ingestion of a trypanosome-containing bloodmeal, especially with T. brucei bloodstream forms. These data suggest that a decreased expression of immune genes in newly hatched flies or a lack of immune responsiveness to trypanosomes in older flies, both occurring as a result of fly starvation, may be among the factors contributing to the increased susceptibility of nutritionally stressed tsetse flies to trypanosome infection.

Les évolutions démographiques (population humaine multipliée par quatre en 50 ans), les changements climatiques et le développement économique survenus en Afrique de l’Ouest depuis maintenant un siècle ont profondément modifié le peuplement humain et les paysages dans lesquels il s’inscrit. Ces évolutions ne sont pas sans conséquences sur le complexe pathogène des trypanosomoses transmises par les glossines. En l’espace d’un siècle, la limite nord des tsé-tsé s’est déplacée vers le sud, accompagnant (mais à des échelles distinctes) la descente des isohyètes et des foyers de maladie du sommeil, autrefois présents en savane et qui sont actuellement répartis en zone forestière et en zone de mangrove. On met en évidence un impact clair de la pression anthropique sur le recul des glossines du groupe morsitans, vecteurs majeurs des trypanosomoses animales. En revanche, les glossines du groupe palpalis (notamment Glossina palpalis) s’adaptent aux fortes densités humaines et se maintiennent dans les plus grands centres urbains d’Afrique de l’Ouest, posant d’ailleurs la question du développement de foyers urbains dans les années à venir, comme en témoigne l’exemple récent de Kinshasa. L’étude des facteurs humains (dynamiques de peuplement) et environnementaux (changements climatiques et leurs impacts) dans l’espace et dans le temps, corrélée à celle des trypanosomoses et de leurs vecteurs devra permettre la mise en évidence des combinaisons spatiales capables d’expliquer la présence/absence de la maladie dans le but d’orienter les zones d’intervention médicale et anti-vectorielle. Ce type d’étude pourra être étendu à d’autres pathologies transmises par des vecteurs.

African animal trypanosomosis (AAT) is considered the most important cattle disease in sub-Saharan Africa but its diagnosis in the field is difficult, resulting in inappropriate treatments, excessive delay in treatments and under-treatment. A field study in West Africa investigated the usefulness of anemia in the diagnosis of trypanosomosis. A total of 20,772 cattle blood samples were taken from 121 villages in 3 countries. The average packed cell volume (PCV) of trypanosomosis positive cattle was 23%, versus 28% for negative cattle. In a sub-set of animals, other causes of anemia were investigated showing most of the anemia burden was attributable to trypanosomosis. Anemia was a reasonably accurate indicator of trypanosomosis in the study area, with a sensitivity of 56% and a specificity of 80% and a diagnostic odds ratio of 4.2, the highest of all the signs evaluated (anemia, emaciation, staring coat, lymphadenopathy, fever, lacrimation and salivary or nasal discharge). Having confirmed the usefulness of anemia as a predictor of trypanosomosis, two potential pen-side tests for anemia were evaluated (the first reported trial of their use in cattle), firstly a color chart developed for anemia detection in sheep through visual inspection of conjunctival membranes (FAMACHA) and secondly the Hemoglobin Color Scale (HbCS) developed for assessing hemoglobin levels in human patients by comparing blood drops on filter paper with color standards. In a population of cattle suspected by their owners to be sick with trypanosomosis (n=898) the sensitivity of the HbCS test was 56% and the specificity was 77%, while the sensitivity of the FAMACHA test was 95% and the specificity was 22%. The higher sensitivity but lower specificity suggests the FAMACHA may be useful as a screening test and the HbCS as a confirmatory test. The two tests were also evaluated in cattle randomly selected from the village herd. Using cut-off points to optimize test performance, the HbCS test had a sensitivity of 81% and a specificity of 62% (n=505 cattle), while the FAMACHA had a sensitivity of 92% and a specificity of 30% (n=298 cattle). Recommendations are made for the appropriate use of these tests in the West African region.

Background The application of the sterile insect technique (SIT) requires mass-production of sterile males of good biological quality. The size of the project area will in most cases determine whether it is more cost effective to produce the sterile flies locally (and invest in a mass-rearing facility) or import the sterile flies from a mass-rearing facility that is located in another country. This study aimed at assessing the effect of long distance transport of sterile male Glossina palpalis gambiensis pupae on adult male fly yield. Methods The male pupae were produced at the Centre International de Recherche-Développement sur l’Elevage en zone Subhumide (CIRDES), Bobo-Dioulasso, Burkina Faso, and shipped with a commercial courier service in insulated transport boxes at a temperature of ±10°C to Senegal (±36 h of transport). Upon arrival in the insectary in Dakar, the pupae were transferred to an emergence room and the flies monitored for 3–6 days. Results The results showed that the used system of isothermal boxes that contained phase change material packs (S8) managed to keep the temperature at around 10°C which prevented male fly emergence during transport. The emergence rate was significantly higher for pupae from batch 2 (chilled at 4°C for one day in the source insectary before transport) than those from batch 1 (chilled at 4°C for two days in the source insectary before transport) i.e. an average (±sd) of 76.1 ± 13.2% and 72.2 ± 14.3%, respectively with a small proportion emerging during transport (0.7 ± 1.7% and 0.9 ± 2.9%, respectively). Among the emerged flies, the percentage with deformed (not fully expanded) wings was significantly higher for flies from batch 1 (12.0 ± 6.3%) than from batch 2 (10.7 ± 7.5%). The amount of sterile males available for release as a proportion of the total pupae shipped was 65.8 ± 13.3% and 61.7 ± 14.7% for batch 1 and 2 pupae, respectively. Conclusions The results also showed that the temperature inside the parcel must be controlled around 10°C with a maximal deviation of 3°C to maximize the male yield. Electronic supplementary material The online version of this article (doi:10.1186/s13071-015-0869-3) contains supplementary material, which is available to authorized users.

Background Tsetse flies transmit trypanosomes that cause human and African animal trypanosomosis, a debilitating disease of humans (sleeping sickness) and livestock (nagana). An area-wide integrated pest management campaign against Glossina palpalis gambiensis has been implemented in Senegal since 2010 that includes a sterile insect technique (SIT) component. The SIT can only be successful when the sterile males that are destined for release have a flight ability, survival and competitiveness that are as close as possible to that of their wild male counterparts. Methodology/Principal Findings Tests were developed to assess the quality of G. p. gambiensis males that emerged from pupae that were produced and irradiated in Burkina Faso and Slovakia (irradiation done in Seibersdorf, Austria) and transported weekly under chilled conditions to Dakar, Senegal. For each consignment a sample of 50 pupae was used for a quality control test (QC group). To assess flight ability, the pupae were put in a cylinder filtering emerged flies that were able to escape the cylinder. The survival of these flyers was thereafter monitored under stress conditions (without feeding). Remaining pupae were emerged and released in the target area of the eradication programme (RF group). The following parameter values were obtained for the QC flies: average emergence rate more than 69%, median survival of 6 days, and average flight ability of more than 35%. The quality protocol was a good proxy of fly quality, explaining a large part of the variances of the examined parameters. Conclusions/Significance The quality protocol described here will allow the accurate monitoring of the quality of shipped sterile male tsetse used in operational eradication programmes in the framework of the Pan-African Tsetse and Trypanosomosis Eradication Campaign., Author Summary An area-wide integrated pest management campaign against Glossina palpalis gambiensis has been implemented in Senegal since 2010 that includes a sterile insect technique component. The sterile males used for the releases emerged from pupae that were produced and irradiated in Burkina Faso and Slovakia (irradiation done in Seibersdorf, Austria) and transported weekly under chilled conditions to Dakar, Senegal. Tests were developed to assess the quality (flight ability and survival) of sterile males. To assess flight ability, for each consignment a sample of 50 pupae (QC flies) was put in a cylinder filtering emerged flies that were able to escape the cylinder. The survival of these flyers was monitored under stress conditions. Remaining pupae (RF flies) were emerged and released in the target area of the eradication programme. The quality assessment of the QC flies was a good proxy of the quality of the RF flies. The quality protocol described here will allow the accurate monitoring of the quality of shipped sterile tsetse males used in operational eradication programmes.

To identify molecular genetic markers of resistance or susceptibility to dermatophilosis in cattle, we used a functional candidate gene approach to analyse the DNA polymorphisms of targeted genes encoding molecules implicated in known mechanisms of both non-specific and specific immune responses existing in the pathogen/host interface mechanisms. The most significant results were obtained within the Major Histocompatibility Complex (MHC) where the BoLA-DRB3 and DQB genes encode molecules involved in the antigen presentation to T cell receptors. A unique particular BoLA class II haplotype, constituted by one DRB3 exon 2 allele and one DQB allele highly correlates with the susceptibility character (P < 0.001). This marker of susceptibility haplotype was also found and validated in other bovine populations. A eugenic marker assisted selection was developed in the field by eliminating only the animals having this haplotype of susceptibility. Then the disease prevalence was reduced from 0.76 to 0.02 over 5 years. A crossbreeding plan is in progress to study the genetic transmission of the genotypic and phenotypic characters of susceptibility to dermatophilosis. In conclusion, we discuss several hypothesis at the molecular and cellular levels to better define the exact role of the MHC molecules in the diseases control and to answer the question. how MHC diversity is selectively maintained by natural selection imposed by the pathogens? (Resume d'auteur)

Resistance to the drugs used to control African animal trypanosomosis is increasingly recognised as a constraint to livestock production in sub-Saharan Africa. The most commonly used tests for detection of trypanocidal drug resistance are tests using mice or ruminants, but these suffer from lack of standardisation and hence it may be difficult to compare the results of different investigators. Tests in mice are less expensive than tests in ruminants, but while tests in mice they may be useful as a general guide to resistance in a geographic area they should not be extrapolated to cattle on an individual trypanosome level. Moreover, the commonly used protocols are too laborious for their application to large number of trypanosome isolates on an area-wide basis. This paper presents guidelines for standardised testing of trypanocidal drugs in vivo, and introduces a simplified single-dose test for use in mice, which is convenient for use in areas with limited laboratory facilities. The single-dose test is appropriate for characterisation of geographic areas in terms of trypanocidal drug resistance using large numbers of trypanosome isolates, for making comparisons between areas, and for monitoring changes in trypanocidal drug resistance over time. Multiple-dose tests may be used to determine the degree of resistance of individual stabilates to be determined precisely in mice are also described, but for logistical reasons these will rarely be conducted on more than a few stabilates, and testing of a larger number of stabilates in the single-dose test will generally provide more useful information. Finally, we describe tests in cattle that may be used to determine the efficacy of recommended curative doses of trypanocidal drugs for the treatment of infection with individual trypanosome isolates, including Trypanosoma vivax, which is rarely infective for mice.

Lors d'une etude globale du risque trypanosomien menee dans la zone agropastorale de Sideradougou (Burkina Faso), des troupeaux sentinelles issus de deux systemes d'elevage differents ont ete suivis durant deux ans. L'incidence trypanosomienne mensuelle a ete mesuree et interpretee en fonction des parcours des troupeaux, de leur pratique d'abreuvement et de leur contact avec les glossines ripicoles (Glossina tachinoides et G. palpalis gambiensis). A Nakaka, village d'eleveurs Peuls, la transmission en saison seche est assuree aux points d'abreuvement perennes dans la galerie forestiere. En saison des pluies, les glossines ripicoles se dispersent dans les savanes et infectent les animaux jusque dans les villages. A Pefrou, ensemble de campements d'agriculteurs Bobo, les troupeaux sont composes essentiellement de boeufs de traction. Les animaux issus des campements localises a proximite du cours d'eau s'abreuvent dans les points d'eau des formations riveraines et sont infectes toute l'annee. L'incidence est plus elevee en hivernage et en debut de saison seche, periode ou les glossines sont les plus nombreuses. A l'oppose, les troupeaux des campements eloignes du reseau hydrographique (3 km) sont abreuves au puits et ne frequentent pas les biotopes des glossines. Dans ce paysage essentiellement agricole, les glossines ne se dispersent pas, meme en saison humide. L'incidence dans les troupeaux est quasiment nulle. Ces resultats montrent l'importance des interfaces spatiales et temporelles entre les bovins et les glossines dans l'epidemiologie des trypanosomoses en Afrique de l'ouest. (Resume d'auteur)