BackgroundHuman and Animal Trypanosomes are major problems for the socio-economic growth of developing countries like Burkina Faso. Ivermectin is currently used to treat humans in mass drug administration programs in Africa, and is also commonly used for veterinary purposes. In this study, we tested the effect of ivermectin injected into cattle on the survival and fecundity of Glossina palpalis gambiensis, the main vector of human and animal trypanosomes in West Africa.MethodsThree cows (local zebu*baoulé crossbreds) were used, and received either no ivermectin (for the control), or ivermectin at therapeutic dose (0.2 mg/kg) and 10 times the therapeutic dose (2 mg/kg) respectively. G. palpalis gambiensis were fed on the cattle for their first bloodmeal, and then either on cattle or on membrane for subsequent meals.ResultsOur results showed that survival of Glossina palpalis gambiensis was significantly decreased when they were fed on cattle treated with ivermectin. This decrease in survival ranged from 21% to 83.7% for the therapeutic dose (0.2 mg/kg), up to 8 days after treatment. The effects of a dose of 2 mg/kg were higher with a 78.3% to 93.9% decrease in survival, until 14 days after injection. The therapeutic dose of ivermectin also decreased fecundity, and delayed the first larviposition, but there was no significant effect on hatching rate.ConclusionIvermectin injected into cattle may constitute an additional potential tool for the control of Glossina palpalis gambiensis and possibly other vector species. Further studies will be needed to assess its effect on trypanosome transmission, and to define more precisely the adequate dose to be used for control purposes.

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

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.

Background Domesticated animals play a role in maintaining residual transmission of Plasmodium parasites of humans, by offering alternative blood meal sources for malaria vectors to survive on. However, the blood of animals treated with veterinary formulations of the anti-helminthic drug ivermectin can have an insecticidal effect on adult malaria vector mosquitoes. This study therefore assessed the effects of treating cattle with long-acting injectable formulations of ivermectin on the survival of an important malaria vector species, to determine whether it has potential as a complementary vector control measure. Methods Eight head of a local breed of cattle were randomly assigned to either one of two treatment arms (2 × 2 cattle injected with one of two long-acting formulations of ivermectin with the BEPO® technology at the therapeutic dose of 1.2 mg/kg), or one of two control arms (2 × 2 cattle injected with the vehicles of the formulations). The lethality of the formulations was evaluated on 3–5-day-old Anopheles coluzzii mosquitoes through direct skin-feeding assays, from 1 to 210 days after treatment. The efficacy of each formulation was evaluated and compared using Cox proportional hazards survival models, Kaplan–Meier survival estimates, and log-logistic regression on cumulative mortality. Results Both formulations released mosquitocidal concentrations of ivermectin until 210 days post-treatment (hazard ratio > 1). The treatments significantly reduced mosquito survival, with average median survival time of 4–5 days post-feeding. The lethal concentrations to kill 50% of the Anopheles (LC50) before they became infectious (10 days after an infectious blood meal) were maintained for 210 days post-injection for both formulations. Conclusions This long-lasting formulation of ivermectin injected in cattle could complement insecticide-treated nets by suppressing field populations of zoophagic mosquitoes that are responsible, at least in part, for residual malaria transmission. The impact of this approach will of course depend on the field epidemiological context. Complementary studies will be necessary to characterize ivermectin withdrawal times and potential environmental toxicity. Graphical Abstract

Context: In 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. Methods: Eight 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. Results: The 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. Conclusion: Our 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. Key Words : Anopheles, malaria, residual transmission, Ivermectin, Long lasting formulation, cattle, One-health, Burkina Faso

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 Government have 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 need, which must hinge on harmonized, spatially-explicit information on the occurrence of AAT and its vectors.MethodsA digital repository containing tsetse and AAT data collected in Burkina Faso between 1990 and 2019 was assembled. 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 trap. When this was not possible, mapping done was at the level of site or location. Epidemiological data on AAT were mapped at the level of location/village.ResultsEntomological data showed that presence of four tsetse species in Burkina Faso. Glossina tachinoides was the most widespread and abundant species (56.35% of the catches), present from the eastern to the western part of the country. 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 (6.11%), with a patchy distribution in the southern parts of the country. One only cluster of G. medicorum was detected (less than 0.1%), located in the Southwest. 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 species 6.11±21.56% and 5.19±18.97% respectively), and to a lesser extend T. brucei infections (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 to aid the targeting of 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.

Fasciolosis is a major zoonosis of ruminants which causes great economic losses to breeders. Given the economic and public health importance of this pathology, it is necessary to establish the current situation in a perspective of animal and ruminant meat consumer health protection. Therefore, the present study was conducted at the slaughterhouse of Dédougou in order to identify the species of fluke that caused this pathology in the Boucle du Mouhoun region and to estimate the prevalence, the risk factors and the economic losses associated with this pathology. For this purpose, 820 cattle and 6360 small ruminants were diagnosed through post-mortem examination over a five-month period from March to August 2018. Out of the 6360 small ruminant livers examined, no cases of infestation were observed unlike cattle in which the prevalence of infestation was 2.07%. These infestations were all due to Fasciola gigantica. Regarding the risk factors, a slight effect of the month and a high influence of animals' origin were observed. March, with a prevalence of 0.25%, was the most favorable infestation month (P-value=0.05) and Sourou (19.51%), was the highest infestation risk area (P-value<0.0001). The estimated financial loss associated with the infestations was XOF 22,200.29 per infested animal. The situation is particularly worrying insofar as some populations, especially rural populations, consume meat from uncontrolled slaughter areas. Appropriate precautions should therefore be taken to ensure both consumer and animal health, given the zoonotic nature of the disease.

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