Search

Background: Human African trypanosomiasis is a parasitic disease caused by trypanosomes among which Trypanosoma brucei gambiense is responsible for a chronic form (gHAT) in West and Central Africa. Its elimination as a public health problem (EPHP) was targeted for 2020. Côte d'Ivoire was one of the first countries to be validated by WHO in 2020 and this was particularly challenging as the country still reported around a hundred cases a year in the early 2000s. This article describes the strategies implemented including a mathematical model to evaluate the reporting results and infer progress towards sustainable elimination. Methods: The control methods used combined both exhaustive and targeted medical screening strategies including the follow-up of seropositive subjects– considered as potential asymptomatic carriers to diagnose and treat cases– as well as vector control to reduce the risk of transmission in the most at-risk areas. A mechanistic model was used to estimate the number of underlying infections and the probability of elimination of transmission (EoT) was met between 2000–2021 in two endemic and two hypo-endemic health districts. Results: Between 2015 and 2019, nine gHAT cases were detected in the two endemic health districts of Bouaflé and Sinfra in which the number of cases/10,000 inhabitants was far below 1, a necessary condition for validating EPHP. Modelling estimated a slow but steady decline in transmission across the health districts, bolstered in the two endemic health districts by the introduction of vector control. The decrease in underlying transmission in all health districts corresponds to a high probability that EoT has already occurred in Côte d'Ivoire. Conclusion: This success was achieved through a multi-stakeholder and multidisciplinary one health approach where research has played a major role in adapting tools and strategies to this large epidemiological transition to a very low prevalence. This integrated approach will need to conti

La maladie du sommeil, ou trypanosomiase humaine africaine (THA), est due à Trypanosoma brucei transmis par la glossine ou mouche tsé-tsé. Après avoir ravagé l'Afrique subsaharienne dans la première moitié du XXe siècle, comme en témoigne l'extraordinaire ouvrage d'Alphonse Laveran et Félix Mesnil en 1912 (Trypanosomes et trypanosomiases), la THA, maladie tropicale négligée mortelle, dite " du bout de la piste " et pour laquelle il n'existe pas de vaccin, semble aujourd'hui à portée de main de l'élimination. Nous passons en revue les stratégies, activités et outils qui ont permis cette forte réduction du fardeau sanitaire pour les populations d'Afrique subsaharienne : environ 300 000 cas estimés dans les années 1990 contre moins de 1000 cas rapportés annuellement depuis 2018. La lutte contre la maladie du sommeil consiste principalement à dépister et traiter les cas ainsi qu'à lutter contre la glossine vectrice pour casser le cycle de transmission. En passant en 30 ans d'un contexte épidémique à un contexte d'élimination, la maladie du sommeil a subi une transition épidémiologique sans précédent à laquelle les stratégies et les outils de lutte ont dû s'adapter. Nous montrons comment la recherche a soutenu ces efforts et examinons certains des défis restants pour rendre effective et durable son élimination.

Vector-borne diseases affecting livestock have serious impacts in Africa. Trypanosomosis is caused by parasites transmitted by tsetse flies and other blood-sucking Diptera. The animal form of the disease is a scourge for African livestock keepers, is already present in Latin America and Asia, and has the potential to spread further. A human form of the disease also exists, known as human African trypanosomosis or sleeping sickness. Controlling and progressively minimizing the burden of animal trypanosomosis (COMBAT) is a four-year research and innovation project funded by the European Commission, whose ultimate goal is to reduce the burden of animal trypanosomosis (AT) in Africa. The project builds on the progressive control pathway (PCP), a risk-based, step-wise approach to disease reduction or elimination. COMBAT will strengthen AT control and prevention by improving basic knowledge of AT, developing innovative control tools, reinforcing surveillance, rationalizing control strategies, building capacity, and raising awareness. Knowledge gaps on disease epidemiology, vector ecology and competence, and biological aspects of trypanotolerant livestock will be addressed. Environmentally friendly vector control technologies and more effective and adapted diagnostic tools will be developed. Surveillance will be enhanced by developing information systems, strengthening reporting, and mapping and modelling disease risk in Africa and beyond. The socio-economic burden of AT will be assessed at a range of geographical scales. Guidelines for the PCP and harmonized national control strategies and roadmaps will be developed. Gender equality and ethics will be pivotal in all project activities. The COMBAT project benefits from the expertise of African and European research institutions, national veterinary authorities, and international organizations. The project consortium comprises 21 participants, including a geographically balanced representation from 13 African countries, and

Vector-borne diseases affecting livestock have serious impacts in Africa. Trypanosomosis is caused by parasites transmitted by tsetse flies and other blood-sucking Diptera. The animal form of the disease is a scourge for African livestock keepers, is already present in Latin America and Asia, and has the potential to spread further. A human form of the disease also exists, known as human African trypanosomosis or sleeping sickness. Controlling and progressively minimizing the burden of animal trypanosomosis (COMBAT) is a four-year research and innovation project funded by the European Commission, whose ultimate goal is to reduce the burden of animal trypanosomosis (AT) in Africa. The project builds on the progressive control pathway (PCP), a risk-based, step-wise approach to disease reduction or elimination. COMBAT will strengthen AT control and prevention by improving basic knowledge of AT, developing innovative control tools, reinforcing surveillance, rationalizing control strategies, building capacity, and raising awareness. Knowledge gaps on disease epidemiology, vector ecology and competence, and biological aspects of trypanotolerant livestock will be addressed. Environmentally friendly vector control technologies and more effective and adapted diagnostic tools will be developed. Surveillance will be enhanced by developing information systems, strengthening reporting, and mapping and modelling disease risk in Africa and beyond. The socio-economic burden of AT will be assessed at a range of geographical scales. Guidelines for the PCP and harmonized national control strategies and roadmaps will be developed. Gender equality and ethics will be pivotal in all project activities. The COMBAT project benefits from the expertise of African and European research institutions, national veterinary authorities, and international organizations. The project consortium comprises 21 participants, including a geographically balanced representation from 13 African countries, and

Vector-borne diseases affecting livestock have serious impacts in Africa. Trypanosomosis is caused by parasites transmitted by tsetse flies and other blood-sucking Diptera. The animal form of the disease is a scourge for African livestock keepers, is already present in Latin America and Asia, and has the potential to spread further. A human form of the disease also exists, known as human African trypanosomosis or sleeping sickness. Controlling and progressively minimizing the burden of animal trypanosomosis (COMBAT) is a four-year research and innovation project funded by the European Commission, whose ultimate goal is to reduce the burden of animal trypanosomosis (AT) in Africa. The project builds on the progressive control pathway (PCP), a risk-based, step-wise approach to disease reduction or elimination. COMBAT will strengthen AT control and prevention by improving basic knowledge of AT, developing innovative control tools, reinforcing surveillance, rationalizing control strategies, building capacity, and raising awareness. Knowledge gaps on disease epidemiology, vector ecology and competence, and biological aspects of trypanotolerant livestock will be addressed. Environmentally friendly vector control technologies and more effective and adapted diagnostic tools will be developed. Surveillance will be enhanced by developing information systems, strengthening reporting, and mapping and modelling disease risk in Africa and beyond. The socio-economic burden of AT will be assessed at a range of geographical scales. Guidelines for the PCP and harmonized national control strategies and roadmaps will be developed. Gender equality and ethics will be pivotal in all project activities. The COMBAT project benefits from the expertise of African and European research institutions, national veterinary authorities, and international organizations. The project consortium comprises 21 participants, including a geographically balanced representation from 13 African countries, and

Gambiense human African trypanosomiasis (g-HAT) is the chronic form of sleeping sickness caused by Trypanosoma brucei gambiense in West and Central Africa, while Trypanosoma bru- cei rhodesiense causes an acute form in eastern Africa. g-HAT is targeted for elimination as a public health problem by 2020 and 0 transmission by 2030. Control of g-HAT is largely based on identification and treatment of infected individuals, supplemented by control of the tsetse fly vectors. There has been growing evidence that when both tsetse control and case identification activities are carried out simultaneously in the same geographies, elimination of the disease is accelerated. Here, we describe how the Trypa-NO! Partnership is using novel and classical tools to drive g-HAT elimination in an integrated approach, progress made, lessons learnt, and future directions.

Introduction : Les trypanosomoses africaines sont transmises par la mouche tsé-tsé aux humains et au bétail. En Côte d'Ivoire, la Trypanosomiase Humaine Africaine (THA) sévit principalement dans la région de la Marahoué, sous forme de foyers où sévit également la Trypanosomose Animale Africaine (TAA). Cependant, le réservoir animal à T.b.gambiense, qui intervient probablement dans le cycle pathogène de la maladie chez l'homme, n'a jamais été pris en compte dans la lutte contre la THA en Côte d'Ivoire. Matériel et méthodes : Dans le but de mener une lutte durable, des enquêtes géographiques, entomologiques et parasitologiques de bases ont été menées dans le foyer de THA de Sinfra ; et des actions de lutte combinées et intégrées ciblant les humains, les tsé-tsé, le bétail et les porcs domestiques ont été proposées. Résultats : Les plus fortes densités de Glossina palpalis palpalis, ont été trouvées dans et autour des villages où les porcs villageois en divagation sont présents. Ces porcs sont les plus infectés de tous les animaux par des trypanosomes (85,7%) et constituent l'alimentation préférée des tsé-tsé (87%). Conclusion: Les animaux domestiques comme les porcs pourraient jouer un rôle dans l'épidémiologie de la THA. Cela suggère leur prise en compte dans les stratégies de lutte basées sur le concept one health, dans un contexte d'élimination durable.

Introduction En Côte d'Ivoire, la région de Méagui a été mise en valeur tardivement, mais elle affiche des densités de population pouvant atteindre plus de 400 hab/km2. Dans cette région, parallèlement aux fortes densités de population humaine, il a été mis en évidence une disparition des glossines sur de vastes superficies. On suspecte l'impact de l'anthropisation sur la disparition des glossines, et notamment l'utilisation massive de pesticides. Matériels et méthodes Nous avons cherché à déterminer les modalités d'utilisation des pesticides (produits, quantité, fréquence) dans une zone allant de la ville de Méagui jusqu'au parc national de Tai. Pour cela, à l'aide du GPS, nous avons délimité 100 parcelles de cultures (cacao-café, hévéa, riz, maraicher) traitées avec des pesticides. Un questionnaire sur les modalités d'utilisation des pesticides a été soumis aux paysans propriétaires des parcelles délimitées. Résultats Au total, 74 pesticides différents ont été cités par les paysans, parmi lesquels 48 insecticides et 26 herbicides. En moyenne, la fréquence de pulvérisation des parcelles à l'aide de pesticides est estimée à 3 fois dans l'année. L'ensemble des parcelles enquêtées, d'une superficie totale de 335 hectares, reçoit une application annuelle de 1623 litres de pesticides (4,8 l/hectare). L'insecticide le plus utilisé par les paysans est la grosudine dont la substance active contient la bifenthrine appartenant à la famille des pyréthrinoides de synthèse. Conclusion Les modalités d'épandage de pesticides adoptées par les paysans ont probablement des conséquences sur les densités de glossines et donc sur le risque des trypanosomoses.

Introduction En Côte d'Ivoire, la région de Méagui a été mise en valeur tardivement, mais elle affiche des densités de population pouvant atteindre plus de 400 hab/km2. Dans cette région, parallèlement aux fortes densités de population humaine, il a été mis en évidence une disparition des glossines sur de vastes superficies. On suspecte l'impact de l'anthropisation sur la disparition des glossines, et notamment l'utilisation massive de pesticides. Matériels et méthodes Nous avons cherché à déterminer les modalités d'utilisation des pesticides (produits, quantité, fréquence) dans une zone allant de la ville de Méagui jusqu'au parc national de Tai. Pour cela, à l'aide du GPS, nous avons délimité 100 parcelles de cultures (cacao-café, hévéa, riz, maraicher) traitées avec des pesticides. Un questionnaire sur les modalités d'utilisation des pesticides a été soumis aux paysans propriétaires des parcelles délimitées. Résultats Au total, 74 pesticides différents ont été cités par les paysans, parmi lesquels 48 insecticides et 26 herbicides. En moyenne, la fréquence de pulvérisation des parcelles à l'aide de pesticides est estimée à 3 fois dans l'année. L'ensemble des parcelles enquêtées, d'une superficie totale de 335 hectares, reçoit une application annuelle de 1623 litres de pesticides (4,8 l/hectare). L'insecticide le plus utilisé par les paysans est la grosudine dont la substance active contient la bifenthrine appartenant à la famille des pyréthrinoides de synthèse. Conclusion Les modalités d'épandage de pesticides adoptées par les paysans ont probablement des conséquences sur les densités de glossines et donc sur le risque des trypanosomoses.

Introduction : Les trypanosomoses africaines sont transmises par la mouche tsé-tsé aux humains et au bétail. En Côte d'Ivoire, la Trypanosomiase Humaine Africaine (THA) sévit principalement dans la région de la Marahoué, sous forme de foyers où sévit également la Trypanosomose Animale Africaine (TAA). Cependant, le réservoir animal à T.b.gambiense, qui intervient probablement dans le cycle pathogène de la maladie chez l'homme, n'a jamais été pris en compte dans la lutte contre la THA en Côte d'Ivoire. Matériel et méthodes : Dans le but de mener une lutte durable, des enquêtes géographiques, entomologiques et parasitologiques de bases ont été menées dans le foyer de THA de Sinfra ; et des actions de lutte combinées et intégrées ciblant les humains, les tsé-tsé, le bétail et les porcs domestiques ont été proposées. Résultats : Les plus fortes densités de Glossina palpalis palpalis, ont été trouvées dans et autour des villages où les porcs villageois en divagation sont présents. Ces porcs sont les plus infectés de tous les animaux par des trypanosomes (85,7%) et constituent l'alimentation préférée des tsé-tsé (87%). Conclusion: Les animaux domestiques comme les porcs pourraient jouer un rôle dans l'épidémiologie de la THA. Cela suggère leur prise en compte dans les stratégies de lutte basées sur le concept one health, dans un contexte d'élimination durable.

Background: Glossina palpalis palpalis (G. p. palpalis) is one of the principal vectors of sleeping sickness and nagana in Africa with a geographical range stretching from Liberia in West Africa to Angola in Central Africa. It inhabits tropical rain forest but has also adapted to urban settlements. We set out to standardize a long-lasting, practical and cost-effective visually attractive device that would induce the strongest landing response by G. p. palpalis for future use as an insecticide impregnated tool in area-wide population suppression of this fly across its range. Methodology/Principal Findings: Trials were conducted in wet and dry seasons in the Ivory Coast, Cameroon, the Democratic Republic of Congo and Angola to measure the performance of traps (biconical, monoconical and pyramidal) and targets of different sizes and colours, with and without chemical baits, at different population densities and under different environmental conditions. Adhesive film was used as a practical enumerator at these remote locations to compare landing efficiencies of devices. Independent of season and country, both phthalogen blue-black and blue-black-blue 1 m2 targets covered with adhesive film proved to be as good as traps in phthalogen blue or turquoise blue for capturing G. p. palpalis. Trap efficiency varied (8–51%). There was no difference between the performance of blue-black and blue-blackblue 1 m2 targets. Baiting with chemicals augmented the overall performance of targets relative to traps. Landings on smaller phthalogen blue-black 0.25 m2 square targets were not significantly different from either 1 m2 blue-black-blue or blue-black square targets. Three times more flies were captured per unit area on the smaller device. Conclusions/Significance:Blue-black 0.25 m2 cloth targets show promise as simple cost effective devices for management of G. p. palpalis as

Modern methods allow a geometric representation of forms, separating size and shape. In entomology, as well as in many other fields involving arthropod studies, shape variation has proved useful for species identification and population characterization. In medical entomology, it has been applied to very specific questions such as population structure, reinfestation of insecticide-treated areas and cryptic species recognition. For shape comparisons, great importance is given to the quality of landmarks in terms of comparability. Two conceptually and statistically separate approaches are: (i) landmark-based morphometrics, based on the relative position of a few anatomical “true” or “traditional” landmarks, and (ii) outline-based morphometrics, which captures the contour of forms through a sequence of close “pseudo-landmarks”. Most of the studies on insects of medical, veterinary or economic importance make use of the landmark approach. The present survey makes a case for the outline method, here based on elliptic Fourier analysis. The collection of pseudo-landmarks may require the manual digitization of many points and, for this reason, might appear less attractive. It, however, has the ability to compare homologous organs or structures having no landmarks at all. This strength offers the possibility to study a wider range of anatomical structures and thus, a larger range of arthropods. We present a few examples highlighting its interest for separating close or cryptic species, or characterizing conspecific geographic populations, in a series of different vector organisms. In this simple application, i.e. the recognition of close or cryptic forms, the outline approach provided similar scores as those obtained by the landmark-based approach.

Modern methods allow a geometric representation of forms, separating size and shape. In entomology, as well as in many other fields involving arthropod studies, shape variation has proved useful for species identification and population characterization. In medical entomology, it has been applied to very specific questions such as population structure, reinfestation of insecticide-treated areas and cryptic species recognition. For shape comparisons, great importance is given to the quality of landmarks in terms of comparability. Two conceptually and statistically separate approaches are: (i) landmark-based morphometrics, based on the relative position of a few anatomical “true” or “traditional” landmarks, and (ii) outline-based morphometrics, which captures the contour of forms through a sequence of close “pseudo-landmarks”. Most of the studies on insects of medical, veterinary or economic importance make use of the landmark approach. The present survey makes a case for the outline method, here based on elliptic Fourier analysis. The collection of pseudo-landmarks may require the manual digitization of many points and, for this reason, might appear less attractive. It, however, has the ability to compare homologous organs or structures having no landmarks at all. This strength offers the possibility to study a wider range of anatomical structures and thus, a larger range of arthropods. We present a few examples highlighting its interest for separating close or cryptic species, or characterizing conspecific geographic populations, in a series of different vector organisms. In this simple application, i.e. the recognition of close or cryptic forms, the outline approach provided similar scores as those obtained by the landmark-based approach.

Background: Because of its high sensitivity and its ease of use in the field, the card agglutination test for trypanosomiasis (CATT) is widely used for mass screening of sleeping sickness. However, the CATT exhibits false-positive results (i) raising the question of whether CATT-positive subjects who are negative in parasitology are truly exposed to infection and (ii) making it difficult to evaluate whether Trypanosoma brucei (T.b.) gambiense is still circulating in areas of low endemicity. The objective of this study was to assess the value of the immune trypanolysis test (TL) in characterising the HAT status of CATT-positive subjects and to monitor HAT elimination in West Africa. Methodology/Principal Findings: TL was performed on plasma collected from CATT-positive persons identified within medical surveys in several West African HAT foci in Guinea, Co¿ te d'Ivoire and Burkina Faso with diverse epidemiological statuses (active, latent, or historical). All HAT cases were TL+. All subjects living in a nonendemic area were TL2. CATT prevalence was not correlated with HAT prevalence in the study areas, whereas a significant correlation was found using TL. Conclusion and Significance: TL appears to be a marker for contact with T.b. gambiense. TL can be a tool (i) at an individual level to identify nonparasitologically confirmed CATT-positive subjects as well as those who had contact with T.b. gambiense and should be followed up, (ii) at a population level to identify priority areas for intervention, and (iii) in the context of HAT elimination to identify areas free of HAT.

Background: The Government of Senegal has initiated the ''Projet de lutte contre les glossines dans les Niayes'' to remove the trypanosomosis problem from this area in a sustainable way. Due to past failures to sustainably eradicate Glossina palpalis gambiensis from the Niayes area, controversies remain as to the best strategy implement, i.e. ''eradication'' versus ''suppression.'' To inform this debate, we used population genetics to measure genetic differentiation between G. palpalis gambiensis from the Niayes and those from the southern tsetse belt (Missira). Methodology/Principal Findings: Three different markers (microsatellite DNA, mitochondrial CO1 DNA, and geometric morphometrics of the wings) were used on 153 individuals and revealed that the G. p. gambiensis populations of the Niayes were genetically isolated from the nearest proximate known population of Missira. The genetic differentiation measured between these two areas (h = 0.12 using microsatellites) was equivalent to a between-taxa differentiation. We also demonstrated that within the Niayes, the population from Dakar - Hann was isolated from the others and had probably experienced a bottleneck. Conclusion/Significance: The information presented in this paper leads to the recommendation that an eradication strategy for the Niayes populations is advisable. This kind of study may be repeated in other habitats and for other tsetse species to (i) help decision on appropriate tsetse control strategies and (ii) find other possible discontinuities in tsetse distribution.

Background: Because of its high sensitivity and its ease of use in the field, the card agglutination test for trypanosomiasis (CATT) is widely used for mass screening of sleeping sickness. However, the CATT exhibits false-positive results (i) raising the question of whether CATT-positive subjects who are negative in parasitology are truly exposed to infection and (ii) making it difficult to evaluate whether Trypanosoma brucei (T.b.) gambiense is still circulating in areas of low endemicity. The objective of this study was to assess the value of the immune trypanolysis test (TL) in characterising the HAT status of CATT-positive subjects and to monitor HAT elimination in West Africa. Methodology/Principal Findings: TL was performed on plasma collected from CATT-positive persons identified within medical surveys in several West African HAT foci in Guinea, Co¿ te d'Ivoire and Burkina Faso with diverse epidemiological statuses (active, latent, or historical). All HAT cases were TL+. All subjects living in a nonendemic area were TL2. CATT prevalence was not correlated with HAT prevalence in the study areas, whereas a significant correlation was found using TL. Conclusion and Significance: TL appears to be a marker for contact with T.b. gambiense. TL can be a tool (i) at an individual level to identify nonparasitologically confirmed CATT-positive subjects as well as those who had contact with T.b. gambiense and should be followed up, (ii) at a population level to identify priority areas for intervention, and (iii) in the context of HAT elimination to identify areas free of HAT.

Background: The Government of Senegal has initiated the ''Projet de lutte contre les glossines dans les Niayes'' to remove the trypanosomosis problem from this area in a sustainable way. Due to past failures to sustainably eradicate Glossina palpalis gambiensis from the Niayes area, controversies remain as to the best strategy implement, i.e. ''eradication'' versus ''suppression.'' To inform this debate, we used population genetics to measure genetic differentiation between G. palpalis gambiensis from the Niayes and those from the southern tsetse belt (Missira). Methodology/Principal Findings: Three different markers (microsatellite DNA, mitochondrial CO1 DNA, and geometric morphometrics of the wings) were used on 153 individuals and revealed that the G. p. gambiensis populations of the Niayes were genetically isolated from the nearest proximate known population of Missira. The genetic differentiation measured between these two areas (h = 0.12 using microsatellites) was equivalent to a between-taxa differentiation. We also demonstrated that within the Niayes, the population from Dakar - Hann was isolated from the others and had probably experienced a bottleneck. Conclusion/Significance: The information presented in this paper leads to the recommendation that an eradication strategy for the Niayes populations is advisable. This kind of study may be repeated in other habitats and for other tsetse species to (i) help decision on appropriate tsetse control strategies and (ii) find other possible discontinuities in tsetse distribution.

Human African trypanosomiasis, or sleeping sickness caused by Trypanosoma brucei gambiense, occurs in Western and Central Africa. T. brucei s.l. displays a huge diversity of adaptations and host specificities, and questions about its reproductive mode, dispersal abilities, and effective size remain under debate. We have investigated genetic variation at 8 microsatellite loci of T. b. gambiense strains isolated from human African trypanosomiasis patients in the Ivory Coast and Guinea, with the aim of knowing how genetic information was partitioned within and between individuals in both temporal and spatial scales. The results indicate that (i) migration of T. b. gambiense group 1 strains does not occur at the scale of West Africa, and that even at a finer scale (e.g., within Guinea) migration is restricted; (ii) effective population sizes of trypanosomes, as reflected by infected hosts, are probably higher than what the epidemiological surveys suggest; and (iii) T. b. gambiense group 1 is most likely a strictly clonally reproducing organism.

La Guinée est actuellement le pays d'Afrique de l'Ouest le plus touché par la maladie du sommeil, en particulier la région littorale des mangroves où le vecteur est Glossina palpalis gambiensis, notamment au niveau des foyers de Dubréka et Boffa. Les îles de Loos constituent un petit archipel à 5 km de la capitale Conakry. Au cours des enquêtes épidémiologiques menées sur les vecteurs, les hôtes humains et animaux en octobre-novembre 2006, nous n'avons pas mis en évidence de trypanosomes pathogènes. Toutefois, les fortes densités de tsé-tsé (jusqu'à plus de 100 mouches/piège/jour), associées spatialement aux élevages de porcs, constituent un véritable risque pour les humains au vu des nombreux mouvements de populations entre ces îles et les foyers voisins de mangrove, ainsi qu'au vu de l'historique de la maladie du sommeil sur ces îles. Il existe également un fort risque de trypanosomose pour l'activité d'élevage de porcs. Enfin, ces îles constituent l'un des principaux lieux touristiques de la région. Cette situation, combinée à la possibilité d'une élimination définitive, a conduit le Programme national de lutte contre la trypanosomose humaine africaine à envisager pour la première fois en Afrique de l'Ouest un programme d'élimination des tsé-tsé de ces îles, basé sur une stratégie "area wide", ce qui participe à l'objectif global de la PATTEC (Campagne panafricaine d'éradication des tsé-tsé et des trypanosomoses).

Human African trypanosomiasis, or sleeping sickness caused by Trypanosoma brucei gambiense, occurs in Western and Central Africa. T. brucei s.l. displays a huge diversity of adaptations and host specificities, and questions about its reproductive mode, dispersal abilities, and effective size remain under debate. We have investigated genetic variation at 8 microsatellite loci of T. b. gambiense strains isolated from human African trypanosomiasis patients in the Ivory Coast and Guinea, with the aim of knowing how genetic information was partitioned within and between individuals in both temporal and spatial scales. The results indicate that (i) migration of T. b. gambiense group 1 strains does not occur at the scale of West Africa, and that even at a finer scale (e.g., within Guinea) migration is restricted; (ii) effective population sizes of trypanosomes, as reflected by infected hosts, are probably higher than what the epidemiological surveys suggest; and (iii) T. b. gambiense group 1 is most likely a strictly clonally reproducing organism.

La Guinée est actuellement le pays d'Afrique de l'Ouest le plus touché par la maladie du sommeil, en particulier la région littorale des mangroves où le vecteur est Glossina palpalis gambiensis, notamment au niveau des foyers de Dubréka et Boffa. Les îles de Loos constituent un petit archipel à 5 km de la capitale Conakry. Au cours des enquêtes épidémiologiques menées sur les vecteurs, les hôtes humains et animaux en octobre-novembre 2006, nous n'avons pas mis en évidence de trypanosomes pathogènes. Toutefois, les fortes densités de tsé-tsé (jusqu'à plus de 100 mouches/piège/jour), associées spatialement aux élevages de porcs, constituent un véritable risque pour les humains au vu des nombreux mouvements de populations entre ces îles et les foyers voisins de mangrove, ainsi qu'au vu de l'historique de la maladie du sommeil sur ces îles. Il existe également un fort risque de trypanosomose pour l'activité d'élevage de porcs. Enfin, ces îles constituent l'un des principaux lieux touristiques de la région. Cette situation, combinée à la possibilité d'une élimination définitive, a conduit le Programme national de lutte contre la trypanosomose humaine africaine à envisager pour la première fois en Afrique de l'Ouest un programme d'élimination des tsé-tsé de ces îles, basé sur une stratégie "area wide", ce qui participe à l'objectif global de la PATTEC (Campagne panafricaine d'éradication des tsé-tsé et des trypanosomoses).

Background: Glossina palpalis palpalis (G. p. palpalis) is one of the principal vectors of sleeping sickness and nagana in Africa with a geographical range stretching from Liberia in West Africa to Angola in Central Africa. It inhabits tropical rain forest but has also adapted to urban settlements. We set out to standardize a long-lasting, practical and cost-effective visually attractive device that would induce the strongest landing response by G. p. palpalis for future use as an insecticide impregnated tool in area-wide population suppression of this fly across its range. Methodology/Principal Findings: Trials were conducted in wet and dry seasons in the Ivory Coast, Cameroon, the Democratic Republic of Congo and Angola to measure the performance of traps (biconical, monoconical and pyramidal) and targets of different sizes and colours, with and without chemical baits, at different population densities and under different environmental conditions. Adhesive film was used as a practical enumerator at these remote locations to compare landing efficiencies of devices. Independent of season and country, both phthalogen blue-black and blue-black-blue 1 m2 targets covered with adhesive film proved to be as good as traps in phthalogen blue or turquoise blue for capturing G. p. palpalis. Trap efficiency varied (8–51%). There was no difference between the performance of blue-black and blue-blackblue 1 m2 targets. Baiting with chemicals augmented the overall performance of targets relative to traps. Landings on smaller phthalogen blue-black 0.25 m2 square targets were not significantly different from either 1 m2 blue-black-blue or blue-black square targets. Three times more flies were captured per unit area on the smaller device. Conclusions/Significance:Blue-black 0.25 m2 cloth targets show promise as simple cost effective devices for management of G. p. palpalis as