Effet d'une complémentation azotée sur la pathologie de la trypanosomose animale africaine chez les moutons sahéliens

Effect of a Complementation Nitrogenized on the Pathology of Animal Trypanosomiasis at the Sahelian Sheeps. La méthode thermique pour la détermination de flux de sève et la chambre à pression pour mesurer les potentiels hydriques foliaire et xylémique, ont été utilisées chez l'olivier de table Olea europaea cv Meski pour estimer la conductance hydraulique et la participation élémentaire des 4 branches selon l'orientation et l'exposition aux radiations solaires. Les mesures ont été effectuées du 23-10-2004 au 30-11-2004 dans un verger d'olivier de table et principalement sur deux arbres de la variété la plus commercialisée Meski. Cette étude a permis l'estimation de la conductance globale de la plante ainsi que la contribution de chaque génératrice. Les taux des conductances hydrauliques partielles sont respectivement de 43, 24, 20 et 13% dans les branches est, nord, sud et ouest. Elle a montré l'importance de l'interception lumineuse dans le déterminisme des flux de sève et des potentiels hydriques foliaires dans chaque branche, et par conséquent la liaison avec le mode de taille et la densité de plantation à préconiser

Influence d'une infection expérimentale à Trypanosoma congolense sur la fonction sexuelle des béliers Djallonké et Sahéliens en zone subhumide

Influence of an experimental Trypanosoma congolense infection on the reproductive function of Djallonké and Sahelian rams in subhumid zone. To measure the effect of African animal trypanosomosis (AAT) on male reproductive function, eight 18-24 month old Djallonké (ID; 31.2 ± 2.95 kg) and Sahelian (IS; 41.7 ± 4.64 kg) rams were infected with 104 Trypanosoma congolense. Eight other Djallonké (CD) and Sahelian (CS) rams with similar bodyweight and ages were used as uninfected controls. Four weeks after infection, ID and IS were treated with a trypanocidal drug, while maintained under observation. The evolution of clinical parameters shows a higher aptitude of Djallonké than Sahelian to control the effects of infection. This interbreed difference in susceptibility to AAT was confirmed by the higher weight losses in IS (-31.3 g) when compared to ID (-12.8 g) as to CD and CS rams. The effect of a T. congolense infection consisted in a decreased libido in IS (33 s) when compared to ID (22.1 s) (P > 0.05). The results indicate a significant effect of breed on ejaculate volume (CS: 1.23 ml vs CD: 0.88 ml; P < 0.05). Otherwise, breed did not significantly affect the other spermatic parameters. CD sperm cells concentration (3,293.4 x 106.ml-1), total abnormality rate (15.3%), dead sperm cells rate (13.9%), mobile sperm cells rate (75.5%), individual (3.76) and mass motilities (3.94) did not differ (P > 0.05) from those of CS (respectively 3,481.7 x 106.ml-1; 17.3%; 12.4%; 74.9%; 3.77; 3.36). However, the later produced 26% more total sperm cells than CD (P > 0.05). The infection reduced ejaculate volume by 15.8 and 14.5%, (P > 0.05), production of total sperm cells by 18.2 and 13.3% (P > 0.05) and the rate of mobile sperm cells by 14.2 and 27.9% (P < 0.05) respectively for Djallonké and Sahelian rams. The results show a dysfunctional state of testicles due to the harmful effects of AAT infection, hence the increase in dead sperm cells by 69.8 and 74.3% (P > 0.05) and in the rate of total abnormal sperm cells by 23.6 and 24.1% (P > 0.05) respectively for ID and IS rams when compared respectively to CD and CS animals. Harmful effects often more pronounced in Sahelian breeds during this experiment could indicate a higher susceptibility of this breed to AAT in comparison with Djallonké. One Sahelian ram died two weeks post-infection and azoospermia was observed in another one six weeks after chemotherapy and the disappearance of parasites from the bloodstream

Decrease in survival and fecundity of Glossina palpalis gambiensis vanderplank 1949 (Diptera : Glossinidae) fed on cattle treated with single doses of ivermectin

Background: Human 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. Methods: Three cows (local zebu*baoule 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. Results: Our 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. Conclusion: Ivermectin 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

Réseau d'EpidémioSurveillance de la Chimiorésistance aux trypanocides et aux acaricides en Afrique de l'Ouest (RESCAO)

Epidemiological Monitoring Network of Chemoresistance to Trypanocidal and Acaricides Drugs in West Africa (RESCAO). To better coordinate the efforts against trypanocidal and acaricides drugs resistance, the Institute of Tropical Medicine (ITM) of Antwerp and the "Centre International de Recherche-Développement sur l'Elevage en zone Subhumide (CIRDES)" of Bobo Dioulasso, established in April 2009 an epidemiological surveillance network of chemoresistance to trypanocidal and acaricides drugs in Western Africa, named RESCAO. Its main objective is to contribute to the improvement of the livestock health and of the productivity of agriculture in tropical Africa, through both an efficient strategic control of trypanosomosis and tick born diseases, including a rational use of the available therapeutic drugs. RESCAO is headed by a regional steering committee based at CIRDES. This committee meets on a yearly basis to overview the on-going activities and to identify new strategies for action. Moreover, molecular analyzes performed on samples from seven West African's countries, members of RESCAO, have shown that resistance to diminazeneaceturate was widespread in Trypanosoma congolense with percentages ranging from 67.85 (19/28) for Burkina Faso to 100% (9/9) for Ghana

Impact de l’usage des gants médicaux sur l’observance de l’hygiène des mains au cours des soins au Centre Hospitalier et Universitaire du Point G de Bamako

Objectif : Évaluer l'impact de l'usage des gants médicaux sur l'observance de l'hygiène des mains et promouvoir leur usage approprié. Matériel et Méthodes: Il s’agissait d’une étude interventionnelle avec une évaluation avant et après intervention. Sa mise en œuvre a été réalisée entre avril 2010 et octobre 2011 au Centre Hospitalier et Universitaire du Point G. Le recueil du consentement éclairé et les observations ont été effectués auprès du personnel soignant ayant un contact direct avec les patients avant et après intervention. Ces observations ont été discrètes mais ouvertes, menées auprès des soignants préalablement informés du but et du programme des activités. Résultats : Au total, 143 fiches de consentement éclairé ont été retournées sur une prévision de 274 fiches, soit 52,19%. Les observations ont donné un taux d’observance globale de 52,05% avant intervention contre 42,97% après intervention (p = 0,0017). Le taux global de port de gants était de 23,30% et 27,20% respectivement avant et après intervention (p = 0,12). Conclusion : Les résultats des deux évaluations avant et après intervention ont montré une amélioration du taux global de port des gants qui n’était pas significative mais sans impact sur l’observance de l’hygiène des mains

A major genetic locus in <i>Trypanosoma brucei</i> is a determinant of host pathology

The progression and variation of pathology during infections can be due to components from both host or pathogen, and/or the interaction between them. The influence of host genetic variation on disease pathology during infections with trypanosomes has been well studied in recent years, but the role of parasite genetic variation has not been extensively studied. We have shown that there is parasite strain-specific variation in the level of splenomegaly and hepatomegaly in infected mice and used a forward genetic approach to identify the parasite loci that determine this variation. This approach allowed us to dissect and identify the parasite loci that determine the complex phenotypes induced by infection. Using the available trypanosome genetic map, a major quantitative trait locus (QTL) was identified on T. brucei chromosome 3 (LOD = 7.2) that accounted for approximately two thirds of the variance observed in each of two correlated phenotypes, splenomegaly and hepatomegaly, in the infected mice (named &lt;i&gt;TbOrg1&lt;/i&gt;). In addition, a second locus was identified that contributed to splenomegaly, hepatomegaly and reticulocytosis (&lt;i&gt;TbOrg2&lt;/i&gt;). This is the first use of quantitative trait locus mapping in a diploid protozoan and shows that there are trypanosome genes that directly contribute to the progression of pathology during infections and, therefore, that parasite genetic variation can be a critical factor in disease outcome. The identification of parasite loci is a first step towards identifying the genes that are responsible for these important traits and shows the power of genetic analysis as a tool for dissecting complex quantitative phenotypic traits

In silico identification of a candidate synthetic peptide (Tsgf1(18-43)) to monitor human exposure to tsetse flies in West Africa

Background: The analysis of humoral responses directed against the saliva of blood-sucking arthropods was shown to provide epidemiological biomarkers of human exposure to vector-borne diseases. However, the use of whole saliva as antigen presents several limitations such as problems of mass production, reproducibility and specificity. The aim of this study was to design a specific biomarker of exposure to tsetse flies based on the in silico analysis of three Glossina salivary proteins (Ada, Ag5 and Tsgf1) previously shown to be specifically recognized by plasma from exposed individuals. Methodology/Principal Findings: Synthetic peptides were designed by combining several linear epitope prediction methods and Blast analysis. The most specific peptides were then tested by indirect ELISA on a bank of 160 plasma samples from tsetse infested areas and tsetse free areas. Anti-Tsgf1(18-43) specific IgG levels were low in all three control populations (from rural Africa, urban Africa and Europe) and were significantly higher (p < 0.0001) in the two populations exposed to tsetse flies (Guinean HAT foci, and South West Burkina Faso). A positive correlation was also found between Anti-Tsgf1(18-43) IgG levels and the risk of being infected by Trypanosoma brucei gambiense in the sleeping sickness foci of Guinea. Conclusion/Significance: The Tsgf1(18-43) peptide is a suitable and promising candidate to develop a standardize immunoassay allowing large scale monitoring of human exposure to tsetse flies in West Africa. This could provide a new surveillance indicator for tsetse control interventions by HAT control programs

Réactualisation des données sur la répartition des glossines au Mali

L'aire de répartition des glossines au Mali couvre environ 200 000 km2 au sud du parallèle 14 30' N et à l'ouest du méridien 4 30' O. Quatre espèces ont été signalées : deux riveraines (Glossina palpalis gambiensis et G. tachinoides) et deux de savane (G. morsitans submorsitans et G. longipalpis). G. morsitans submorsitans était répartie de manière plus ou moins continue le long des frontières avec la Côte d'Ivoire, la Guinée et le Sénégal jusqu'à la limite nord du parc national de la Boucle du Baoulé. A l'est de Bamako, la densité des populations était faible, apparemment discontinue dans les zones forestières. G. palpalis gambiensis était localisée le long de la rivière Bani, du fleuve Niger et de ses affluents, et des affluents du fleuve Sénégal (Baoulé, Bafing et Bagoé). G. tachinoides était répandue le long de la plupart des rivières et des grands cours d'eau de la partie sud-est du pays. Les prospections récentes n'ont pas revélé la présence de G. longipalpis au Mali. Après plusieurs années de sécheresse et/ou un défrichement intensif, une diminution relativement importante de l'aire de répartition des glossines dans le pays a été constatée

Variant antigen diversity in Trypanosoma vivax is not driven by recombination.

African trypanosomes (Trypanosoma) are vector-borne haemoparasites that survive in the vertebrate bloodstream through antigenic variation of their Variant Surface Glycoprotein (VSG). Recombination, or rather segmented gene conversion, is fundamental in Trypanosoma brucei for both VSG gene switching and for generating antigenic diversity during infections. Trypanosoma vivax is a related, livestock pathogen whose VSG lack structures that facilitate gene conversion in T. brucei and mechanisms underlying its antigenic diversity are poorly understood. Here we show that species-wide VSG repertoire is broadly conserved across diverse T. vivax clinical strains and has limited antigenic repertoire. We use variant antigen profiling, coalescent approaches and experimental infections to show that recombination plays little role in diversifying T. vivax VSG sequences. These results have immediate consequences for both the current mechanistic model of antigenic variation in African trypanosomes and species differences in virulence and transmission, requiring reconsideration of the wider epidemiology of animal African trypanosomiasis

Microsatellite analysis supports clonal propagation and reduced divergence of Trypanosoma vivax from asymptomatic to fatally infected livestock in South America compared to West Africa

Background: Mechanical transmission of the major livestock pathogen Trypanosoma vivax by other biting flies than\ud tsetse allows its spread from Africa to the New World. Genetic studies are restricted to a small number of isolates\ud and based on molecular markers that evolve too slowly to resolve the relationships between American and West\ud African populations and, thus, unable us to uncover the recent history of T. vivax in the New World.\ud Methods: T. vivax genetic diversity, population structure and the source of outbreaks was investigated through the\ud microsatellite multiloci (7 loci) genotype (MLGs) analysis in South America (47isolates from Brazil, Venezuela and\ud French Guiana) and West Africa (12 isolates from The Gambia, Burkina Faso, Ghana, Benin and Nigeria).\ud Relationships among MLGs were explored using phylogenetic, principal component and STRUCTURE analyses.\ud Results: Although closely phylogenetically related, for the first time, genetic differences were detected between\ud T. vivax isolates from South America (11 genotypes/47 isolates) and West Africa (12 genotypes/12 isolates) with no\ud MLGs in common. Diversity was far greater across West Africa than in South America, where genotypes from Brazil\ud (MLG1-6), Venezuela (MLG7-10) and French Guiana (MLG11) shared similar but not identical allele composition. No\ud MLG was exclusive to asymptomatic (endemic areas) or sick (outbreaks in non-endemic areas) animals, but only\ud MLGs1, 2 and 3 were responsible for severe haematological and neurological disorders.\ud Conclusions: Our results revealed closely related genotypes of T. vivax in Brazil and Venezuela, regardless of\ud endemicity and clinical conditions of the infected livestock. The MLGs analysis from T. vivax across SA and WA\ud support clonal propagation, and is consistent with the hypothesis that the SA populations examined here derived\ud from common ancestors recently introduced from West Africa. The molecular markers defined here are valuable to\ud assess the genetic diversity, to track the source and dispersion of outbreaks, and to explore the epidemiological\ud and pathological significance of T. vivax genotypes.This work was funded through projects within the PROAFRICA and PROSUL programs from the Brazilian agency CNPq. We are grateful to Professor Erney P. Camargo for the joint coordination of these projects and helpful commentaries on the manuscript. HAG was funded by a CDCH-UCV studentship from Venezuela; ACR is a postdoctoral fellow of PNPD-CAPES and CMFR is recipient of PhD scholarships from CNPq-PROTAX. The authors would like to acknowledge for clinical and epidemiological information, blood samples of T. vivax infected livestock and valuable help in the fieldwork several colleagues Garcia et al. Parasites & Vectors 2014, 7:210 Page 11 of 13\ud http://www.parasitesandvectors.com/content/7/1/210 from African countries, Venezuela and Brazil (Galiza GF, Da Silva A and Cadioli L\ud also for previous joint studies). We are grateful to The Wellcome Trust for making available sequences from the genome of T. vivax from Sanger Institute. We are deeply in debt to Wendy Gibson (Bristol University, UK) for helpful discussions and suggestions that much improved our manuscript