Diversity of modalities of Ebola virus transmission to human

La fièvre hémorragique Ébola est une zoonose qui se manifeste sous la forme de flambées épidémiques dont l’ampleur et la fréquence n’ont cessé de croître au cours des dernières années. Malgré l’introduction de vaccins, la lutte contre les épidémies se heurte à leur imprévisibilité, elle-même liée aux nombreuses interrogations sur les modes de contamination de l’Homme, qu’elle soit d’origine zoonotique ou humaine. En effet, les mécanismes de la transmission interhumaine du virus semblent beaucoup plus complexes et variés que le seul contact avec les fluides biologiques sanglants des patients. Le rôle de la faune animale lors de l’apparition des flambées épidémiques reste énigmatique en raison des incertitudes sur l’identité du réservoir et sur le nombre des espèces animales sensibles. Enfin, l’implication des animaux domestiques dans la dissémination du virus en contexte épidémique a probablement été largement sous-évaluée. L’élucidation de tous ces points constitue un enjeu scientifique et sanitaire majeur si l’on veut pouvoir combattre efficacement le virus Ebola et envisager la disparition des épidémies.Ebola haemorrhagic fever is a zoonotic disease that appears in the form of epidemic outbreaks whose magnitude and frequency have steadily increased in recent years. Despite the introduction of vaccines to treat patients, the fight against outbreaks comes up because of their unpredictability which is itself linked to numerous questions about man’s modes of contamination, whether of zoonotic or human origin.. In fact, human-to-human transmissions of the virus seem to be much more diversified than the only contact with the bloody biological fluids of the patients. The role of animal fauna during outbreaks remains enigmatic because of uncertainties about the identity of the reservoir and the number of susceptible animal species. Finally, the involvement of domestic animals in the spread of the virus in an epidemic context has probably been largely undervalued. The elucidation of all these points is a major scientific and health issue if we want to effectively fight the Ebola virus and consider the disappearance of epidemics

Bat flies (Diptera: Nycteribiidae and Streblidae) infesting cave-dwelling bats in Gabon: Diversity, dynamics and potential role in Polychromophilus melanipherus transmission

Background Evidence of haemosporidian infections in bats and bat flies has motivated a growing interest in characterizing their transmission cycles. In Gabon (Central Africa), many caves house massive colonies of bats that are known hosts of Polychromophilus Dionisi parasites, presumably transmitted by blood-sucking bat flies. However, the role of bat flies in bat malaria transmission remains under-documented. Methods An entomological survey was carried out in four caves in Gabon to investigate bat fly diversity, infestation rates and host preferences and to determine their role in Polychromophilus parasite transmission. Bat flies were sampled for 2–4 consecutive nights each month from February to April 2011 (Faucon and Zadie caves) and from May 2012 to April 2013 (Kessipoughou and Djibilong caves). Bat flies isolated from the fur of each captured bat were morphologically identified and screened for infection by haemosporidian parasites using primers targeting the mitochondrial cytochrome b gene. Results Among the 1,154 bats captured and identified as Miniopterus inflatus Thomas (n = 354), Hipposideros caffer Sundevall complex (n = 285), Hipposideros gigas Wagner (n = 317), Rousettus aegyptiacus Geoffroy (n = 157, and Coleura afra Peters (n = 41), 439 (38.0 %) were infested by bat flies. The 1,063 bat flies recovered from bats belonged to five taxa: Nycteribia schmidlii scotti Falcoz, Eucampsipoda africana Theodor, Penicillidia fulvida Bigot, Brachytarsina allaudi Falcoz and Raymondia huberi Frauenfeld group. The mean infestation rate varied significantly according to the bat species (ANOVA, F (4,75) = 13.15, P < 0.001) and a strong association effect between bat fly species and host bat species was observed. Polychromophilus melanipherus Dionisi was mainly detected in N. s. scotti and P. fulvida and less frequently in E. africana, R. huberi group and B. allaudi bat flies. These results suggest that N. s. scotti and P. fulvida could potentially be involved in P. melanipherus transmission among cave-dwelling bats. Sequence analysis revealed eight haplotypes of P. melanipherus. Conclusions This work represents the first documented record of the cave-dwelling bat fly fauna in Gabon and significantly contributes to our understanding of bat fly host-feeding behavior and their respective roles in Polychromophilus transmission. (Résumé d'auteur

Identification and characterization of RNA viruses potentially pathogenic to humans hosted by the populations of bats in Central Africa

Le nombre de virus détectés chez les chauves-souris est en augmentation, la plupart étant des virus à ARN. L'identification chez différentes espèces de chauves-souris, de virus ayant été responsables d'épidémies voire de pandémies chez l'homme (coronavirus agent du SRAS, virus Nipah et Hendra, filovirus Ebola et Marburg) a fait prendre conscience du risque que peuvent présenter ces animaux pour la santé humaine, ainsi que des possibilités réelles d'émergence de nouvelles pathologies dans les années futures. Ce travail avait donc pour objectifs: (i) d'identifier et caractériser les virus circulant au sein des populations de chauves-souris d'Afrique Centrale et (ii) d'explorer et d'identifier des déterminants bioécologiques, qui pourraient expliquer la richesse virale observée chez certaines espèces de chauves-souris rencontrées en Afrique tropicale forestière. A partir d'un total de 3472 individus testés, représentant 16 espèces provenant du Gabon, de la République du Congo et de la République Centrafricaine, nous avons confirmé la présence du virus Marburg chez les roussettes d'Egypte (Rousettus aegyptiacus) au Gabon, et mis en évidence des séquences virales de paramyxovirus très proches de virus zoonotiques émergents (les virus Nipah et Hendra) et réémergents (virus des oreillons) chez des chauves-souris frugivores. Des séquences de nouveaux coronavirus, flavivirus et paramyxovirus ont été également identifiées. Par ailleurs, la fragmentation de l'aire de distribution et le type de gîte ont été identifiés comme des déterminants de la richesse virale chez 15 espèces de chauves-souris d'Afrique Centrale. Les chauves-souris en Afrique Centrale seraient donc des réservoirs de virus apparentés à des virus pathogènes pour l'homme. Ces animaux pourraient donc être à l'origine de l'émergence des encéphalites à hénipavirus en Afrique et de la réémergence de certaines maladies humaines comme les oreillons, la rougeole. Des recherches futures s'orienteront vers la poursuite de la caracterisation génétique des virus détectés chez les chauves-souris d'Afrique Centrale et la détermination du risque zoonotique associé à ces virus. Des études écologiques seront également réalisées pour identifier les facteurs de risque d'émeregence des virus de chauves-souris potentiellement pathogènes pour l'homme.The number of viruses détected in bats is growing, the most common are RNA viruses. The identification in different bat species of viruses that cause major epidemics or pandemics in human such as SARS coronavirus, Nipah and Henda viruses, the filoviruses Ebola and Marburg has raised awareness of potential risk that these animals may present to human health, as well as real possibilities of development of new diseases in future years. This work had two objectives: (i) to identify and characterize the viruses circulating in populations of bats in Central Africa and (ii) to explore and identify bioecological factors that could explain the viral richness observed in some bats species seen in tropical Africa forest. From 3472 individuals tested accounting for 16 species from Gabon, Congo and the Central African Republic, we established the presence of Marburg virus in Egyptian fruit bats (Rousettus aegyptiacus) in Gabon and identified viral sequences of paramyxoviruses close related to emerging and re-emerging zoonotic paramyxoviruses (Nipah virus, Hendra viruses and mumps virus) in fruit bats. Sequences of novel coronaviruses, paramyxoviruses and flaviviruses have also beenidentified. Moreover, the fragmentation of the range and roost type have been identified as determinants of viral richness in 15 bats species of Central Africa. Bats in Central Africa thus would be reservoirs of viruses related to viruses pathogenic for humans. These animals would lead to the emergence of encephalitis Henipavirus in Africa and the reemergence of certain human diseases such as mumps, measles. Further research will be conducted to continue the genetic characterization of viruses detected from bats in Central Africa and to determine the zoonotic risk associated with these viruses. Ecological studies will also be performed to identify the risk factors for the emergence of bats viruses potentially pathogenic for humans

Diversité des modalités de transmission du virus Ébola à l’homme

Diversity of modalities of Ebola virus transmission to human Ebola haemorrhagic fever is a zoonotic disease that appears in the form of epidemic outbreaks whose magnitude and frequency have steadily increased in recent years. Despite the introduction of vaccines to treat patients, the fight against outbreaks comes up because of their unpredictability which is itself linked to numerous questions about man’s modes of contamination, whether of zoonotic or human origin.. In fact, human-to-human transmissions of the virus seem to be much more diversified than the only contact with the bloody biological fluids of the patients. The role of animal fauna during outbreaks remains enigmatic because of uncertainties about the identity of the reservoir and the number of susceptible animal species. Finally, the involvement of domestic animals in the spread of the virus in an epidemic context has probably been largely undervalued. The elucidation of all these points is a major scientific and health issue if we want to effectively fight the Ebola virus and consider the disappearance of epidemics.La fièvre hémorragique Ébola est une zoonose qui se manifeste sous la forme de flambées épidémiques dont l’ampleur et la fréquence n’ont cessé de croître au cours des dernières années. Malgré l’introduction de vaccins, la lutte contre les épidémies se heurte à leur imprévisibilité, elle-même liée aux nombreuses interrogations sur les modes de contamination de l’Homme, qu’elle soit d’origine zoonotique ou humaine. En effet, les mécanismes de la transmission interhumaine du virus semblent beaucoup plus complexes et variés que le seul contact avec les fluides biologiques sanglants des patients. Le rôle de la faune animale lors de l’apparition des flambées épidémiques reste énigmatique en raison des incertitudes sur l’identité du réservoir et sur le nombre des espèces animales sensibles. Enfin, l’implication des animaux domestiques dans la dissémination du virus en contexte épidémique a probablement été largement sous-évaluée. L’élucidation de tous ces points constitue un enjeu scientifique et sanitaire majeur si l’on veut pouvoir combattre efficacement le virus Ebola et envisager la disparition des épidémies.Leroy Éric Maurice, Maganga Gaël Darren. Diversité des modalités de transmission du virus Ébola à l’homme. In: Bulletin de l'Académie Vétérinaire de France tome 171 n°2, 2018. pp. 128-136

Surveillance des agents pathogènes d’origine virale, bactérienne et parasitaire chez des bovins importés au Gabon pour la consommation. Une étude en abattoir

Maganga Gaël Darren, Ndong Mebaley Telstar Ghestin, Goussingou Mackayat Jeanaïne, Moubamba Mbina Dieudonné. Surveillance des agents pathogènes d’origine virale, bactérienne et parasitaire chez des bovins importés au Gabon pour la consommation. Une étude en abattoir. In: Bulletin de l'Académie Vétérinaire de France tome 174, 2021. pp. 286-293

An experimental game to assess hunter’s participation in zoonotic diseases surveillance

Abstract Background Strengthening the surveillance of zoonotic diseases emergence in the wild meat value chains is a critical component of the prevention of future health crises. Community hunters could act as first-line observers in zoonotic pathogens surveillance systems in wildlife, by reporting early signs of the possible presence of a disease in the game animals they observe and manipulate on a regular basis. Methods An experimental game was developed and implemented in a forested area of Gabon, in central Africa. Our objective was to improve our understanding of community hunters' decision-making when finding signs of zoonotic diseases in game animals: would they report or dissimulate these findings to a health agency? 88 hunters, divided into 9 groups of 5 to 13 participants, participated in the game, which was run over 21 rounds. In each round the players participated in a simulated hunting trip during which they had a chance of capturing a wild animal displaying clinical signs of a zoonotic disease. When signs were visible, players had to decide whether to sell/consume the animal or to report it. The last option implied a lowered revenue from the hunt but an increased probability of early detection of zoonotic diseases with benefits for the entire group of hunters. Results The results showed that false alerts—i.e. a suspect case not caused by a zoonotic disease—led to a decrease in the number of reports in the next round (Odds Ratio [OR]: 0.46, 95% Confidence Interval [CI]: 0.36–0.8, p < 0.01). Hunters who had an agricultural activity in addition to hunting reported suspect cases more often than others (OR: 2.05, 95% CI: 1.09–3.88, p < 0.03). The number of suspect case reports increased with the rank of the game round (Incremental OR: 1.11, CI: 1.06–1.17, p < 0.01) suggesting an increase in participants’ inclination to report throughout the game. Conclusion Using experimental games presents an added value for improving the understanding of people’s decisions to participate in health surveillance systems

Molecular identification of trypanosome species in trypanotolerant cattle from the south of Gabon

The aim of this study was to provide information on trypanosome species infecting trypanotolerant cattle from southern Gabon. The study was conducted on 224 trypanotolerant cattle from three regions located in southern Gabon, using ITS1 primer-based PCR. Seventy-two (32%) N’dama cattle were found polymerase chain reaction (PCR) positive with trypanosomes. The overall prevalence of trypanosomosis was 57% (63/110), 4% (4/100), and 36% (5/14) in the Gala section of the Nyanga ranch, the Miyama ranch, and Ossiele, respectively. Trypanosoma congolense and Trypanosoma vivax were identified. In Gala section and Ossiele, T. congolense and T. vivax were found. In the Miyama ranch, only T. vivax was identified. Mixed infections were also found. The forest (9%) and savannah (63%) subgroups of T. congolense were identified. The presence of the two subgroups was detected in 16 out of 56 cattle (29%). T. congolense and T. vivax would appear to be the main agents responsible for bovine trypanosomosis in southern Gabon. Although trypanotolerant, N’dama cattle may serve as a reservoir, and this should be further studied. On the other hand, these trypanotolerant cattle can be reared in such tsetse infested areas, which gives them an advantage compared to other trypanosensitive breeds, and this shows that they represent a key factor in biodiversity which has to be promoted

Molecular identification of trypanosome species in trypanotolerant cattle from the south of Gabon

The aim of this study was to provide information on trypanosome species infecting trypanotolerant cattle from southern Gabon. The study was conducted on 224 trypanotolerant cattle from three regions located in southern Gabon, using ITS1 primer-based PCR. Seventy-two (32%) N’dama cattle were found polymerase chain reaction (PCR) positive with trypanosomes. The overall prevalence of trypanosomosis was 57% (63/110), 4% (4/100), and 36% (5/14) in the Gala section of the Nyanga ranch, the Miyama ranch, and Ossiele, respectively. Trypanosoma congolense and Trypanosoma vivax were identified. In Gala section and Ossiele, T. congolense and T. vivax were found. In the Miyama ranch, only T. vivax was identified. Mixed infections were also found. The forest (9%) and savannah (63%) subgroups of T. congolense were identified. The presence of the two subgroups was detected in 16 out of 56 cattle (29%). T. congolense and T. vivax would appear to be the main agents responsible for bovine trypanosomosis in southern Gabon. Although trypanotolerant, N’dama cattle may serve as a reservoir, and this should be further studied. On the other hand, these trypanotolerant cattle can be reared in such tsetse infested areas, which gives them an advantage compared to other trypanosensitive breeds, and this shows that they represent a key factor in biodiversity which has to be promoted