Apparent Densities of Stomoxys Species (Diptera, Muscidae) of Different Physiological Ages Caught with Vavoua Trap Differ With Landscape and Trapping Period

Stable flies (Stomoxys spp.) are common pests of livestock in the peri-urban rangelands of Vina Division of the Adamawa Plateau. No documented information is available on their diurnal dynamics in relation to physiological age and landscape. The main aim of this study was to determine the trap apparent density (ADT) of Stomoxys and associate it to their diurnal activity rhythm and landscape. Vavoua traps (n=12) were used for Stomoxys collection. Trapping was carried out for seven days i.e. three days consecutively in August and four days consecutively in October, 2016.Three traps were pitched in each of the three biotopes (river, cattle corral and gallery forest) of the four study sites (Galim, Mbidjoro, Velambai and Soukourwo). All female Stomoxys captured underwent ovarian dissection for the determination of their physiological ages (parous or nulliparous). A total of 218 Stomoxys were caught and identified into four species (S. niger niger, S. omega, S. calcitrans, and S.xanthomelas) with an overall ADT of 2.59 flies per trap per day and Stomoxys niger niger (1.13 s.n.n. per trap per day) recorded the highest ADT. Species richness was study site dependent.Higher catches of females 113 (51.83%) were made than that of their male 105 (48.17%) counterparts. Galim recorded the highest Stomoxys apparent density (4.90) as compared to other sites with a statistically significant difference (P<0.05). The proportion of parous 87 (59.30%) was higher than that of their nulliparous 46 (40.71%) counterparts. Parity differed with landscape and capture periods. S. n. niger was the most frequent in all biotopes and Galim recorded the highest ADT. The population of female flies was made up of adults (parous) with a bimodal diurnal activity rhythm whereas males had a unimodal activity rhythm.

Evaluation of the role of Guenons and Mangabeys in seed dispersal in Moukalaba-Doudou National Park, Gabon

In order to gain knowledge on the quantity of seed dispersed and the contribution of small diurnal primates in the ecosystem, a preliminary study&nbsp; on four species of monkeys was carried out in the northeastern part of the Moukalaba-Doudou National Park in Gabon. The aim was to identify the&nbsp; species of fruits which are dispersed and the animal biomass in two large groups of monkeys namely mangabeys (Cercocebus torquatus and&nbsp; Lophocebus albigena) and guenons (Cercopithecus cephus and Cercopithecus nictitans). Using the reconnaissance walking method, we followed old&nbsp; tracks and dung piles were collected after direct observation of the little monkeys and in the sleeping site. The dung piles were washed, and the&nbsp; seeds collected were identified. A total of 104 fecal samples from the four species of monkeys were collected. Seeds from 19 species of plants&nbsp; were found in the dung piles. The majority of the seeds found in droppings were seeds of Cissus dinklagei and Musanga cecropioides.&nbsp; Cercopithecus nictitans dispersed seeds of more plant species than the others. All the results obtained show that the monkeys disperse an average&nbsp; of 1,114 seeds per day. In this study guenons disperses more fruit than the mangabeys who have a more varied diet. These results suggest that&nbsp; monkeys of Moukalaba-Doudou disperse fewer seeds compared to monkeys in other sites in Africa. &nbsp; Afin d’avoir une connaissance sur la quantité de graine dispersée et la contribution des petits primates diurnes dans l’écosystème, une étude&nbsp; préliminaire sur quatre espèces de singes a été réalisée dans la partie nord-est du Parc National de Moukalaba-Doudou au Gabon. L’objectif était de&nbsp; connaître les espèces de fruits dispersées et la biomasse animale chez deux grands groupes de singes à savoir les mangabeys (Cercocebus&nbsp; torquatus et Lophocebus albigena) et les guenons (Cercopithecus cephus et Cercopithecus nictitans). En utilisant la méthode de la marche de&nbsp; reconnaissance, nous avons suivi d’anciennes pistes et les tas de fumier ont été ramassés après observation directe des petits singes et dans les&nbsp; dortoirs. Les crottes ont été lavées et les graines récoltées ont été identifiées. Un total de 104 échantillons fécaux des quatre espèces de singes a été&nbsp; collectés. Les graines de 19 espèces de plantes ont été trouvées dans les excréments. Cercopithecus nictitans a dispersé plus d’espèces de&nbsp; graines que les autres. La majorité des graines trouvées dans les déjections étaient des graines de Cissus dinklagei et Musanga cecropioides.&nbsp; L’ensemble des résultats obtenus montre que les singes dispersent en moyenne 1114 graines par jour. Dans cette étude les guenons dispersent plus&nbsp; de fruits que les mangabeys qui ont une alimentation plus variée. Ces résultats suggèrent que les singes de Moukalaba-Doudou dispersent&nbsp; peu de graines en comparaison aux singes d’autres sites en Afrique.&nbsp

Identification of novel orthonairoviruses from rodents and shrews in Gabon, Central Africa

In Africa, several emerging zoonotic viruses have been transmitted from small mammals such as rodents and shrews to humans. Although no clinical cases of small mammal-borne viral diseases have been reported in Central Africa, potential zoonotic viruses have been identified in rodents in the region. Therefore, we hypothesized that there may be unrecognized zoonotic viruses circulating in small mammals in Central Africa. Here, we investigated viruses that have been maintained among wild small mammals in Gabon to understand their potential risks to humans. We identified novel orthonairoviruses in 24.6 % of captured rodents and shrews from their kidney total RNA samples. Phylogenetic analysis revealed that the novel viruses, Lamusara virus (LMSV) and Lamgora virus, were closely related to Erve virus, which was previously identified in shrews of the genus Crocidura and has been suspected to cause neuropathogenic diseases in humans. Moreover, we show that the LMSV ovarian tumour domain protease, one of the virulence determination factors of orthonairoviruses, suppressed interferon signalling in human cells, suggesting the possible human pathogenicity of this virus. Taken together, our study demonstrates the presence of novel orthonairoviruses that may pose unrecognized risks of viral disease transmission in Gabon

Interactions hôte-parasite dans le modèle Biomphalaria pfeifferi-Schistosoma mansoni du Dhofar (Oman) : génétique des populations de l'hôte, traits d'histoire de vie et conséquences sur la transmission du parasite

This thesis has been conducted in the context of the reemergence of schistosomiasis caused by Schistosoma mansoni (flatworm trematode) in Dhofar (Oman). The work focuses on the host-parasite interactions and their implications on schistosome transmission. The first part is devoted to a spatiotemporal study of the population genetics iof Biomphalaria pfeifferi (freshwater gastropod snail). Nine microsatellite markers were used for characterization of 18 populations of B. pfeifferi. The results showed that intrapopulations genetic variability was very low. However, the population were highly differentiated. Temporal differentiation was also recorded in same populations. A second part concerns to the study of the life-history traits and host-parasite relationships. It was conducted using eight host-parasite combinations that differ either by the parasite population (human versus murine), by the waterbody category (natural versus man-made) or by the morph of the snail (pigmented versus albino). The following life-history traits were analyzed: growth, fecundity and survival of B. pfeifferi and rate of infection, prepatent period and cercarial production of S. mansoni. The results show that both the origin of S. mansoni and the pigmentation of B. pfeifferi play a major role in transmission of schistosomiasis in Dhofar. The results are discussed in terms of host-parasite compatibilityCette thèse a été réalisée dans le contexte de la réémergence de la schistosomose à Schistosoma mansoni (plathelminthe trématode) dans le Dhofar en Oman. Le travail est centré sur les interactions hôte-parasite et sur leurs conséquences sur la transmission du schistosome. Une première partie est consacrée à l'étude spatio-temporelle de la structure génétique des populations de Biomphalaria pfeifferi (mollusque gastéropode d'eau douce). Elle a été réalisée à l'aide de neuf marqueurs microsatellites sur 18 populations de mollusques. Les populations de B. pfeifferi étudiées sont caractérisées par une très faible variabilité génétique intra populationnelle. Par contre, elles sont fortement différenciées génétiquement. Une différenciation temporelle a également été enregistrée dans certaines populations. Une seconde partie est consacrée à l'étude des traits d'histoire de vie et des relations hôte-parasite. Elle a été réalisée à l'aide de huit combinaisons hôte-parasites qui diffèrent soit par la population de parasite (origine humaine ou origine murine), soit par la catégorie du site (naturel ou aménagé), soit par le morphe du mollusque (pigmenté ou albinos). Les traits d'histoire de vie suivants ont été analysés : croissance, fécondité et survie de B. pfeifferi et taux d'infestation, période prépatente et production cercarienne de S. mansoni. Les résultats montrent que la population de S. mansoni et le morphe de B. pfeifferi jouent un rôle majeur dans la transmission de la schistosomose dans le Dhofar. Les résultats sont discutés en termes de compatibilité hôte-parasite

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Interactions hôte-parasite dans le modèle Biomphalaria pfeifferi-Schistosoma mansoni du Dhofar (Oman) (génétique des populations de l hôte, traits d histoire de vie et conséquences sur la transmission du parasite)

Cette thèse a été réalisée dans le contexte de la réémergence de la schistosomose à Schistosoma mansoni (plathelminthe trématode) dans le Dhofar en Oman. Le travail est centré sur les interactions hôte-parasite et sur leurs conséquences sur la transmission du schistosome. Une première partie est consacrée à l étude spatio-temporelle de la structure génétique des populations de Biomphalaria pfeifferi (mollusque gastéropode d eau douce). Elle a été réalisée à l aide de neuf marqueurs microsatellites sur 18 populations de mollusques. Les populations de B. pfeifferi étudiées sont caractérisées par une très faible variabilité génétique intra populationnelle. Par contre, elles sont fortement différenciées génétiquement. Une différenciation temporelle a également été enregistrée dans certaines populations. Une seconde partie est consacrée à l étude des traits d histoire de vie et des relations hôte-parasite. Elle a été réalisée à l aide de huit combinaisons hôte-parasite qui diffèrent soit par la population de parasite (origine humaine ou origine murine), soit par la catégorie du site (naturel ou aménagé), soit par le morphe du mollusque (pigmenté ou albinos). Les traits d histoire de vie suivants ont été analysés : croissance, fécondité et survie de B. pfeifferi et taux d infestation, période prépatente et production cercarienne de S. mansoni. Les résultats montrent que la population de S. mansoni et le morphe de B. pfeifferi jouent un rôle majeur dans la transmission de la schistosomose dans le Dhofar. Les résultats sont discutés en termes de compatibilité hôte-parasite.PERPIGNAN-BU Sciences (661362101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Cercarial emergence pattern of Schistosoma haematobium from Libreville, Gabon

International audienceAlthough schistosomiasis has been a public health issue in Gabon for nearly a century, little is known about its current transmission dynamics. We analyzed the chronobiology of 137 cercarial emission profiles of Schistosoma haematobium from Libreville, the capital of Gabon, located in an open area for schistosomiasis. We found that 88% of the cercariae were shed between 11 a.m. and 3 p.m. and that the average pattern was of circadian type, with the average peak at 1 p.m., and representing 27% of the total number of cercariae of the day. The rhythms of emergence may be associated with environmental pressures on the parasite, especially those related to their definitive host

Host-parasite life-histories of the diurnal vs. nocturnal chronotypes of Schistosoma mansoni: adaptive significance

Objectives To optimise host-to-host transmission, digenean trematodes (parasites) synchronise their cercarial emission patterns with the aquatic activities of their vertebrate hosts. Schistosoma mansoni has two different circadian chronotypes: a diurnal shedding pattern with a mean peak occurring at 11:00 h, and a nocturnal shedding pattern with a mean peak occurring at 20:00 h. We analysed the life-history variations between these two chronotypes at the levels of the parasite and its hosts. Methods For each chronotype, we quantified three life-history traits related to the parasite (prepatent period, infection rate and cercarial production) and analysed the morphometry and the morphology of the parasite eggs; we also quantified three life-history traits related to the snail intermediate host (shell diameter, fecundity and survival rate) and one life-history trait related to the experimental definitive host (survival rate). A phylogeny based on the mitochondrial cytochrome-oxidase gene was made on samples of both chronotypes. Results Life-history analysis revealed significant variations between the two chronotypes. Life-history traits were optimal for both the parasite and the snail host for the diurnal chronotype compared to the nocturnal one. The new chronotype behaved like an allopatric population towards its snail host. Phylogenetic analysis supports the hypothesis of a lateral transfer of S. mansoni from humans to Rattus rattus. These results were interpreted in terms of an ongoing sympatric speciation. Conclusion The nocturnal chronotype of S. mansoni showed non-adapted life-history traits in its relation with the snail intermediate host Biomphalaria pfeifferi. The emergence of this new phenotype is probably linked to divergent natural selection

The phylogeny of the genus Indoplanorbis (Gastropoda, Planorbidae) from Africa and the French West Indies

International audienc

Introgressive hybridizations of Schistosoma haematobium by Schistosoma bovis at the origin of the first case report of schistosomiasis in Corsica (France, Europe)

International audienceThis study concerns the first urinary schistosomiasis case observed in Corsica (France, Europe) occurring in a 12-year-old German boy. The aim was to identify the relationship between this Schistosoma haematobium infection and other schistosomes of the Schistosoma group with terminal-spined ova. Morphological and molecular analyses were conducted on the ova. The results showed that the schistosome responsible for the emergence of schistosomiasis in Corsica was due to S. haematobium introgressed by genes from S. bovis