Search

Urbanization processes are taking place at a very high rate, especially in Africa. At the same time, a number of small mammal species, be they native or invasive, take advantage of human‐induced habitat modifications. They represent commensal communities of organisms that cause a number of inconveniences to humans, including potential reservoirs of zoonotic diseases. We studied via live trapping and habitat characterization such commensal small mammal communities in small villages to large cities of Senegal, to try to understand how the species share this particular space. Seven major species were recorded, with exotic invasive house mice (Mus musculus) and black rats (Rattus rattus) dominating in numbers. The shrew Crocidura olivieri appeared as the main and more widespread native species, while native rodent species (Mastomys natalensis, M. erythroleucus, Arvicanthis niloticus and Praomys daltoni) were less abundant and/or more localized. Habitat preferences, compared between species in terms of room types and characteristics, showed differences among house mice, black rats and M. natalensis especially. Niche (habitat component) breadth and overlap were measured. Among invasive species, the house mouse showed a larger niche breadth than the black rat, and overall, all species displayed high overlap values. Co‐occurrence patterns were studied at the global and local scales. The latter show cases of aggregation (between the black rat and native species, for instance) and of segregation (as between the house mouse and the black rat in Tambacounda, or between the black rat and M. natalensis in Kédougou). While updating information on commensal small mammal distribution in Senegal, a country submitted to a dynamic process of invasion by the black rat and the house mouse, we bring original information on how species occupy and share the commensal space, and make predictions on the evolution of these communities in a period of ever‐accelerating global changes. [ABSTRACT FROM AUTHOR]

The article focuses on the emergence of Coxiella burnetii, the causative agent of Q fever, in rodents in northern Senegal. Topics include the detection of a new C. burnetii genotype in rodents, the potential ongoing epizootic outbreak, and the need for epidemiologic surveillance in humans in Senegal to monitor C. burnetii infection.

Zoonotic pathogens are responsible for most infectious diseases in humans, with rodents being important reservoir hosts for many of these microorganisms. Rodents, thus, pose a significant threat to public health. Previous studies in Senegal have shown that rodents harbour a diversity of microorganisms, including human pathogens. Our study aimed to monitor the prevalence of infectious agents in outdoor rodents, which can be the cause of epidemics. We screened 125 rodents (both native and expanding) from the Ferlo region, around Widou Thiengoly, for different microorganisms. Analysis, performed on rodent spleens, detected bacteria from the Anaplasmataceae family (20%), Borrelia spp. (10%), Bartonella spp. (24%) and Piroplasmida (2.4%). Prevalences were similar between native and the expanding (Gerbillus nigeriae) species, which has recently colonised the region. We identified Borrelia crocidurae, the agent responsible for tick-borne relapsing fever, which is endemic in Senegal. We also identified two other not-yet-described bacteria of the genera Bartonella and Ehrlichia that were previously reported in Senegalese rodents. Additionally, we found a potential new species, provisionally referred to here as Candidatus Anaplasma ferloense. This study highlights the diversity of infectious agents circulating in rodent populations and the importance of describing potential new species and evaluating their pathogenicity and zoonotic potential. [ABSTRACT FROM AUTHOR]

Copyright of Parasite (1252607X) is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biological invasions provide unique opportunities for studying life history trait changes over contemporary time scales. As spatial spread may be related to changes in parasite communities, several hypotheses (such as the evolution of increased competitive ability (EICA) or EICA-refined hypotheses) suggest immune changes in invasive species along invasion gradients. Although native hosts may be subject to similar changes in parasite selection pressures, their immune responses have been rarely investigated in invasion contexts. In this study, we evaluated immune variations for invasive house mice Mus musculus domesticus, invasive black rats Rattus rattus and native rodents Mastomys erythroleucus and Mastomys natalensis along well-characterised invasion gradients in Senegal. We focused on antibody-mediated (natural antibodies and complement) and inflammatory (haptoglobin) responses. One invasion route was considered for each invasive species, and environmental conditions were recorded. Natural-antibody mediated responses increased between sites of long-established invasion and recently invaded sites only in house mice. Both invasive species exhibited higher inflammatory responses at the invasion front than in sites of long-established invasion. The immune responses of native species did not change with the presence of invasive species. These patterns of immune variations do not support the EICA and EICA refined hypotheses, and they rather suggest a higher risk of exposure to parasites on the invasion front. Altogether, these results provide a first basis to further assess the role of immune changes in invasion success. [ABSTRACT FROM AUTHOR]

Invasive rodents have been responsible for the diffusion worldwide of many zoonotic agents, thus representing major threats for public health. Cities are important hubs for people and goods exchange and are thus expected to play a pivotal role in invasive commensal rodent dissemination. Yet, data about urban rodents' ecology, especially invasive vs. native species interactions, are dramatically scarce. Here, we provide results of an extensive survey of urban rodents conducted in Niamey, Niger, depicting the early stages of rodent bioinvasions within a city. We explore the species-specific spatial distributions throughout the city using contrasted approaches, namely field sampling, co-occurrence analysis, occupancy modelling and indicator geostatistics. We show that (i) two species (i.e. rural-like vs. truly commensal) assemblages can be identified, and that (ii) within commensal rodents, invasive (Rattus rattus and Mus musculus) and native (Mastomys natalensis) species are spatially segregated. Moreover, several pieces of arguments tend to suggest that these exclusive distributions reflect an ongoing native-to-invasive species turn over. The underlying processes as well as the possible consequences for humans are discussed. [ABSTRACT FROM AUTHOR]

The small-mammal community of a typical Sudanian savannah area of south-eastern Senegal was studied by way of intensive sampling at the beginning (July) and at the end (November) of the rainy season. A total of 5931 trapnights and 200 pitfallnights yielded 767 small mammals, including 757 rodents of 12 species, as well as a few shrews and hedgehogs. Accumulation curve indicated that the rodent community was well sampled. Murine rodents were far more numerous than gerbilline rodents, and among them, Mastomys erythroleucus was the dominant species, being caught in high numbers in all habitats. Arvicanthis niloticus and Praomys daltoni were also abundant, followed by Mastomys natalensis and Gerbilliscus guineae. Abundances were high at the beginning of the rainy season when reproductive activity was low in all species. At the end of the rainy season, murine rodents were actively involved in reproduction, while gerbilline rodents were at their lowest density. Significant changes in relative abundance among habitats (including human dwellings) were observed between periods in some species, suggesting seasonal trends in habitat preferences. This may help species coexistence in this species-rich rodent community, in an area likely to be submitted to significant habitat alterations in the years to come. [ABSTRACT FROM AUTHOR]

Describing patterns and testing hypotheses on processes driving biological invasions represent major issues in ecology. Addressing these questions requires building adequate data sets, i.e., covering areas and spanning periods adapted to the invasion processes studied. Rodents include major invasive species, among which the black rat Rattus rattus and the domestic mouse Mus musculus have nearly colonized the entire world, from their native Asian range. To do so, they have benefitted from their ability to cope with human‐modified environments and to live in the immediate vicinity of Man, who served as a vector of their dispersal between regions and continents. In Senegal, both R. rattus and M. musculus, initially introduced by early West European colonizers some centuries ago, are currently expanding thanks to road traffic and infrastructure development and rampant urbanization that concerns even remote regions of the country. As part of projects aimed at studying (1) the role of invasive black rat populations in the emergence of zoonotic diseases in southeastern Senegal, and (2) the evolutionary consequences of parasites in R. rattus and M. musculus invasions in Senegal, we conducted a series of field campaigns throughout the southern half of the country, between May 2012 and September 2015. The objectives were to catch commensal small mammals using standard trapping procedures, identify them using morphological or molecular tools, and take samples from them upon autopsy, to look for zoonotic parasites and pathogens. Along with data on individual specimens, information on microhabitats was gathered at each trap position. This resulted in the constitution of a data set of more than 13,000 trapnights, which allowed the capture of more than 3,100 small mammals, all characterized by a series of associated biological, geographical, and environmental data. The small mammals concerned are mainly rodents (10 species), shrews, and hedgehogs. The two invasive rodent species were the most numerous, exceeding in numbers all the other species pooled. This data set makes it possible to study coarse to fine‐scaled distribution of species of this commensal community in southern Senegal, as well as the possible determinants of this distribution in terms of habitat preferences and/or interspecific interactions. This data set can be freely used for non‐commercial purposes and is licensed under a Creative Commons Attribution 4.0 International License. [ABSTRACT FROM AUTHOR]

Abstract: Rodent diagnosis has long remained obscured by the co-existence of cryptic species in many lineages. However, alternative and accessible methods, such as cytotaxonomy and DNA-based methods, are now available that allow biologists to accurately monitor biodiversity through the production of well documented lists of unambiguously species-specific identifications. As a continuation of our previous surveys of West African rodents, we here present the first rodent inventory of rodents from Northern Cameroon (as well as one locality in Western Chad) that fully relies on karyotypic and/or sequencing data. Doing so, we assess the presence of 18 species in this poorly documented region. Among them, we found several African spiny mice that could be referred as to A. johannis, a poorly documented species. Moreover, several Arvicanthis individuals could be aggregated with previously studied but still enigmatic specimens of ANI-2 and ANI-4 sensu, thus suggesting that they may all belong to one single species, namely A. rufinus. In addition, one specimen was shown to belong to a new biological species (Praomys sp.) that will deserve further taxonomic investigations. Finally, several Taterillus specimens were found with 2n =28–30 chromosomes and a XX/XY1Y2 sex chromosome system. On the basis of these new results as well as a reinterpretation of previously published data, we propose to refer these individuals as to the poorly documented Taterillus lacustris. Altogether, our data suggest that Northern Cameroon is a “phylogeographical node” for several rodent lineages which may be at least partly explained by the past changes within the Lake Chad basin. Keeping this in mind, there is little doubt that biodiversity will undergo important modifications in the coming decades, following the increasing aridity and the drastic reduction of Lake Chad. [Copyright &y& Elsevier]

Graphical abstract Highlights • The modified agglutination test (MAT) should not be used for Toxoplasma gondii detection in wild Mus musculus domesticus. • Prevalence of T. gondii infection varies significantly between species. • Both transcontinental and African lineages of T. gondii are found in Senegal. • The African T. gondii lineage Africa 1 was only found in native African small mammals. Abstract Commensal rodent species are key reservoirs for Toxoplasma gondii in the domestic environment. In rodents, different T. gondii strains show variable patterns of virulence according to host species. Toxoplasma gondii strains causing non-lethal chronic infections in local hosts will be more likely to persist in a given environment, but few studies have addressed the possible role of these interactions in shaping the T. gondii population structure. In addition, the absence of validated techniques for upstream detection of T. gondii chronic infection in wild rodents hinders exploration of this issue under natural conditions. In this study, we took advantage of an extensive survey of commensal small mammals in three coastal localities of Senegal, with a species assemblage constituted of both native African species and invasive species. We tested 828 individuals for T. gondii chronic infection using the modified agglutination test for antibody detection in serum samples and a quantitative PCR assay for detection of T. gondii DNA in brain samples. The infecting T. gondii strains were genotyped whenever possible by the analysis of 15 microsatellite markers. We found (i) a very poor concordance between molecular detection and serology in the invasive house mouse, (ii) significantly different levels of prevalence by species and (iii) the autochthonous T. gondii Africa 1 lineage strains, which are lethal for laboratory mice, only in the native African species of commensal small mammals. Overall, this study highlights the need to reconsider the use of MAT serology in natural populations of house mice and provides the first known data about T. gondii genetic diversity in invasive and native species of small mammals from Africa. In light of these results, we discuss the role of invasive and native species, with their variable adaptations to different T. gondii strains, in shaping the spatial structure of T. gondii genetic diversity in Africa. [ABSTRACT FROM AUTHOR]