Mastitis is a multifactorial infection of the udder potentially caused by many pathogens of varying severity and prevalence and it is one of the most common diseases on dairy farms. Limited information exists about the ecological interactions among pathogens in mastitis infections. This study aims (1) to identify the potential sources of the mastitis-causing pathogens at the farm level, (2) to analyse the statistical associations and dynamics of these pathogens over time in the milk microbiota, and (3) to assess their impact on somatic cell count (SCC) fluctuation. To address these objectives, two 4-month longitudinal studies were conducted on cows of six dairy farms in the Auvergne region of France. Milk and faeces were collected from a total of 33 cows, along with environmental samples (bedding and milk filter). A commercial qPCR kit (PathoProof™) was used to quantify 15 mastitis-causing pathogens in these samples. The data were then processed using Principal Component Analysis, the Ward clustering method and discrete-time Markov chain models. Clustering analyses of quarter milk samples revealed distinct profiles of pathogen distribution associated with specific SCC and cow recovery dynamics. Notably, profiles involving Corynebacterium bovis, though considered a minor pathogen, were associated with persistent infections and variable SCC levels. We also described co-infections between C. bovis and Streptococcus uberis. Non-aureus staphylococci (NAS) were associated with a wide range of effects on udder health, as they constitute a diverse bacterial group, and detection of this group in the udder might generally not be sufficient to confirm a mastitis diagnosis. We highlight the importance of considering multi-pathogen associations and longitudinal dynamics in udder health management.

AbstractBackgroundLeptospirosis is a zoonotic disease. It is particularly prevalent in tropical countries and has major consequences for human and animal health. In Benin, the disease's epidemiology remains poorly understood, especially in livestock, for which data are lacking.ObjectivesTo characterise Leptospira seroprevalence and locally circulating serogroups in livestock from Cotonou and to estimate the prevalence of Leptospira renal carriage in cattle.MethodsWe conducted a cross‐sectional study in February 2020 during which livestock were sampled at an abattoir and in an impoverished city district. We analysed blood samples from 279 livestock animals (i.e. cattle, sheep, goats and pigs) using the microscopic agglutination test. Additionally, samples of renal tissue from 100 cattle underwent 16s rRNA (rrs) real‐time PCR analysis.ResultsFor the 131 cattle, 85 sheep, and 50 goats tested, seroprevalence was 18% (95% confidence interval [CI] [12%, 26%]), 9% (95% CI [4%, 17%] and 2% (95% CI [0%, 9%]), respectively, and most of the seropositive animals were associated with 1:100 titres. All 13 pigs were seronegative. Leptospira DNA was found in the renal tissue of 10% (95% CI [5%, 18%]) of the cattle tested (n = 100). Leptospira borgpetersenii was the main species present (n = 7), but Leptospira interrogans (n = 2) and Leptospira kirschneri (n = 1) were also detected. Various serogroups (Canicola, Grippotyphosa, Sejroe, Icterohaemorrhagiae, Pomona, Pyrogenes, Australis and Autumnalis) were detected using microscopic agglutination test without a clear predominance of any of them.ConclusionsThese results suggest that abattoir workers and people living in close contact with livestock in poor urban areas are exposed to the risk of Leptospira infection.

BACKGROUND:Leptospirosis is a widespread zoonotic disease caused by pathogenic Leptospira and is responsible for significant economic porcine livestock losses. Knowledge of Leptospira serogroups and their distributions is important for evaluation of the relevance of leptospirosis management measures, including use of the prophylactic vaccine that was recently made available in France. A retrospective study was conducted to determine the relationships between different circulating Leptospira serogroups. Pigs from across France presenting clinical signs suggestive of leptospirosis were tested with the microagglutination test (MAT) between 2011 and 2017. We used weighted averages to determine serogroup distributions according to MAT results and considering cross-reactions.RESULTS:A total of 19,395 pig sera, mostly from Brittany, were tested, and 22.7% were found to be positive for at least one Leptospira serogroup. Analysis of the 4,346 seropositive results for which the putative infective serogroup could be defined, revealed that two out of ten serogroups were much more frequent than the others: Australis (48.5%) and Icterohaemorrhagiae (38.2%). Other serogroups, including Autumnalis, Panama, Ballum, Tarassovi, Sejroe, Grippotyphosa, Bataviae, and Pomona, were less common.CONCLUSIONS:Although diagnostic laboratory data cannot be extrapolated to infer the distribution of Leptospira serogroups at the nationwide scale in France, the analysis of such data can provide an overview of the relationship between circulating Leptospira serogroups in space and time. During the last decade, protection against the serogroups Australis and Icterohaemorrhagiae would have prevented most of the clinical porcine leptospirosis cases in the large number of farms that we studied. In the future, epidemiological information related to circulating Leptospira serogroups should be extracted from data with a standardized approach for use in nationwide or international surveillance and prophylactic strategy support.

Given the difficulty of measuring pathogen transmission in wildlife, epidemiological studies frequently rely on cross-sectional seroprevalence. However, seropositivity indicates only exposure to a pathogen at an unknown time. By allowing to obtain repeated test results from individuals sampled multiple times over an extended period, longitudinal data help reduce this uncertainty. We used capture-mark-recapture data on bank vole (Myodes glareolus) individuals collected at four sites over ten years in northeastern France to investigate the impact of environmental variables on seroprevalence and incidence of Puumala orthohantavirus (PUUV). PUUV causes a chronic infection without apparent symptoms, that may however impair survival of its rodent host in the wild. Viral transmission between rodents may occur through direct contact or via the environment. Principal component analysis was used to deal with multicollinearity among environmental variables. Incidence and seroprevalence were investigated with either generalized estimating equations or Poisson regression models depending on the number of observations for each season. In spring, only the factor site was found to be significant for seroprevalence, while a principal component including meteorological conditions of the previous winter and the normalized difference vegetation index (NDVI) of both the previous winter and spring had a significant effect on incidence. In autumn, only the factor site was significant for incidence, while two principal components, including either the meteorological conditions of the autumn and previous spring or NDVI of the autumn significantly affected seroprevalence. We discuss these results in light of the particular demography of small mammals. We encourage other researchers to investigate the relationships between demographic parameters of wild host populations and the environment, by using both incidence and seroprevalence.

Mammarenaviruses have been a growing concern for public health in Africa since the 1970s when Lassa virus cases in humans were first described in west Africa. In southern Africa, a single outbreak of Lujo virus was reported to date in South Africa in 2008 with a case fatality rate of 80%. The natural reservoir of Lassa virus is Mastomys natalensis while for the Lujo virus the natural host has yet to be identified. Mopeia virus was described for the first time in M. natalensis in the central Mozambique in 1977 but few studies have been conducted in the region. In this study, rodents were trapped between March and November 2019in villages, croplands fields and mopane woodland forest. The aim was to assess the potential circulation and to evaluate the genetic diversity of mammarenaviruses in M. natalensis trapped in the Limpopo National Park and its buffer zone in Massingir district, Mozambique. A total of 534 M. natalensis were screened by RT-PCR and the overall proportion of positive individuals was 16.9%. No significant differences were detected between the sampled habitats (χ2 = 0.018; DF = 1; p = 0.893). The Mopeia virus (bootstrap value 91%) was the Mammarenavirus circulating in the study area sites, forming a specific sub-clade with eight different sub-clusters. We concluded that Mopeia virus circulates in all habitats investigated and it forms a different sub-clade to the one reported in central Mozambique in 1977.

Background: Leptospirosis is a widespread zoonotic disease caused by pathogenic Leptospira and is responsible for significant economic losses in porcine livestock. Knowledge of Leptospira serogroups and their distributions is important for evaluating the relevance of leptospirosis management measures, including the use of the prophylactic vaccine recently made available in France.A retrospective study was conducted to determine the distribution of Leptospira serogroups. Pigs from across France presenting clinical signs suggestive of leptospirosis were tested by micro-agglutination test between 2007 and 2017. We used a weighted average to determine the serogroup distributions according to the MAT results, considering cross reactions. Results: A total of 19,395 pig sera, mostly from Brittany, were tested, and 22.7 % were found to be positive for at least one Leptospira serogroup. In analysing the 4346 seropositive results for which the putative infective serogroup could be defined, we found that two serogroups out of ten were much more frequent than the others: Australis (48.5 %) and Icterohaemorrhagiae (38.2 %). Other serogroups, including Autumnalis, Panama, Ballum, Tarassovi, Sejroe, Grippotyphosa, Bataviae, and Pomona, were less common. Conclusion: Although data from diagnostic laboratories are prone to selection bias, using such a large amount of data provides a relevant overview of Leptospira distribution in space and time. Extracting epidemiological information with a standardized approach could be used for surveillance and support prophylactic strategies. Along the last decade, provide protection against the serogroups Australis and Icterohaemorrhagiae could prevent most of the clinical porcine leptospirosis in France.

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Brown rats are one of the most widespread urban species worldwide. Despite the nuisances they induce and their potential role as a zoonotic reservoir, knowledge on urban rat populations remains scarce. The main purpose of this study was to characterize an urban brown rat population from Chanteraines park (Hauts-de-Seine, France), with regards to haematology, population genetics, immunogenic diversity, resistance to anticoagulant rodenticides, and community of parasites. Haematological parameters were measured. Population genetics was investigated using 13 unlinked microsatellite loci. Immunogenic diversity was assessed for Mhc-Drb. Frequency of the Y139F mutation (conferring resistance to rodenticides) and two linked microsatellites were studied, concurrently with the presence of anticoagulant residues in the liver. Combination of microscopy and molecular methods were used to investigate the occurrence of 25 parasites. Statistical approaches were used to explore multiple parasite relationships and model parasite occurrence. Eighty-six rats were caught. The first haematological data for a wild urban R. norvegicus population was reported. Genetic results suggested high genetic diversity and connectivity between Chanteraines rats and surrounding population(s). We found a high prevalence (55.8%) of the mutation Y139F and presence of rodenticide residues in 47.7% of the sampled individuals. The parasite species richness was high (16). Seven potential zoonotic pathogens were identified, together with a surprisingly high diversity of Leptospira species (4). Chanteraines rat population is not closed, allowing gene flow and making eradication programs challenging, particularly because rodenticide resistance is highly prevalent. Parasitological results showed that co-infection is more a rule than an exception. Furthermore, the presence of several potential zoonotic pathogens, of which four Leptospira species, in this urban rat population raised its role in the maintenance and spread of these pathogens. Our findings should stimulate future discussions about the development of a long-term rat-control management program in Chanteraines urban park.

In Europe, the increasing number of nephropathia epidemica (NE) infections in humans, caused by Puumala virus carried by bank voles (Myodes glareolus), has triggered studies of environmental factors driving these infections. NE infections have been shown to occur in specific geographical areas characterized by environmental factors that influence the distribution and dynamics of host populations and virus persistence in the soil. Here, we review the influence of environmental conditions (including climate factors, food availability and habitat conditions) with respect to incidence in humans and seroprevalence in rodents, considering both direct and indirect transmission pathways. For each type of environmental factor, results and discrepancies between studies are presented and examined in the light of biological hypotheses. Overall, food availability and temperature appear to be the main drivers of host seroprevalence and NE incidence, but data quality and statistical approaches varied greatly among studies. We highlight the issues that now need to be addressed and suggest improvements for study design in regard to the current knowledge on hantavirus epidemiology.

Studies of the impact of parasites on host performance have mainly focused on body mass, a phenotypic trait that responds relatively slowly to the presence of parasites, and the expectedly faster response of physiological parameters has been mostly overlooked. We filled the gap by measuring the impact of endoparasites on four hematological/biochemical parameters (hematocrit, albumin, creatinine and fructosamine) in two contrasting free-living populations of roe deer. We generally found negative relationships between parasites and physiological parameters. Our findings also indicate little role of host sex on parasite impact and strongest parasite effects on young and senescent hosts.

In this study, using capture-mark-recapture (CMR), a common vole population was monitored for one year in an experimental study site dominated by meadows, in which field management followed a gradient of intensiveness. The aim was to estimate the demographic response to agricultural practices of the common vole. During the spring, the numbers captured were highest in the most intensively managed plots. After cereal harvesting, they were higher in meadows with the highest nitrogen input. No difference in survival was found among treatments. However, the pattern of transitions suggested that high mobility explained this result. Also, mechanical interventions like ploughing appeared to have powerful consequences for common vole survival. These results underline the critical role of dispersal and refuge habitats in the maintenance of populations of voles in agroecosystems. (c) 2013 Elsevier B.V. All rights reserved.

Key evolutionary events associated with invasion success are traditionally thought to occur in the introduced, rather than the native range of species. In the invasive ant Wasmannia auropunctata, however, a shift in reproductive system has been demonstrated within the native range, from the sexual non-dominant populations of natural habitats to the clonal dominant populations of human-modified habitats. Because abiotic conditions of human- modified habitats are hotter and dryer, we performed lab experiments on workers from a set of native and introduced populations, to investigate whether these ecological and genetic transitions were accompanied by a change in thermotolerance and whether such changes occurred before establishment in the introduced range. Thermotolerance levels were higher in native populations from human-modified habitats than in native populations from natural habitats, but were similar in native and introduced populations from human-modified habitats. Differences in thermotolerance could not be accounted for by differences in body size. A scenario based on local adaptation in the native range before introduction in remote areas represents the most parsimonious hypothesis to account for the observed phenotypic pattern. These findings highlight the importance of human land use in explaining major contemporary evolutionary changes.

The Congo forest mouse, Deomys ferrugineus, occurs readily in natural and human-altered habitats in the region of Kisangani (Democratic Republic of Congo). We studied survival and movement patterns of D. ferrugineus in both habitats. Capture-mark-recapture was used to study the effects of habitat on rodent life history both in primary rainforest and fallow land. Survival analyses taking into account trap-happiness effects were conducted using the program MARK. Abundance of D. ferrugineus was generally low within all our study grids, but it was lowest in fallow land compared to primary rainforest. Numbers of reproductively active females captured were not different between habitats but were larger during the rainy seasons. Daily movements of females, but not of males, were smaller in fallow land. Capture-markrecapture analyses showed recapture probabilities to vary highly between grids and years. Survival probability in the primary forest was higher than in fallow land with a difference of 0.084 over a period of four weeks. This is possibly linked to the higher abundance of the main food source (insects and termites); however, other explanations are discussed in the text.

The island syndrome is the name given to the particularities of the behavioural, morphological and demographical characteristics of island populations. As concerns demography, the island syndrome model states that densities and survival are greater in island than in mainland populations. Most previous studies aimed at confirming this prediction for small mammals have addressed species from the North Temperate Zone. Here, we tested the demographic expectations of the island syndrome using data gathered over two years for island and mainland populations of two African rodent species, Mastomys erytholeucus and Mastomys huberti, at two different sites in Senegal. Capture-Mark-Recapture methods allowing for variation in catchability of the individuals were used to yield estimates of both abundance (or density) and probability of survival and seniority (which is a demographic parameter inversely related to recruitment). As predicted from the island syndrome, survival and densities were indeed higher in island populations for the two study sites; however, only for the population with stronger island syndrome was the difference in survival biologically important. Estimates of the probability of seniority were similar for island and mainland populations at the two sites. Our findings provide support for the demographic expectations of the model of island syndrome in an Afrotropical context and thus confirm the general applicability of this syndrome while revealing differences according to particular insular situations. (C) 2012 Published by Elsevier Masson SAS.

Understanding where and how fast an infectious disease will spread during an epidemic is critical for its control. However, the task is a challenging one as numerous factors may interact and drive the spread of a disease, specifically when vector-borne diseases are involved. We advocate the use of simultaneous autoregressive models to identify environmental features that significantly impact the velocity of disease spread. We illustrate this approach by exploring several environmental factors influencing the velocity of bluetongue (BT) spread in France during the 2007-2008 epizootic wave to determine which ones were the most important drivers. We used velocities of BT spread estimated in 4,495 municipalities and tested sixteen covariates defining five thematic groups of related variables: elevation, meteorological-related variables, landscape-related variables, host availability, and vaccination. We found that ecological factors associated with vector abundance and activity (elevation and meteorological-related variables), as well as with host availability, were important drivers of the spread of the disease. Specifically, the disease spread more slowly in areas with high elevation and when heavy rainfall associated with extreme temperature events occurred one or two months prior to the first clinical case. Moreover, the density of dairy cattle was correlated negatively with the velocity of BT spread. These findings add substantially to our understanding of BT spread in a temperate climate. Finally, the approach presented in this paper can be used with other infectious diseases, and provides a powerful tool to identify environmental features driving the velocity of disease spread.

Many zoonotic diseases are caused by rodent-borne viruses. Major fluctuations in the transmission of these viruses have been related to large changes in reservoir host population numbers due to external factors. However, the impact of the pathogen itself on the demography of its reservoir host is often overlooked. We investigated the impact of Puumala virus (PUUV) on survival and reproductive maturation probability of its reservoir host, the bank vole (Myodes glareolus). Three years (2004-06) of data from nine independent sites in southern Belgium were collected and analyzed with a capture-mark-recapture (CMR) method that includes statistical correction for the variation in capture probability of voles. A multistate model based on four states of reproductive activity and PUUV immunoglobulin G (IgG) antibody status was used to estimate survival and probability of transition from one reproductive or infection state to another. Although survival estimates for reproductively active voles were similar between infected and noninfected individuals, PUUV infection in reproductively inactive voles decreased mean monthly survival by 14%. PUUV infection was associated with a threefold increase in the probability of reproductive maturation in bank voles. Moreover, the probability of PUUV IgG seroconversion was three times higher for reproductively active voles compared to reproductively inactive voles. Our model indicates that PUUV infection may alter bank vole population dynamics by affecting both survival and maturation in its host. Additional studies, using CMR methodology with shorter time intervals between trapping sessions and possibly a longer duration, are needed to confirm these findings.

So far, only a few studies have explicitly investigated the consequences of admixture for the adaptative potential of invasive populations. We addressed this question in the invasive ladybird Harmonia axyridis. After decades of use as a biological control agent against aphids in Europe and North America, H. axyridis recently became invasive in four continents and has now spread widely in Europe. Despite this invasion, a flightless strain is still sold as a biological control agent in Europe. However, crosses between flightless and invasive individuals yield individuals able to fly, as the flightless phenotype is caused by a single recessive mutation. We investigated the potential consequences of admixture between invasive and flightless biological control individuals on the invasion in France. We used three complementary approaches: (i) population genetics, (ii) a mate-choice experiment, and (iii) a quantitative genetics experiment. The invasive French population and the biological control strain showed substantial genetic differentiation, but there are no reproductive barriers between the two. Hybrids displayed a shorter development time, a larger size and a higher genetic variance for survival in starvation conditions than invasive individuals. We discuss the potential consequences of our results with respect to the invasion of H. axyridis in Europe.

The direct estimation and modeling of population growth rate from capture–recapture data has now seen a number of applications. However, the original model cannot accommodate heterogeneous capture probabilities. While studying a population of small mammals Peromyscus maniculatus, we became concerned that the peak of population size may be estimated too late in the year because of heterogeneous catchability. Hence, we developed a variation of the original model with a finite number of catchability classes. The results obtained with the new model are more in agreement with the known biology of this population. A bibliographic appendix and computer code are available online.