Publications by authors named "Sophie Rossi"

22 Publications

  • Page 1 of 1

Estimating disease prevalence and temporal dynamics using biased capture serological data in a wildlife reservoir: The example of brucellosis in Alpine ibex (Capra ibex).

Prev Vet Med 2021 Feb 26;187:105239. Epub 2020 Dec 26.

OFB - Office Français de la Biodiversité - Direction de la Recherche et Appui Scientifique - Unité Sanitaire de la Faune, Gap, France.

The monitoring of the disease prevalence in a population is an essential component of its adaptive management. However, field data often lead to biased estimates. This is the case for brucellosis infection of ibex in the Bargy massif (France). A test-and-cull program is being carried out in this area to manage the infection: captured animals are euthanized when seropositive, and marked and released when seronegative. Because this mountainous species is difficult to capture, field workers tend to focus the capture effort on unmarked animals. Indeed, marked animals are less likely to be infected, as they were controlled and negative during previous years. As the proportion of marked animals in the population becomes large, captured animals can no longer be considered as an unbiased sample of the population. We designed an integrated Bayesian model to correct this bias, by estimating the seroprevalence in the population as the combination of the separate estimates of the seroprevalence among unmarked animals (estimated from the data) and marked animals (estimated with a catalytic infection model, to circumvent the scarcity of the data). As seroprevalence may not be the most responsive parameter to management actions, we also estimated the proportion of animals in the population with an active bacterial infection. The actual infection status of captured animals was thus inferred as a function of their age and their level of antibodies, using a model based on bacterial cultures carried out for a sample of animals. Focusing on the population of adult females in the core area of the massif, i.e. with the highest seroprevalence, this observational study shows that seroprevalence has been divided by two between 2013 (51%) and 2018 (21%). Moreover, the likely estimated proportion of actively infected females in the same population, though very imprecise, has decreased from a likely estimate of 34% to less than 15%, suggesting that the management actions have been effective in reducing infection prevalence.
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http://dx.doi.org/10.1016/j.prevetmed.2020.105239DOI Listing
February 2021

Evaluation of a commercial ELISA for detection of epizootic haemorrhagic disease antibodies in domestic and wild ruminant sera.

Transbound Emerg Dis 2020 Nov 14;67(6):2475-2481. Epub 2020 May 14.

Laboratoire de Santé Animale d'Alfort, ANSES, ENVA, INRA, UMR 1161 VIROLOGIE, Université Paris Est, Maisons-Alfort, France.

Bluetongue (BT) and epizootic haemorrhagic disease (EHD) are vector-borne viral diseases affecting domestic and wild ruminants. Both are notifiable under OIE rules. BT and EHD viruses (BTV and EHDV) are closely related Orbiviruses with structural, antigenic and molecular similarities. Both viruses can produce analogous clinical signs in susceptible animals. Serological tests are commonly used for BT and EHD diagnosis and surveillance. Competitive ELISA (c-ELISA) is the most widely used serological test for the specific detection of BTV or EHDV viral protein 7 (VP7) antibodies (Abs). The specificity and sensitivity of the BTV c-ELISA kits available on the market are recognized for the detection of BTV Abs. Concerning EHD, a single commercial EHDV c-ELISA kit (ELISA A kit) commonly used for diagnosis in Europe and Africa was available between 2011 and 2018 but is now no longer on the market. In this study, we evaluated a new commercial c-ELISA to detect ruminant EHDV VP7 Abs in 2,199 serum samples from cattle, sheep, goats, wild deer and zoo animals. The results showed that this ELISA kit is specific and can detect the presence of IgG anti-EHDV VP7 with a very good diagnostic specificity and a satisfactory sensitivity in domestic ruminants, zoo animals and wild deer. Therefore, the evaluated c-ELISA can detect the introduction of EHDV into an area where BTV-seropositive domestic animals are present. The performance of this kit is similar to that of the c-ELISA A kit and can thus be used for diagnosis.
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http://dx.doi.org/10.1111/tbed.13586DOI Listing
November 2020

Genetic epidemiology of the Alpine ibex reservoir of persistent and virulent brucellosis outbreak.

Sci Rep 2020 03 10;10(1):4400. Epub 2020 Mar 10.

Université de Lyon, VetAgro Sup - Campus vétérinaire de Lyon, Marcy l'Étoile, France.

While it is now broadly accepted that inter-individual variation in the outcomes of host-pathogen interactions is at least partially genetically controlled, host immunogenetic characteristics are rarely investigated in wildlife epidemiological studies. Furthermore, most immunogenetic studies in the wild focused solely on the major histocompatibility complex (MHC) diversity despite it accounts for only a fraction of the genetic variation in pathogen resistance. Here, we investigated immunogenetic diversity of the Alpine ibex (Capra ibex) population of the Bargy massif, reservoir of a virulent outbreak of brucellosis. We analysed the polymorphism and associations with disease resistance of the MHC Class II Drb gene and several non-MHC genes (Toll-like receptor genes, Slc11A1) involved in the innate immune response to Brucella in domestic ungulates. We found a very low neutral genetic diversity and a unique MHC Drb haplotype in this population founded few decades ago from a small number of individuals. By contrast, other immunity-related genes have maintained polymorphism and some showed significant associations with the brucellosis infection status hence suggesting a predominant role of pathogen-mediated selection in their recent evolutionary trajectory. Our results highlight the need to monitor immunogenetic variation in wildlife epidemiological studies and to look beyond the MHC.
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http://dx.doi.org/10.1038/s41598-020-61299-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064506PMC
March 2020

Assessment of the impact of forestry and leisure activities on wild boar spatial disturbance with a potential application to ASF risk of spread.

Transbound Emerg Dis 2020 May 21;67(3):1164-1176. Epub 2019 Dec 21.

Research Unit for Epidemiology and Risk Analysis applied to veterinary sciences (UREAR-ULg), Centre of Fundamental and Applied Research for Animals and Health (FARAH), University of Liège, Liège, Belgium.

In Europe, African swine fever virus (ASFV) is one of the most threatening infectious transboundary diseases of domestic pigs and wild boar. In September 2018, ASF was detected in wild boar in the South of Belgium. France, as a bordering country, is extremely concerned about the ASF situation in Belgium, and an active preparedness is ongoing in the country. One of the questions raised by this situation relates to disturbing activities that may affect wild boar movements and their possible impact on the spread of ASFV. Despite evidence of disturbance related to hunting practices, there is a paucity of information on the impact of forestry and human leisure activities. To assess this impact on wild boar movements, a systematic review was first conducted but very few useful data were obtained. For this reason, an expert elicitation was carried out by the French Agency for Food, Environmental and Occupational Health & Safety in order to deal with this knowledge gap. A total of 30 experts originating from France and adjacent neighbouring countries (Spain, Belgium and Switzerland) were elicited about the relative importance of six factors of spatial disturbance of wild boar (noise, smell, invasion of space, modification of the environment, duration and frequency of the activity). Then, for each factor of disturbance, they were asked about the impact of 16 different commercial forestry and human leisure activities. A global weighted score was estimated in order to capture the variability of a wide range of territorial conditions and the uncertainty of expert elicitation. This estimate permitted ranking all 16 activities and aggregating them in three groups according to their potential for disturbance of wild boar, using a regression tree analysis. The results of this expert elicitation provide a methodological approach that may be useful for French and other European decision makers and stakeholders involved in the crisis management of ASF.
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http://dx.doi.org/10.1111/tbed.13447DOI Listing
May 2020

Brucella melitensis Rev.1 vaccination generates a higher shedding risk of the vaccine strain in Alpine ibex (Capra ibex) compared to the domestic goat (Capra hircus).

Vet Res 2019 Nov 27;50(1):100. Epub 2019 Nov 27.

Unité sanitaire de la Faune, Direction de la Recherche et de l'Expertise (DRE), Office National de la Chasse et de la Faune Sauvage (ONCFS), 5 rue de Saint-Thibaud, Saint-Benoît, 78610, Auffargis, France.

Epidemiological investigations implemented in wild and domestic ruminants evidenced a reservoir for Brucella in Capra ibex in the French Alps. Vaccination was considered as a possible way to control Brucella infection in this wildlife population. Twelve ibexes and twelve goats were allocated into four groups housed separately, each including six males or six non-pregnant females. Four to five animals were vaccinated and one or two animals were contact animals. Half of the animals were necropsied 45 days post-vaccination (pv), and the remaining ones at 90 days pv. Additional samples were collected 20 and 68 days pv to explore bacterial distribution in organs and humoral immunity. Neither clinical signs nor Brucella-specific lesions were observed and all vaccinated animals seroconverted. Brucella distribution and antibody profiles were highly contrasted between both species. Proportion of infected samples was significantly higher in ibex compared to goats and decreased between 45 and 90 days pv. Two male ibex presented urogenital excretion at 20 or 45 days pv. The bacterial load was higher 45 days in ibexes compared to goats, whereas it remained moderate to low 90 days pv in both species with large variability between animals. In this experiment, differences between species remained the main source of variation, with low impact of other individual factors. To conclude, multiplicative and shedding capacity of Rev.1 was much higher in ibex compared to goats within 90 days. These results provide initial information on the potential use in natura of a commercial vaccine.
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http://dx.doi.org/10.1186/s13567-019-0717-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6882340PMC
November 2019

Red deer () Did Not Play the Role of Maintenance Host for Bluetongue Virus in France: The Burden of Proof by Long-Term Wildlife Monitoring and Snapshots.

Viruses 2019 09 27;11(10). Epub 2019 Sep 27.

UMR Virologie, INRA, Ecole Nationale Vétérinaire d'Alfort, laboratoire de santé animale d'Alfort, ANSES, Université Paris-Est, 94700 Maisons-Alfort, France, (C.V.).

Bluetongue virus (BTV) is a -borne pathogen infecting both domestic and wild ruminants. In Europe, the Red Deer () (RD) is considered a potential BTV reservoir, but persistent sylvatic cycle has not yet been demonstrated. In this paper, we explored the dynamics of BTV1 and BTV8 serotypes in the RD in France, and the potential role of that species in the re-emergence of BTV8 in livestock by 2015 (i.e., 5 years after the former last domestic cases). We performed 8 years of longitudinal monitoring (2008-2015) among 15 RD populations and 3065 individuals. We compared communities and feeding habits within domestic and wild animal environments (51,380 samples). diversity (>30 species) varied between them, but bridge-species able to feed on both wild and domestic hosts were abundant in both situations. Despite the presence of competent vectors in natural environments, BTV1 and BTV8 strains never spread in RD along the green corridors out of the domestic outbreak range. Decreasing antibody trends with no PCR results two years after the last domestic outbreak suggests that seropositive young RD were not recently infected but carried maternal antibodies. We conclude that RD did not play a role in spreading or maintaining BTV in France.
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http://dx.doi.org/10.3390/v11100903DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6832957PMC
September 2019

High Shedding Potential and Significant Individual Heterogeneity in Naturally-Infected Alpine ibex () With .

Front Microbiol 2018 28;9:1065. Epub 2018 May 28.

Wildlife Diseases Unit, French Hunting and Wildlife Agency (ONCFS), Gap, France.

Wildlife reservoirs of infectious diseases raise major management issues. In Europe, brucellosis has been eradicated in domestic ruminants from most countries and wild ruminants have not been considered important reservoirs so far. However, a high prevalence of infection has been recently identified in a French population of Alpine ibex (), after the emergence of brucellosis was confirmed in a dairy cattle farm and two human cases. This situation raised the need to identify the factors driving the persistence of infection at high prevalence levels in this ibex population. In the present paper, we studied the shedding pattern of in ibex from Bargy Massif, French Alps. Bacteriological examinations (1-15 tissues/samples per individual) were performed on 88 seropositive, supposedly infected and euthanized individuals. Among them, 51 (58%) showed at least one positive culture, including 45 ibex with at least one isolation from a urogenital sample or a lymph node in the pelvic area (active infection in organs in the pelvic area). Among these 45 ibex, 26 (30% of the total number of necropsied animals) showed at least one positive culture for a urogenital organ and were considered as being at risk of shedding the bacteria at the time of capture. We observed significant heterogeneity between sex-and-age classes: seropositive females were most at risk to excrete before the age of 5 years, possibly corresponding to abortion during the first pregnancy following infection such as reported in the domestic ruminants. The high shedding potential observed in young females may have contributed to the self-sustained maintenance of infection in this population, whereas males are supposed to play a role of transmission between spatial units through venereal transmission during mating. This heterogeneity in the shedding potential of seropositive individuals should be considered in the future to better evaluate management scenarios in this system as well as in others.
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http://dx.doi.org/10.3389/fmicb.2018.01065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5985404PMC
May 2018

Serological survey in wild boar (Sus scrofa) in Switzerland and other European countries: Sarcoptes scabiei may be more widely distributed than previously thought.

BMC Vet Res 2018 Mar 27;14(1):117. Epub 2018 Mar 27.

Centre for Fish and Wildlife Health, Vetsuisse Faculty, University of Bern, Länggass-Str. 122, Postfach, 3001, Bern, Switzerland.

Background: Sarcoptic mange has recently emerged in wild boar in Switzerland, raising the question of the origin of the infection. The main aim of this study was to assess the extent of exposure of the wild boar populations to Sarcoptes scabiei in Switzerland, prior to and after the detection of mange cases, to determine whether the mite has been recently introduced into the populations concerned. We performed a serological survey using a commercially available ELISA and 1056 archived blood samples of free-ranging wild boar from Switzerland. To facilitate the interpretation of the obtained data, we additionally estimated seroprevalence in wild boar populations of four other European countries (1060 samples), both from areas with confirmed clinical cases of mange and from areas without reported cases in wild boar. Lastly, we revised the evaluation of the commercial ELISA when used with wild boar sera.

Results: Seropositive reactions were observed for samples from all five countries and from 15 of the 16 study areas. The obtained apparent seroprevalences ranged from 0.0% (0/82; 95% confidence interval [CI]: 0.0-4.4) to 17.4% (8/46; 95% CI: 7.8-31.4). Wild boar from study areas with known clinical cases and those ≤60 kg were four times more likely to be seropositive than wild boar from areas without reported cases and > 60 kg, respectively. Optical density values did not differ between the two types of study areas among seropositive samples but were significantly lower among seronegative samples from areas without than from areas with clinical cases. No difference was observed between the two sampling periods in Switzerland. The revised ELISA specificity was 96.8% (984/1017; 95% CI: 95.5-97.7) when wild boar from areas without history of mange were considered truly negative.

Conclusions: Seropositivity to S. scabiei is more frequent and occurs over a larger geographic range than expected. Data suggest that the parasite is endemic within the wild boar populations of Switzerland and other European countries but that its presence is not necessarily associated with disease occurrence. Extrinsic factors which trigger disease emergence in infected populations remain to be investigated. The applied ELISA represents a promising tool for future studies.
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http://dx.doi.org/10.1186/s12917-018-1430-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872548PMC
March 2018

Aujeszky's Disease and Hepatitis E Viruses Transmission between Domestic Pigs and Wild Boars in Corsica: Evaluating the Importance of Wild/Domestic Interactions and the Efficacy of Management Measures.

Front Vet Sci 2018 24;5. Epub 2018 Jan 24.

Unité Virologie Immunologie Porcines, Laboratoire de Ploufragran/Plouzané, ANSES, Ploufragan, France.

Wildlife species as reservoirs of infectious pathogens represent a serious constraint in the implementation of disease management strategies. In the Mediterranean island of Corsica, the dynamics of hepatitis E virus (HEV) and Aujeszky's disease virus (ADV) are suspected to be influenced by interactions between wild and domestic pigs. To improve our understanding of these influences, we first compared the seroprevalences of both viruses in domestic pig populations from different locations with contrasted levels of wild-domestic interactions, ADV vaccination, biosafety, and farm husbandry. Second, we performed an analysis at a more restricted geographical scale, to assess the matching of ADV or HEV prevalence between sympatric wild boar and outdoor pig farms most exposed to interactions with wildlife. Logistic models were adjusted to the observed data. A high seroprevalence of HEV (>80%) and ADV (40%) in pigs, with no significant difference according to the region, confirms that both pathogens are enzootic in Corsica. Vaccination against ADV had a strong protective effect, even when performed voluntarily by farmers. Farm biosafety had an additional effect on pigs' exposure, suggesting that contact between wild boars and pigs were involved in disease transmission. A strong correlation in HEV seroprevalence was observed between pigs and wild boars that were in close contact, and significantly lower seroprevalence was observed in pigs when they had little contact with wild boars due to spatial segregation. These results suggest a regular HEV circulation between sympatric wild boar and domestic pigs. The high HEV seroprevalence observed in domestic pigs (>80%) suggests a spillover of the virus from domestic to wild populations through environmental contamination, but this hypothesis has to be confirmed. Conversely, even though avoiding sows' release on pasture during estrus showed some protecting effect in the free ranging pig farms regarding ADV, ADV seroprevalence was not dependent on the swine populations (wild or domestic) or on the wild-domestic spatial overlap, suggesting two quasi-separate enzootic cycles. This information will prove useful for designing more efficient disease management strategies in Corsica and similar contexts.
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http://dx.doi.org/10.3389/fvets.2018.00001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5787731PMC
January 2018

Sociospatial structure explains marked variation in brucellosis seroprevalence in an Alpine ibex population.

Sci Rep 2017 11 15;7(1):15592. Epub 2017 Nov 15.

Office National de la Chasse et de la Faune Sauvage, Unité Sanitaire de la Faune, 5 allée de Béthléem, F-38610, Gières, France.

In a context of (re)emerging infectious diseases with wildlife reservoirs, understanding how animal ecology shapes epidemiology is a key issue, particularly in wild ungulates that share pathogens with domestic herbivores and have similar food requirements. For the first time in Europe, brucellosis (Brucella melitensis), a virulent zoonosis, persisted in an Alpine ibex (Capra ibex) population and was transmitted to cattle and humans. To better understand disease dynamics, we investigated the relationships between the spatial ecology of ibex and the epidemiology of brucellosis. Combining home range overlap between 37 GPS-collared individuals and visual observations of 148 visually-marked individuals monitored during the 2013-2016 period, we showed that females were spatially segregated in at least 4 units all year round, whereas males were more prone to move between female units, in particular during the rutting period. In addition to ibex age, the spatial structure in females largely contributed to variation in seroprevalence in the whole population. These results suggest that non-sexual routes are the most likely pathways of intraspecific transmission, crucial information for management. Accounting for wildlife spatial ecology was hence decisive in improving our ability to better understand this health challenge involving a wildlife reservoir.
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http://dx.doi.org/10.1038/s41598-017-15803-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5688143PMC
November 2017

How to survey classical swine fever in wild boar (Sus scrofa) after the completion of oral vaccination? Chasing away the ghost of infection at different spatial scales.

Vet Res 2016 Jan 25;47:21. Epub 2016 Jan 25.

ONCFS, Office National de la Chasse et de la Faune Sauvage, Unité Sanitaire de la Faune, Micropolis, la Bérardie, Belle Aureille, 05000, Gap, France.

Oral mass vaccination (OMV) is considered as an efficient strategy for controlling classical swine fever (CSF) in wild boar. After the completion of vaccination, the presence of antibodies in 6-12 month-old hunted wild boars was expected to reflect a recent CSF circulation. Nevertheless, antibodies could also correspond to the long-lasting of maternal antibodies. This paper relates an experience of surveillance which lasted 4 years after the completion of OMV in a formerly vaccinated area, in north-eastern France (2010-2014). First, we conducted a retrospective analysis of the serological data collected in 6-12 month-old hunted wild boars from 2010 up to 2013, using a spatial Bayesian model accounting for hunting data autocorrelation and heterogeneity. At the level of the whole area, seroprevalence in juvenile boars decreased from 28% in 2010-2011 down to 1% in 2012-2013, but remained locally high (above 5%). The model revealed the existence of one particular seroprevalence hot-spot where a longitudinal survey of marked animals was conducted in 2013-2014, for deciphering the origin of antibodies. Eleven out of 107 captured piglets were seropositive when 3-4 months-old, but their antibody titres progressively decreased until 6-7 months of age. These results suggest piglets were carrying maternal antibodies, few of them carrying maternal antibodies lasting until the hunting season. Our study shows that OMV may generate confusion in the CSF surveillance several years after the completion of vaccination. We recommend using quantitative serological tools, hunting data modelling and capture approaches for better interpreting serological results after vaccination completion. Surveillance perspectives are further discussed.
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http://dx.doi.org/10.1186/s13567-015-0289-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4727256PMC
January 2016

Evolution and molecular epidemiology of classical swine fever virus during a multi-annual outbreak amongst European wild boar.

J Gen Virol 2016 Mar 18;97(3):639-645. Epub 2015 Dec 18.

Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, 17493 Greifswald-Insel Riems, Germany.

Classical swine fever is a viral disease of pigs that carries tremendous socio-economic impact. In outbreak situations, genetic typing is carried out for the purpose of molecular epidemiology in both domestic pigs and wild boar. These analyses are usually based on harmonized partial sequences. However, for high-resolution analyses towards the understanding of genetic variability and virus evolution, full-genome sequences are more appropriate. In this study, a unique set of representative virus strains was investigated that was collected during an outbreak in French free-ranging wild boar in the Vosges-du-Nord mountains between 2003 and 2007. Comparative sequence and evolutionary analyses of the nearly full-length sequences showed only slow evolution of classical swine fever virus strains over the years and no impact of vaccination on mutation rates. However, substitution rates varied amongst protein genes; furthermore, a spatial and temporal pattern could be observed whereby two separate clusters were formed that coincided with physical barriers.
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http://dx.doi.org/10.1099/jgv.0.000376DOI Listing
March 2016

Controlling of CSFV in European wild boar using oral vaccination: a review.

Front Microbiol 2015 23;6:1141. Epub 2015 Oct 23.

Laboratoire de Ploufragan/Plouzané, Unité Virologie Immunologie Porcines, Anses Ploufragan, France.

Classical swine fever (CSF) is among the most detrimental diseases for the swine industry worldwide. Infected wild boar populations can play a crucial role in CSF epidemiology and controlling wild reservoirs is of utmost importance for preventing domestic outbreaks. Oral mass vaccination (OMV) has been implemented to control CSF in wild boars and limit the spill over to domestic pigs. This retrospective overview of vaccination experiences illustrates the potential for that option. The C-strain live vaccine was confirmed to be highly efficacious and palatable baits were developed for oral delivery in free ranging wild boars. The first field trials were performed in Germany in the 1990's and allowed deploying oral baits at a large scale. The delivery process was further improved during the 2000's among different European countries. Optimal deployment has to be early regarding disease emergence and correctly designed regarding the landscape structure and the natural food sources that can compete with oral baits. OMV deployment is also highly dependent on a local veterinary support working closely with hunters, wildlife and forestry agencies. Vaccination has been the most efficient strategy for CSF control in free ranging wild boar when vaccination is wide spread and lasting for a sufficient period of time. Alternative disease control strategies such as intensified hunting or creating physical boundaries such as fences have been, in contrast, seldom satisfactory and reliable. However, monitoring outbreaks has been challenging during and after vaccination deployment since OMV results in a low probability to detect virus-positive animals and the live-vaccine currently available does not allow serological differentiation of infected from vaccinated animals. The development of a new marker vaccine and companion test is thus a promising option for better monitoring outbreaks during OMV deployment as well as help to better determine when to stop vaccination efforts. After rabies in red fox, the use of OMV against CSF in European wild boar can be considered as a second example of successful disease control in wildlife. The 30 years of disease control experience included in this review may provide options for improving future disease management within wild populations.
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http://dx.doi.org/10.3389/fmicb.2015.01141DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4615961PMC
November 2015

Evaluation of a Commercial ELISA for the Detection of Antibodies to Sarcoptes scabiei in Wild Boar (Sus scrofa).

J Wildl Dis 2015 Jul;51(3):729-33

1  Centre for Fish and Wildlife Health, Vetsuisse Faculty, University of Bern, Länggass-Str. 122, Postfach 8466, 3001 Bern, Switzerland.

Sarcoptic mange occurs in free-ranging wild boar (Sus scrofa) but has been poorly described in this species. We evaluated the performance of a commercial indirect enzyme-linked immunosorbent assay (ELISA) for serodiagnosis of sarcoptic mange in domestic swine when applied to wild boar sera. We tested 96 sera from wild boar in populations without mange history ("truly noninfected") collected in Switzerland between December 2012 and February 2014, and 141 sera from free-ranging wild boar presenting mange-like lesions, including 50 live animals captured and sampled multiple times in France between May and August 2006 and three cases submitted to necropsy in Switzerland between April 2010 and February 2014. Mite infestation was confirmed by skin scraping in 20 of them ("truly infected"). We defined sensitivity of the test as the proportion of truly infected that were found ELISA-positive, and specificity as the proportion of truly noninfected that were found negative. Sensitivity and specificity were 75% and 80%, respectively. Success of antibody detection increased with the chronicity of lesions, and seroconversion was documented in 19 of 27 wild boar sampled multiple times that were initially negative or doubtful. In conclusion, the evaluated ELISA has been successfully applied to wild boar sera. It appears to be unreliable for early detection in individual animals but may represent a useful tool for population surveys.
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http://dx.doi.org/10.7589/2014-09-222DOI Listing
July 2015

Schmallenberg virus infection among red deer, France, 2010-2012.

Emerg Infect Dis 2014 Jan;20(1):131-4

Schmallenberg virus infection is emerging in European domestic and wild ruminants. We investigated the serologic status of 9 red deer populations to describe virus spread from September 2010 through March 2012 among wildlife in France. Deer in 7 populations exhibited seropositivity, with an average seroprevalence of 20%.
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http://dx.doi.org/10.3201/eid2001.130411DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3884713PMC
January 2014

Bayesian modelling of hunting data may improve the understanding of host-parasite systems: wild boar diseases and vaccination as an example.

J Theor Biol 2014 Feb 21;343:32-43. Epub 2013 Nov 21.

Office national de la chasse et de la faune sauvage, Micropolis, F-05000 Gap, France. Electronic address:

Wildlife diseases are often studied using hunting data. In such studies, inferences about diseases are often made by comparing raw disease prevalence levels, ignoring complications like stochasticity in recruitment. We carried out a field trial to study the effectiveness of oral vaccination of wild boar (Sus scrofa) against classical swine fever (CSF) in the Vosges mountains (Northeastern France) for 3 years (2008-2010). Since August 2004, hunters had carried out three vaccination sessions per year in spring, summer and autumn. During our study period, we determined whether each wild boar hunted in our study area was immunized or not against CSF. We used a Bayesian approach to model the changes in the proportion of vaccinated animals in the population of young animals (i.e., <12 months old). This approach allowed to disentangle the effects of the birth peaks (leading to a decrease) and of both the vaccination sessions and natural infection (leading to an increase) on this proportion. We thus inferred, at the individual level, the probability that a non-immunized animal became vaccinated after a particular session. There was a high between-year variability in the effectiveness of the vaccination: the observed patterns were similar in 2008 and 2010, but 2009 was characterized by an overall greater effectiveness of the vaccination. Within a particular year, the spring vaccination session was more effective than the autumn session, probably because of the higher food availability in autumn that render the vaccination places less attractive to the animals. The vaccination effectiveness was rather low in summer, except in 2009, probably because of higher age identification error this year. This model also highlighted an immunisation of animals occurring outside vaccination periods, which suggests either the presence of the CSF virus in our study area, or the consumption of the vaccine outside the vaccination sessions. Finally, we observed a high spatial variability of the probability of vaccination. The effectiveness of the vaccination was indeed strongly related to both the distribution of the forests and the distribution of the vaccination places in our study area. This study highlights an optimal vaccination effort of 1.25 places per km(2) to maximize the proportion of immune wild boar in that area.
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http://dx.doi.org/10.1016/j.jtbi.2013.11.011DOI Listing
February 2014

Innate immunity correlates with host fitness in wild boar (Sus scrofa) exposed to classical swine fever.

PLoS One 2013 18;8(11):e79706. Epub 2013 Nov 18.

Office national de la chasse et de la faune sauvage, unité sanitaire de la faune, Gap, France.

Constitutive humoral immunity (CHI) is thought to be a first-line of protection against pathogens invading vertebrate hosts. However, clear evidence that CHI correlates with host fitness in natural conditions is still lacking. This study explores the relationship between CHI, measured using a haemagglutination-haemolysis assay (HAHL), and resistance to classical swine fever virus (CSFV) among wild boar piglets. The individual dynamics of HAHL during piglet growth was analysed, using 423 serum samples from 92 piglets repeatedly captured in the absence of CSFV (in 2006) within two areas showing contrasting food availability. Natural antibody levels increased with age, but, in the youngest piglets antibody levels were higher in individuals from areas with the highest food availability. Complement activity depended on natural antibody levels and piglets' body condition. In the presence of CSFV (i.e., in 2005 within one area), serum samples from piglets that were repeatedly captured were used to assess whether piglet HAHL levels affected CSFV status at a later capture. The correlation between CHI and resistance to CSFV was tested using 79 HAHL measures from 23 piglets captured during a CSFV outbreak. Both natural antibodies and complement activity levels measured at a given time correlated negatively to the subsequent probability of becoming viremic. Finally, capture-mark-recapture models showed that piglets with medium/high average complement activity, independently of their age, were significantly less at risk of becoming viremic and more likely to develop a specific immune response than piglets with low complement activity. Additionally, piglets with high average complement activity showed the highest survival prospects. This study provides evidence linking CHI to individual fitness within a natural mammal population. The results also highlight the potential of HAHL assays to explore the dynamics and co-evolution between wildlife mammal hosts and blood-borne parasites interacting with the CHI.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0079706PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3832544PMC
July 2014

Iophenoxic acid derivatives as markers of oral baits to wildlife. New tools for their detection in tissues of a game species and safety considerations for human exposure.

Environ Sci Pollut Res Int 2013 May 22;20(5):2893-904. Epub 2012 Sep 22.

Game and Wildlife Agency (Office national de chasse et de faune sauvage), Wildlife Sanitary Unit (unité sanitaire de faune), 67150 St. Benoist, France.

The bait-marker iophenoxic acid (IPA) and its derivatives are increasingly used for evaluating and optimizing the cost-effectiveness of baiting campaigns on wildlife, particularly on game species such as the wild boar. We aimed to determine whether concentrations of the three main IPA derivatives ethyl, methyl and propyl-IPA measured on thoracic liquid extracts (TLE) of hunted wild boars may be representative of two exposure doses, 40 and 200 mg, from 20 to 217 days after ingestion. Then we developed a method of detection of the three IPA derivatives by LC/ESI-MS-MS in muscle and liver to evaluate the suitability of these two other tissues for monitoring the marked bait consumption and for measuring available residues in the meat of marked animals. Three semi-captive wild boars received 40 mg of each IPA derivative, three received 200 mg, and three, as controls, did not receive IPA. Blood serum was sampled 20, 197 or 217 days after IPA exposure according to animals and to the derivative. Wild boars were shot by gun after the different times of serum sampling times, and TLE, muscle and liver were sampled. Our results suggest that TLE is not a relevant tissue for quantitatively expressing IPA exposure. Due to interference, no analytical method was validated on TLE containing digestive material. On the other hand, quantifications in the muscle and particularly in the liver could discriminate wild boars that had ingested the two IPA doses from 20 days until 7 months after exposure, especially for the two long term markers ethyl and propyl-IPA. So IPA quantifications in the liver sampled on hunted animals appear to be a reliable tool for monitoring bait consumption in the field at a large scale. Nevertheless, whatever the ingested dose, ethyl- and propyl-IPA concentrations measured in the muscle and the liver of tested animals until 217 days after exposure, remained higher than 0.01 mg/kg, the Maximal Residue Limit (MRL) is recommended for molecules for which no toxicological data are available. Based on the range of IPA residues available in these two tissues, implications for humans consuming marked animals are discussed.
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http://dx.doi.org/10.1007/s11356-012-1172-xDOI Listing
May 2013

Environmental factors associated with the seroprevalence of Toxoplasma gondii in Wild Boars (Sus scrofa), France.

Ecohealth 2012 Sep 21;9(3):303-9. Epub 2012 Jul 21.

INRA, UR346, Saint-Genes-Champanelle, France.

Toxoplasma gondii is a protozoan parasite infecting humans and animals. Wild boars Sus scrofa are a potential source of human infection and an appropriate biological model for analyzing T. gondii dynamics in the environment. Here, we aimed to identify environmental factors explaining the seroprevalence of toxoplasmosis in French wild boar populations. Considering 938 individuals sampled from 377 'communes', overall seroprevalence was 23% (95% confidence interval: [22-24]). Using a Poisson regression, we found that the number of seropositive wild boars detected per 'commune' was positively associated with the presence of European wildcats (Felis silvestris) and moderate winter temperatures.
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http://dx.doi.org/10.1007/s10393-012-0786-2DOI Listing
September 2012

New insights on the management of wildlife diseases using multi-state recapture models: the case of classical swine fever in wild boar.

PLoS One 2011 22;6(9):e24257. Epub 2011 Sep 22.

Unité Sanitaire de la Faune, Office National de la Chasse et de la Faune Sauvage, Gap, France.

Background: The understanding of host-parasite systems in wildlife is of increasing interest in relation to the risk of emerging diseases in livestock and humans. In this respect, many efforts have been dedicated to controlling classical swine fever (CSF) in the European Wild Boar. But CSF eradication has not always been achieved even though vaccination has been implemented at a large-scale. Piglets have been assumed to be the main cause of CSF persistence in the wild since they appeared to be more often infected and less often immune than older animals. However, this assumption emerged from laboratory trials or cross-sectional surveys based on the hunting bags.

Methodology/principal Findings: In the present paper we conducted a capture-mark-recapture study in free-ranging wild boar piglets that experienced both CSF infection and vaccination under natural conditions. We used multi-state capture recapture models to estimate the immunization and infection rates, and their variations according to the periods with or without vaccination. According to the model prediction, 80% of the infected piglets did not survive more than two weeks, while the other 20% quickly recovered. The probability of becoming immune did not increase significantly during the summer vaccination sessions, and the proportion of immune piglets was not higher after the autumn vaccination.

Conclusions/significance: Given the high lethality of CSF in piglets highlighted in our study, we consider unlikely that piglets could maintain the chain of CSF virus transmission. Our study also revealed the low efficacy of vaccination in piglets in summer and autumn, possibly due to the low palatability of baits to that age class, but also to the competition between baits and alternative food sources. Based on this new information, we discuss the prospects for the improvement of CSF control and the interest of the capture-recapture approach for improving the understanding of wildlife diseases.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0024257PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3178526PMC
January 2012

Adaptation of a species-specific multiplex PCR assay for the identification of blood meal source in Culicoides (Ceratopogonidae: Diptera): applications on Palaearctic biting midge species, vectors of Orbiviruses.

Infect Genet Evol 2011 Jul 12;11(5):1103-10. Epub 2011 Apr 12.

Cirad, UMR Contrôle des maladies, F-34398 Montpellier Cedex 5, France.

Culicoides are small biting midges involved worldwide in the transmission of bluetongue and African horse sickness viruses. Feeding behaviours of Palaearctic biting midge species and their spatio-temporal dynamics remain unclear at the specific level. Three multiplex species-specific PCR-based assays were developed and used to identify blood meal source of engorged females of Palaearctic midge species of veterinary interest. Species-specific primers of potential hosts from livestock, domestic animals and wildlife (cattle, goat, sheep, red deer, roe deer, chamois, dog, pig, cat, horse) were designed and multiplexed from the mitochondrial cytochrome b gene. The assays also make possible to identify whether multiple blood meals have been taken. The first results from several Culicoides populations sampled in France highlight the utility of this valuable diagnostic tool combined with species identification assays, and suggest that most of the Culicoides species may have an opportunistic feeding behaviour regarding the host distribution and density. Noteworthy is the peculiar trophic behaviour of Culicoides chiopterus showing clear trends to cattle. Information on host preference and feeding behaviours are crucial for a better understanding of vector-host interactions and disease epidemiology.
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http://dx.doi.org/10.1016/j.meegid.2011.04.002DOI Listing
July 2011

Long-term monitoring of classical swine fever in wild boar (Sus scrofa sp.) using serological data.

Vet Res 2005 Jan-Feb;36(1):27-42

Ecole Nationale Vétérinaire de Lyon, Unité Microbiologie, Pathologie infectieuse et Epidémiologie, 1 avenue Bourgelat, BP 83, 69280 Marcy-l'Etoile, France.

In the European Community, epizootics of classical swine fever (CSF) in the wild boar (Sus scrofa) are compulsorily monitored because transmission may occur between wild boars and domestic pigs, causing heavy economic losses to the pork industry. The estimation of incidence in populations of wild boars is generally based on viroprevalence. However, viral isolation becomes rare when the incidence is low because the virus cannot be detected for more than a few weeks following infection. On the contrary, seroprevalence is detectable at low incidence levels, because antibodies can be detected for the lifetime of the infected animal. We thus attempted to analyse the long-term evolution of CSF incidence using serological data. The data came from France, where CSF had been monitored from 1992 to 2002, and where the virus has not been detected since 1997. We assumed that the overall seroprevalence would estimate the proportion of immune wild boars, that seroprevalence in juveniles would approximate incidence and that seroprevalence in different age classes would show the evolution of incidence in a given cohort. Spatial and temporal trends of incidence and seroprevalence were explored using logistic modelling and the spatial trend was analysed using polynomial regression. In 1992, incidence peaked in the northern area. After 1993, incidence decreased but remained the highest in the northern area. After 2000, no seropositive juvenile was observed, suggesting the extinction of the epizootic. Our results support the reliability of serological monitoring since it allowed a longer detection of viral transmission and provided more information on the spatio-temporal evolution of incidence than did viral isolation. We advocate that the highest persistence of infection in northeastern France is not independent from infection persistence in Reinland-Pfalz (Germany). Such persistence may be due to favourable local conditions and/or the social organisation of wild boars.
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http://dx.doi.org/10.1051/vetres:2004050DOI Listing
February 2005