La Peste Porcine Africaine (PPA) est une maladie infectieuse émergente des suidés domestiques et ... more La Peste Porcine Africaine (PPA) est une maladie infectieuse émergente des suidés domestiques et sauvages. Cette maladie contagieuse entre suidés, non transmissible à l’Homme, est à l’origine d’un syndrome hémorragique souvent fatal chez les porcs domestiques et les sangliers. L'épizootie qui sévit actuellement en Europe et en Asie a débuté en Géorgie en 2007. La souche virale impliquée, très virulente, appartenant au génotype II, est très résistante dans les viandes et l’environnement. Toutes les souches isolées en Europe comme en Asie dérivent d’une même introduction, même si le virus a évolué vers des formes moins virulentes dans certaines populations de sangliers très localisées. Depuis la Géorgie, le virus s'est propagé dans tout le Caucase et la Fédération de Russie, puis en Ukraine et en Biélorussie en 2013. En janvier 2014, la PPA a atteint les frontières orientales de l'Union européenne et s’est propagée dans les trois États baltes et en Pologne très largement d...
In order to assess influenza D virus (IDV) infections in swine in France, reference reagents were... more In order to assess influenza D virus (IDV) infections in swine in France, reference reagents were produced in specific pathogen free pigs to ensure serological and virological analyses. Hemagglutination inhibition (HI) assays were carried out on 2090 domestic pig sera collected in 2012–2018 in 102 farms. Only 31 sera from breeding sows sampled in 2014–2015 in six farrow-to-finish herds with respiratory disorders contained IDV-specific antibodies. In two of them, within-herd percentage of positive samples (73.3% and 13.3%, respectively) and HI titers (20–160) suggested IDV infections, but virus persistence was not confirmed following new sampling in 2017. All growing pigs tested seronegative, whatever their age and the sampling year. Moreover, PB1-gene RT-qPCR performed on 452 nasal swabs taken in 2015–2018 on pigs with acute respiratory syndrome (137 farms) gave negative results. In Corse, a Mediterranean island where pigs are mainly bred free-range, 2.3% of sera (n = 177) sampled o...
In Europe, modified live vaccines (MLV) are commonly used to control porcine reproductive and res... more In Europe, modified live vaccines (MLV) are commonly used to control porcine reproductive and respiratory syndrome virus (PRRSV) infection. However, they have been associated with safety issues such as reversion to virulence induced by mutation and/or recombination. On a French pig farm, we identified a field recombinant strain derived from two PRRSV-1 MLV (MLV1). As a result, we aimed to evaluate its clinical, virological, and transmission parameters in comparison with both parental strains. Three groups with six pigs in each were inoculated with either one of the two MLV1s or with the recombinant strain; six contact pigs were then added into each inoculated group. The animals were monitored daily for 35 days post-inoculation (dpi) for clinical symptoms; blood samples and nasal swabs were collected twice a week. PRRS viral load in inoculated pigs of recombinant group was higher in serum, nasal swabs, and tonsils in comparison with both vaccine groups. The first viremic contact pig ...
Hepatitis E virus (HEV) is an emerging zoonotic pathogen mainly transmitted via food in developed... more Hepatitis E virus (HEV) is an emerging zoonotic pathogen mainly transmitted via food in developed countries, and for which domestic pigs are recognised as the main reservoir. To implement an efficient HEV surveillance and control plan in the pig production sector, it is first necessary to assess the level of knowledge of pig-farming main actors about this pathogen. To this aim, an online survey was conducted between September and October 2017 to evaluate pig farmers' and veterinarians' knowledge about HEV epidemiology and its zoonotic potential. The questionnaire was filled in by 383 pig farmers and 46 pig veterinarians. Of this population, 77.8% of farmers and 8.7% of veterinarians had never heard of HEV. Our results highlight knowledge gaps among responding farmers, especially regarding the clinical and epidemiological features of HEV, while veterinarians appear to be well-informed about this pathogen. These findings indicate significant room for further improvement and th...
Corsica is a mountainous French island in the north-western Mediterranean Sea. It is a rural area... more Corsica is a mountainous French island in the north-western Mediterranean Sea. It is a rural area, where pig farming is a major economic activity. Although no acute respiratory outbreaks due to swine influenza A viruses (swIAVs) have ever been reported in this free-ranging pig breeding system, influenza A viruses (IAVs) could be circulating within this pig population. A serological study was conducted as a first approach to domestic pigs and wild boars. Serum samples from 543 pigs raised on 91 different farms were collected during the 2013-2014 slaughtering season, and 279 sera from wild boars were obtained over four hunting seasons (between 2009 and 2014). They were first analysed by ELISA and then IAV positive and doubtful sera were subjected to haemagglutination inhibition tests using antigens representative of the four major enzootic swIAV lineages in Europe, i.e. avian-like swine H1N1 (H1N1), pandemic-like swine H1N1 (H1N1pdm), H1N2 and H3N2. According to the ELISA results, 26....
Numerous viruses, mostly in mixed infections, have been associated worldwide with poult enteritis... more Numerous viruses, mostly in mixed infections, have been associated worldwide with poult enteritis complex (PEC). In 2008 a coronavirus (Fr-TCoV 080385d) was isolated in France from turkey poults exhibiting clinical signs compatible with this syndrome. In the present study, the median infectious dose (ID ) transmission kinetics and pathogenicity of Fr-TCoV were investigated in 10-day-old SPF turkeys. Results revealed a titre of 10 ID /ml with 1 ID /ml being beyond the limit of genome detection using a well-characterized qRT-PCR for avian coronaviruses. Horizontal transmission of the virus via the airborne route was not observed however, via the oro-faecal route this proved to be extremely rapid (one infectious individual infecting another every 2.5 hr) and infectious virus was excreted for at least 6 weeks in several birds. Histological examination of different zones of the intestinal tract of the Fr-TCoV-infected turkeys showed that the virus had a preference for the lower part of t...
Swine influenza viruses (swIAVs) are known to persist endemically in farrow-to-finish pig farms, ... more Swine influenza viruses (swIAVs) are known to persist endemically in farrow-to-finish pig farms, leading to repeated swine flu outbreaks in successive batches of pigs at a similar age (mostly around 8 weeks of age). This persistence in European swine herds involves swIAVs from European lineages including H1N1, H1N2, H3N2, the 2009 H1N1 pandemic virus and their reassortants. The specific population dynamics of farrow-to-finish pig farms, the immune status of the animals at infection-time, the co-circulation of distinct subtypes leading to consecutive or concomitant infections have been evidenced as factors favouring swIAV persistence within herds. We developed a stochastic metapopulation model representing the co-circulation of two distinct swIAVs within a typical farrow-to-finish pig herd to evaluate the risk of reassortant viruses generation due to co-infection events. Control strategies related to herd management and/or vaccination schemes (batch-to-batch or mass vaccination of th...
Pathogen spread between farms results from interaction between the epidemiological characteristic... more Pathogen spread between farms results from interaction between the epidemiological characteristics of infectious agents, such as transmission route, and the contact structure between holdings. The objective of our study was to design network models of pig movements matching with epidemiological features of pathogens. Our first model represents the transmission of infectious diseases between farms only through the introduction of animals to holdings (Animal Introduction Model AIM), whereas the second one also accounts for pathogen spread through intermediate transit of trucks through farms even without any animal unloading (i.e. indirect transmission-Transit Model TM). To take the pyramidal organisation of pig production into consideration, these networks were studied at three different scales: the whole network and two subnetworks containing only breeding or production farms. The two models were applied to pig movement data recorded in France from June 2012 to December 2014. For eac...
The outputs of epidemiological models are strongly related to the structure of the model and inpu... more The outputs of epidemiological models are strongly related to the structure of the model and input parameters. The latter are defined by fitting theoretical concepts to actual data derived from field or experimental studies. However, some parameters may remain difficult to estimate and are subject to uncertainty or sensitivity analyses to determine their variation range and their global impact on model outcomes. As such, the evaluation of immunity duration is often a puzzling issue requiring long-term follow-up data that are, most of time, not available. The present analysis aims at characterizing the kinetics of antibodies against Porcine Reproductive and Respiratory Syndrome virus (PRRSv) from longitudinal data sets. The first data set consisted in the serological follow-up of 22 vaccinated gilts during 21 weeks post-vaccination (PV). The second one gathered the maternally derived antibodies (MDAs) kinetics in piglets from three different farms up to 14 weeks of age. The peak of t...
Maternally-derived antibodies (MDA) reduce piglet susceptibility to swine influenza A virus, but ... more Maternally-derived antibodies (MDA) reduce piglet susceptibility to swine influenza A virus, but interfere with post-infectious immune responses, raising questions about protection after waning of passive immunity. We therefore analysed the impact of different levels of residual MDA on virus excretion and immune responses in piglets born to vaccinated sows (MDA+) and infected with H1N1 at 5, 7 or 11 weeks of age, in comparison to piglets born to unvaccinated sows (MDA-). Subsequent protection against a second homologous infection occurring 4 weeks after the primo-infection was also investigated. MDA- pigs showed clinical signs, shed the virus, and developed specific immune responses despite some age-dependent differences: 7-week-old pigs were less affected clinically, showed a 2-day delayed excretion peak and excreted less virus than younger pigs. In MDA+ animals, clinical signs increased together with the decrease of MDA levels related to the age at infection-time. Virus shedding w...
In 2013, PED emerged for the first time in the United States (US). The porcine epidemic diarrhea ... more In 2013, PED emerged for the first time in the United States (US). The porcine epidemic diarrhea virus (PEDV) spread quickly throughout North America. Infection with PEDV causes watery diarrhea and up to 100% mortality in piglets, particularly for highly pathogenic non-InDel strains circulating in the US. PEDV is mainly transmitted by the fecal-oral route. Transmission via the venereal route has been suspected but not previously investigated. The aim of the study was to determine if PEDV could be detected in semen from infected specific pathogen-free (SPF) boars inoculated with a PEDV US non-InDel strain suggesting venereal transmission may occur. Two boars orally inoculated with PEDV showed clinical signs and virus shedding in feces. Transient presence of the PEDV genome was detected by RT-qPCR in the seminal (5.06 × 102 to 2.44 × 103 genomic copies/mL) and sperm-rich fraction of semen (5.64 × 102 to 3.40 × 104 genomic copies/mL) and a longer duration of viral shedding was observed...
The aims of this study were to assess the feasibility of individual and pen-based oral fluid samp... more The aims of this study were to assess the feasibility of individual and pen-based oral fluid sampling (OFS) in 35 pig herds with group-housed sows, compare these methods to blood sampling, and assess the factors influencing the success of sampling. Individual samples were collected from at least 30 sows per herd. Pen-based OFS was performed using devices placed in at least three pens for 45min. Information related to the farm, the sows, and their living conditions were collected. Factors significantly associated with the duration of sampling and the chewing behaviour of sows were identified by logistic regression. Individual OFS took 2min 42s on average; the type of floor, swab size, and operator were associated with a sampling time >2min. Pen-based OFS was obtained from 112 devices (62.2%). The type of floor, parity, pen-level activity, and type of feeding were associated with chewing behaviour. Pen activity was associated with the latency to interact with the device. The type of floor, gestation stage, parity, group size, and latency to interact with the device were associated with a chewing time >10min. After 15, 30 and 45min of pen-based OFS, 48%, 60% and 65% of the sows were lying down, respectively. The time spent after the beginning of sampling, genetic type, and time elapsed since the last meal were associated with 50% of the sows lying down at one time point. The mean time to blood sample the sows was 1min 16s and 2min 52s if the number of operators required was considered in the sampling time estimation. The genetic type, parity, and type of floor were significantly associated with a sampling time higher than 1min 30s. This study shows that individual OFS is easy to perform in group-housed sows by a single operator, even though straw-bedded animals take longer to sample than animals housed on slatted floors, and suggests some guidelines to optimise pen-based OFS success.
Vaccine efficacy has often been studied from the viewpoint of individual direct clinical protecti... more Vaccine efficacy has often been studied from the viewpoint of individual direct clinical protection. For several vaccines, a decrease in pathogen shedding in vaccinated animals has also been documented, which suggests that transmission between individuals has the potential to be reduced. In addition, vaccination induces an immune response in the host potentially decreasing susceptibility to infection in comparison with immunologically naïve animals. As a collective result of individual vaccinations, vaccine programmes generally have a wider impact on pathogen diffusion at the population scale. Beyond the individual protection conferred by mass vaccination campaigns, the indirect protection of non-immune individuals in contact with vaccinated ones also contributes to controlling pathogen spread at the population scale; a phenomenon known as herd immunity. Pathogen spread within pig populations is strongly related to the required vaccine coverage at the population level and to pathoge...
Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans, an emerging zoonosis mai... more Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans, an emerging zoonosis mainly transmitted via food in developed countries and for which domestic pigs are recognised as the main reservoir. It therefore appears important to understand the features and drivers of HEV infection dynamics on pig farms in order to implement HEV surveillance programmes and to assess and manage public health risks. The authors have reviewed the international scientific literature on the epidemiological characteristics of HEV in swine populations. Although prevalence estimates differed greatly from one study to another, all consistently reported high variability between farms, suggesting the existence of multifactorial conditions related to infection and within-farm transmission of the virus. Longitudinal studies and experimental trials have provided estimates of epidemiological parameters governing the transmission process (e.g. age at infection, transmission parameters, shedding perio...
La Peste Porcine Africaine (PPA) est une maladie infectieuse émergente des suidés domestiques et ... more La Peste Porcine Africaine (PPA) est une maladie infectieuse émergente des suidés domestiques et sauvages. Cette maladie contagieuse entre suidés, non transmissible à l’Homme, est à l’origine d’un syndrome hémorragique souvent fatal chez les porcs domestiques et les sangliers. L'épizootie qui sévit actuellement en Europe et en Asie a débuté en Géorgie en 2007. La souche virale impliquée, très virulente, appartenant au génotype II, est très résistante dans les viandes et l’environnement. Toutes les souches isolées en Europe comme en Asie dérivent d’une même introduction, même si le virus a évolué vers des formes moins virulentes dans certaines populations de sangliers très localisées. Depuis la Géorgie, le virus s'est propagé dans tout le Caucase et la Fédération de Russie, puis en Ukraine et en Biélorussie en 2013. En janvier 2014, la PPA a atteint les frontières orientales de l'Union européenne et s’est propagée dans les trois États baltes et en Pologne très largement d...
In order to assess influenza D virus (IDV) infections in swine in France, reference reagents were... more In order to assess influenza D virus (IDV) infections in swine in France, reference reagents were produced in specific pathogen free pigs to ensure serological and virological analyses. Hemagglutination inhibition (HI) assays were carried out on 2090 domestic pig sera collected in 2012–2018 in 102 farms. Only 31 sera from breeding sows sampled in 2014–2015 in six farrow-to-finish herds with respiratory disorders contained IDV-specific antibodies. In two of them, within-herd percentage of positive samples (73.3% and 13.3%, respectively) and HI titers (20–160) suggested IDV infections, but virus persistence was not confirmed following new sampling in 2017. All growing pigs tested seronegative, whatever their age and the sampling year. Moreover, PB1-gene RT-qPCR performed on 452 nasal swabs taken in 2015–2018 on pigs with acute respiratory syndrome (137 farms) gave negative results. In Corse, a Mediterranean island where pigs are mainly bred free-range, 2.3% of sera (n = 177) sampled o...
In Europe, modified live vaccines (MLV) are commonly used to control porcine reproductive and res... more In Europe, modified live vaccines (MLV) are commonly used to control porcine reproductive and respiratory syndrome virus (PRRSV) infection. However, they have been associated with safety issues such as reversion to virulence induced by mutation and/or recombination. On a French pig farm, we identified a field recombinant strain derived from two PRRSV-1 MLV (MLV1). As a result, we aimed to evaluate its clinical, virological, and transmission parameters in comparison with both parental strains. Three groups with six pigs in each were inoculated with either one of the two MLV1s or with the recombinant strain; six contact pigs were then added into each inoculated group. The animals were monitored daily for 35 days post-inoculation (dpi) for clinical symptoms; blood samples and nasal swabs were collected twice a week. PRRS viral load in inoculated pigs of recombinant group was higher in serum, nasal swabs, and tonsils in comparison with both vaccine groups. The first viremic contact pig ...
Hepatitis E virus (HEV) is an emerging zoonotic pathogen mainly transmitted via food in developed... more Hepatitis E virus (HEV) is an emerging zoonotic pathogen mainly transmitted via food in developed countries, and for which domestic pigs are recognised as the main reservoir. To implement an efficient HEV surveillance and control plan in the pig production sector, it is first necessary to assess the level of knowledge of pig-farming main actors about this pathogen. To this aim, an online survey was conducted between September and October 2017 to evaluate pig farmers' and veterinarians' knowledge about HEV epidemiology and its zoonotic potential. The questionnaire was filled in by 383 pig farmers and 46 pig veterinarians. Of this population, 77.8% of farmers and 8.7% of veterinarians had never heard of HEV. Our results highlight knowledge gaps among responding farmers, especially regarding the clinical and epidemiological features of HEV, while veterinarians appear to be well-informed about this pathogen. These findings indicate significant room for further improvement and th...
Corsica is a mountainous French island in the north-western Mediterranean Sea. It is a rural area... more Corsica is a mountainous French island in the north-western Mediterranean Sea. It is a rural area, where pig farming is a major economic activity. Although no acute respiratory outbreaks due to swine influenza A viruses (swIAVs) have ever been reported in this free-ranging pig breeding system, influenza A viruses (IAVs) could be circulating within this pig population. A serological study was conducted as a first approach to domestic pigs and wild boars. Serum samples from 543 pigs raised on 91 different farms were collected during the 2013-2014 slaughtering season, and 279 sera from wild boars were obtained over four hunting seasons (between 2009 and 2014). They were first analysed by ELISA and then IAV positive and doubtful sera were subjected to haemagglutination inhibition tests using antigens representative of the four major enzootic swIAV lineages in Europe, i.e. avian-like swine H1N1 (H1N1), pandemic-like swine H1N1 (H1N1pdm), H1N2 and H3N2. According to the ELISA results, 26....
Numerous viruses, mostly in mixed infections, have been associated worldwide with poult enteritis... more Numerous viruses, mostly in mixed infections, have been associated worldwide with poult enteritis complex (PEC). In 2008 a coronavirus (Fr-TCoV 080385d) was isolated in France from turkey poults exhibiting clinical signs compatible with this syndrome. In the present study, the median infectious dose (ID ) transmission kinetics and pathogenicity of Fr-TCoV were investigated in 10-day-old SPF turkeys. Results revealed a titre of 10 ID /ml with 1 ID /ml being beyond the limit of genome detection using a well-characterized qRT-PCR for avian coronaviruses. Horizontal transmission of the virus via the airborne route was not observed however, via the oro-faecal route this proved to be extremely rapid (one infectious individual infecting another every 2.5 hr) and infectious virus was excreted for at least 6 weeks in several birds. Histological examination of different zones of the intestinal tract of the Fr-TCoV-infected turkeys showed that the virus had a preference for the lower part of t...
Swine influenza viruses (swIAVs) are known to persist endemically in farrow-to-finish pig farms, ... more Swine influenza viruses (swIAVs) are known to persist endemically in farrow-to-finish pig farms, leading to repeated swine flu outbreaks in successive batches of pigs at a similar age (mostly around 8 weeks of age). This persistence in European swine herds involves swIAVs from European lineages including H1N1, H1N2, H3N2, the 2009 H1N1 pandemic virus and their reassortants. The specific population dynamics of farrow-to-finish pig farms, the immune status of the animals at infection-time, the co-circulation of distinct subtypes leading to consecutive or concomitant infections have been evidenced as factors favouring swIAV persistence within herds. We developed a stochastic metapopulation model representing the co-circulation of two distinct swIAVs within a typical farrow-to-finish pig herd to evaluate the risk of reassortant viruses generation due to co-infection events. Control strategies related to herd management and/or vaccination schemes (batch-to-batch or mass vaccination of th...
Pathogen spread between farms results from interaction between the epidemiological characteristic... more Pathogen spread between farms results from interaction between the epidemiological characteristics of infectious agents, such as transmission route, and the contact structure between holdings. The objective of our study was to design network models of pig movements matching with epidemiological features of pathogens. Our first model represents the transmission of infectious diseases between farms only through the introduction of animals to holdings (Animal Introduction Model AIM), whereas the second one also accounts for pathogen spread through intermediate transit of trucks through farms even without any animal unloading (i.e. indirect transmission-Transit Model TM). To take the pyramidal organisation of pig production into consideration, these networks were studied at three different scales: the whole network and two subnetworks containing only breeding or production farms. The two models were applied to pig movement data recorded in France from June 2012 to December 2014. For eac...
The outputs of epidemiological models are strongly related to the structure of the model and inpu... more The outputs of epidemiological models are strongly related to the structure of the model and input parameters. The latter are defined by fitting theoretical concepts to actual data derived from field or experimental studies. However, some parameters may remain difficult to estimate and are subject to uncertainty or sensitivity analyses to determine their variation range and their global impact on model outcomes. As such, the evaluation of immunity duration is often a puzzling issue requiring long-term follow-up data that are, most of time, not available. The present analysis aims at characterizing the kinetics of antibodies against Porcine Reproductive and Respiratory Syndrome virus (PRRSv) from longitudinal data sets. The first data set consisted in the serological follow-up of 22 vaccinated gilts during 21 weeks post-vaccination (PV). The second one gathered the maternally derived antibodies (MDAs) kinetics in piglets from three different farms up to 14 weeks of age. The peak of t...
Maternally-derived antibodies (MDA) reduce piglet susceptibility to swine influenza A virus, but ... more Maternally-derived antibodies (MDA) reduce piglet susceptibility to swine influenza A virus, but interfere with post-infectious immune responses, raising questions about protection after waning of passive immunity. We therefore analysed the impact of different levels of residual MDA on virus excretion and immune responses in piglets born to vaccinated sows (MDA+) and infected with H1N1 at 5, 7 or 11 weeks of age, in comparison to piglets born to unvaccinated sows (MDA-). Subsequent protection against a second homologous infection occurring 4 weeks after the primo-infection was also investigated. MDA- pigs showed clinical signs, shed the virus, and developed specific immune responses despite some age-dependent differences: 7-week-old pigs were less affected clinically, showed a 2-day delayed excretion peak and excreted less virus than younger pigs. In MDA+ animals, clinical signs increased together with the decrease of MDA levels related to the age at infection-time. Virus shedding w...
In 2013, PED emerged for the first time in the United States (US). The porcine epidemic diarrhea ... more In 2013, PED emerged for the first time in the United States (US). The porcine epidemic diarrhea virus (PEDV) spread quickly throughout North America. Infection with PEDV causes watery diarrhea and up to 100% mortality in piglets, particularly for highly pathogenic non-InDel strains circulating in the US. PEDV is mainly transmitted by the fecal-oral route. Transmission via the venereal route has been suspected but not previously investigated. The aim of the study was to determine if PEDV could be detected in semen from infected specific pathogen-free (SPF) boars inoculated with a PEDV US non-InDel strain suggesting venereal transmission may occur. Two boars orally inoculated with PEDV showed clinical signs and virus shedding in feces. Transient presence of the PEDV genome was detected by RT-qPCR in the seminal (5.06 × 102 to 2.44 × 103 genomic copies/mL) and sperm-rich fraction of semen (5.64 × 102 to 3.40 × 104 genomic copies/mL) and a longer duration of viral shedding was observed...
The aims of this study were to assess the feasibility of individual and pen-based oral fluid samp... more The aims of this study were to assess the feasibility of individual and pen-based oral fluid sampling (OFS) in 35 pig herds with group-housed sows, compare these methods to blood sampling, and assess the factors influencing the success of sampling. Individual samples were collected from at least 30 sows per herd. Pen-based OFS was performed using devices placed in at least three pens for 45min. Information related to the farm, the sows, and their living conditions were collected. Factors significantly associated with the duration of sampling and the chewing behaviour of sows were identified by logistic regression. Individual OFS took 2min 42s on average; the type of floor, swab size, and operator were associated with a sampling time >2min. Pen-based OFS was obtained from 112 devices (62.2%). The type of floor, parity, pen-level activity, and type of feeding were associated with chewing behaviour. Pen activity was associated with the latency to interact with the device. The type of floor, gestation stage, parity, group size, and latency to interact with the device were associated with a chewing time >10min. After 15, 30 and 45min of pen-based OFS, 48%, 60% and 65% of the sows were lying down, respectively. The time spent after the beginning of sampling, genetic type, and time elapsed since the last meal were associated with 50% of the sows lying down at one time point. The mean time to blood sample the sows was 1min 16s and 2min 52s if the number of operators required was considered in the sampling time estimation. The genetic type, parity, and type of floor were significantly associated with a sampling time higher than 1min 30s. This study shows that individual OFS is easy to perform in group-housed sows by a single operator, even though straw-bedded animals take longer to sample than animals housed on slatted floors, and suggests some guidelines to optimise pen-based OFS success.
Vaccine efficacy has often been studied from the viewpoint of individual direct clinical protecti... more Vaccine efficacy has often been studied from the viewpoint of individual direct clinical protection. For several vaccines, a decrease in pathogen shedding in vaccinated animals has also been documented, which suggests that transmission between individuals has the potential to be reduced. In addition, vaccination induces an immune response in the host potentially decreasing susceptibility to infection in comparison with immunologically naïve animals. As a collective result of individual vaccinations, vaccine programmes generally have a wider impact on pathogen diffusion at the population scale. Beyond the individual protection conferred by mass vaccination campaigns, the indirect protection of non-immune individuals in contact with vaccinated ones also contributes to controlling pathogen spread at the population scale; a phenomenon known as herd immunity. Pathogen spread within pig populations is strongly related to the required vaccine coverage at the population level and to pathoge...
Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans, an emerging zoonosis mai... more Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans, an emerging zoonosis mainly transmitted via food in developed countries and for which domestic pigs are recognised as the main reservoir. It therefore appears important to understand the features and drivers of HEV infection dynamics on pig farms in order to implement HEV surveillance programmes and to assess and manage public health risks. The authors have reviewed the international scientific literature on the epidemiological characteristics of HEV in swine populations. Although prevalence estimates differed greatly from one study to another, all consistently reported high variability between farms, suggesting the existence of multifactorial conditions related to infection and within-farm transmission of the virus. Longitudinal studies and experimental trials have provided estimates of epidemiological parameters governing the transmission process (e.g. age at infection, transmission parameters, shedding perio...
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Papers by Nicolas Rose