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Benavides B, Monti G. Bovine leukemia virus transmission rates in persistent lymphocytotic infected dairy cows. Front Vet Sci 2024; 11:1367810. [PMID: 39086766 PMCID: PMC11288960 DOI: 10.3389/fvets.2024.1367810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 07/08/2024] [Indexed: 08/02/2024] Open
Abstract
Bovine leukemia virus (BLV) establishes a lifelong persistent infection in dairy cattle. White blood cell count (WBC) is correlated with proviral load in the blood and milk of BLV-infected cattle, and testing WBC can be used to assess both BLV infectiousness levels and risk of BLV transmission from different types of infected animals. The objective of the study was to compare effective transmission rates (β) and the basic reproduction ratio (R o) among two types of BLV-infected dairy cows in Chile: those affected with persistent lymphocytosis (PL) vs. aleukemic (AL).The estimated (β) coefficient was higher in PL cattle [1.1; 95% Confidence interval (CI) (-1.6, 3.8)], compared to AL cattle (-3.1; 95% CI = -3.7, -2.5). In addition, the R o was higher in PL cattle (60.4; 95% CI = 3.5; 820.6), compared to AL cattle (1.5; 95% CI = 0.7, 3.1). The ratio between PL/AL expected rate of cases was 73.9. The estimated effective transmission rate and the Ro were higher in PL cattle compared to AL cattle. The WBC test is a convenient alternative that can be considered for risk identification and risk management of BLV infection in dairy herds; particularly in livestock regions where laboratory capacity is limited (e.g., use of PCR or gene sequencing techniques) and/or molecular tests are not cost-effective. Therefore, when prevalence of infection is high, the removal of PL cattle should be engaged to control BLV within-herds.
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Affiliation(s)
- Bibiana Benavides
- Animal Health Department, University of Nariño, San Juan de Pasto, Colombia
| | - Gustavo Monti
- Quantitative Veterinary Epidemiology Group, Wageningen University, Wageningen, Netherlands
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2
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Fromsa A, Willgert K, Srinivasan S, Mekonnen G, Bedada W, Gumi B, Lakew M, Tadesse B, Bayissa B, Sirak A, Girma Abdela M, Gebre S, Chibssa T, Veerasami M, Vordermeier HM, Bakker D, Berg S, Ameni G, Juleff N, de Jong MCM, Wood J, Conlan A, Kapur V. BCG vaccination reduces bovine tuberculosis transmission, improving prospects for elimination. Science 2024; 383:eadl3962. [PMID: 38547287 DOI: 10.1126/science.adl3962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 01/24/2024] [Indexed: 04/02/2024]
Abstract
Bacillus Calmette-Guérin (BCG) is a routinely used vaccine for protecting children against Mycobacterium tuberculosis that comprises attenuated Mycobacterium bovis. BCG can also be used to protect livestock against M. bovis; however, its effectiveness has not been quantified for this use. We performed a natural transmission experiment to directly estimate the rate of transmission to and from vaccinated and unvaccinated calves over a 1-year exposure period. The results show a higher indirect efficacy of BCG to reduce transmission from vaccinated animals that subsequently become infected [74%; 95% credible interval (CrI): 46 to 98%] compared with direct protection against infection (58%; 95% CrI: 34 to 73%) and an estimated total efficacy of 89% (95% CrI: 74 to 96%). A mechanistic transmission model of bovine tuberculosis (bTB) spread within the Ethiopian dairy sector was developed and showed how the prospects for elimination may be enabled by routine BCG vaccination of cattle.
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Affiliation(s)
- Abebe Fromsa
- Aklilu Lemma Institutes of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
- College of Veterinary Medicine and Agriculture, Addis Ababa University, Bishoftu, Ethiopia
| | - Katriina Willgert
- Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, UK
| | - Sreenidhi Srinivasan
- Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA, USA
- Department of Animal Science, The Pennsylvania State University, University Park, PA, USA
- The Global Health Initiative, Henry Ford Health, Detroit, MI, USA
| | | | | | - Balako Gumi
- Aklilu Lemma Institutes of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | | | | | - Berecha Bayissa
- Aklilu Lemma Institutes of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | | | - Musse Girma Abdela
- Aklilu Lemma Institutes of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | | | | | | | | | - Douwe Bakker
- Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA, USA
- Technical Consultant and Independent Researcher, Lelystad, Netherlands
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain
| | - Stefan Berg
- Animal and Plant Health Agency, Weybridge, UK
| | - Gobena Ameni
- Aklilu Lemma Institutes of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
- Department of Veterinary Medicine, College of Agriculture and Veterinary Medicine, United Arab Emirates University, United Arab Emirates
| | - Nick Juleff
- The Bill & Melinda Gates Foundation Seattle, WA, USA
| | - Mart C M de Jong
- Quantitative Veterinary Epidemiology Group, Wageningen UR, The Netherlands
| | - James Wood
- Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, UK
| | - Andrew Conlan
- Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, UK
| | - Vivek Kapur
- Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA, USA
- Department of Animal Science, The Pennsylvania State University, University Park, PA, USA
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3
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Tadesse B, Aregahagn S, Muluneh BT, Worku Y. Spatio-temporal ditribution and transmission dynamics of sheep pox and goat pox diseases in South Wollo zone north East Ethiopia. Heliyon 2024; 10:e27470. [PMID: 38486769 PMCID: PMC10937688 DOI: 10.1016/j.heliyon.2024.e27470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 02/20/2024] [Accepted: 02/29/2024] [Indexed: 03/17/2024] Open
Abstract
Sheep pox (SP) and goat pox diseases (GP) are highly transmittable, malignant systemic and economically significant caused by the genus Capripoxvirus. using The spatio-temporal distribution of SP and GP outbreaks in South Wollo zone from September 2013 to December 2019 was determined retrospectively using SP and GP outbreaks report Kombolcha regional laboratory. A follow up study was also conducted from December 2019 to March 2021 to estimate the transmission parameter of SP and GP outbreaks in South Wollo zone of Kutaber district, Amhara region. Tissue samples from outbreaks in Kundi and Haroye kebele of Kutaber district were taken to confirm the outbreak by conventional polymerase chain reaction (PCR). The transmission parameters were estimated using Generalized linear model (GLM) based on stochastic Susceptible Infected and Recovered (SIR) model. In South Wollo zone, 249 SGP outbreaks were reported from 2013 to 2019. The incidence differed between months, with a highest peak in October and November and a lowest peak in February. The basic reproduction ratios (R0) of the SGP disease outbreaks were 1.84 and 3 for Haroye and Kundi kebele outbreaks, respectively. The disease is distributed throughout the zone and the investigated active outbreaks had moderate transmission between animals. Hence, it needs a great effort which focuses on the application of control measures that reduce the transmission of the disease.
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Affiliation(s)
- Belege Tadesse
- Wollo University, School of Veterinary Medicine, P.O. Box. 1145, Dessie, Ethiopia
| | - Sileshi Aregahagn
- Wollo University, School of Veterinary Medicine, P.O. Box. 1145, Dessie, Ethiopia
- Kombolcha College of Agriculture Affliated to Wollo University, Kombolcha, Ethiopia
| | - Bethelihem Tegegne Muluneh
- Department of Veterinary Laboratory Technology, College of Agriculture, Food and Climate Science, Injibara University, Injibara, Ethiopia
| | - Yalelet Worku
- Wollo University, School of Veterinary Medicine, P.O. Box. 1145, Dessie, Ethiopia
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4
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Hulst AD, Bijma P, De Jong MCM. Can breeders prevent pathogen adaptation when selecting for increased resistance to infectious diseases? GENETICS SELECTION EVOLUTION 2022; 54:73. [DOI: 10.1186/s12711-022-00764-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 10/24/2022] [Indexed: 11/09/2022]
Abstract
Abstract
Background
Recent research shows that genetic selection has high potential to reduce the prevalence of infectious diseases in livestock. However, like all interventions that target infectious diseases, genetic selection of livestock can exert selection pressure on pathogen populations. Such selection on the pathogen may lead to escape strategies and reduce the effect of selection of livestock for disease resistance. Thus, to successfully breed livestock for lower disease prevalence, it is essential to develop strategies that prevent the invasion of pathogen mutants that escape host resistance. Here we investigate the conditions under which such “escape mutants” can replace wild-type pathogens in a closed livestock population using a mathematical model of disease transmission.
Results
Assuming a single gene that confers sufficient resistance, results show that genetic selection for resistance in livestock typically leads to an “invasion window” within which an escape mutant of the pathogen can invade. The bounds of the invasion window are determined by the frequency of resistant hosts in the population. The lower bound occurs when the escape mutant has an advantage over the wild-type pathogen in the population. The upper bound occurs when local eradication of the pathogen is expected. The invasion window is smallest when host resistance is strong and when infection with the wild-type pathogen provides cross immunity to infection with the escape mutant.
Conclusions
To minimise opportunities for pathogens to adapt, under the assumptions of our model, the aim of disease control through genetic selection should be to achieve herd-level eradication of the infection faster than the rate of emergence of escape mutants of the pathogen. Especially for microparasitic infections, this could be achieved by placing animals into herds according to their genetic resistance, such that these herds stay completely out of the invasion window. In contrast to classical breeding theory, our model suggests that multi-trait selection with gradual improvement of each trait of the breeding goal might not be the best strategy when resistance to infectious disease is part of the breeding goal. Temporally, combining genetic selection with other interventions helps to make the invasion window smaller, and thereby reduces the risk of invasion of escape mutants.
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Stringer OW, Li Y, Bossé JT, Forrest MS, Hernandez-Garcia J, Tucker AW, Nunes T, Costa F, Mortensen P, Velazquez E, Penny P, Rodriguez-Manzano J, Georgiou P, Langford PR. Rapid Detection of Actinobacillus pleuropneumoniae From Clinical Samples Using Recombinase Polymerase Amplification. Front Vet Sci 2022; 9:805382. [PMID: 35400111 PMCID: PMC8990124 DOI: 10.3389/fvets.2022.805382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 02/25/2022] [Indexed: 11/30/2022] Open
Abstract
Actinobacillus pleuropneumoniae (APP) is the causative agent of porcine pleuropneumonia, resulting in high economic impact worldwide. There are currently 19 known serovars of APP, with different ones being predominant in specific geographic regions. Outbreaks of pleuropneumonia, characterized by sudden respiratory difficulties and high mortality, can occur when infected pigs are brought into naïve herds, or by those carrying different serovars. Good biosecurity measures include regular diagnostic testing for surveillance purposes. Current gold standard diagnostic techniques lack sensitivity (bacterial culture), require expensive thermocycling machinery (PCR) and are time consuming (culture and PCR). Here we describe the development of an isothermal point-of-care diagnostic test - utilizing recombinase polymerase amplification (RPA) for the detection of APP, targeting the species-specific apxIVA gene. Our APP-RPA diagnostic test achieved a sensitivity of 10 copies/μL using a strain of APP serovar 8, which is the most prevalent serovar in the UK. Additionally, our APP-RPA assay achieved a clinical sensitivity and specificity of 84.3 and 100%, respectively, across 61 extracted clinical samples obtained from farms located in England and Portugal. Using a small subset (n = 14) of the lung tissue samples, we achieved a clinical sensitivity and specificity of 76.9 and 100%, respectively) using lung imprints made on FTA cards tested directly in the APP-RPA reaction. Our results demonstrate that our APP-RPA assay enables a suitable rapid and sensitive screening tool for this important veterinary pathogen.
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Affiliation(s)
- Oliver W. Stringer
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Yanwen Li
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Janine T. Bossé
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | | | - Juan Hernandez-Garcia
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Alexander W. Tucker
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Tiago Nunes
- Ceva Animal Health Ltd., Saúde Animal, Algés, Portugal
| | | | | | | | - Paul Penny
- Ceva Animal Health Ltd., Amersham, United Kingdom
| | - Jesus Rodriguez-Manzano
- Section of Adult Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Pantelis Georgiou
- Department of Electrical and Electronic Engineering, Imperial College London, London, United Kingdom
| | - Paul R. Langford
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
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6
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Matsuyama R, Yamamoto T, Hayama Y, Omori R. Estimation of the Lethality Rate, Recovery Rate, and Case Fatality Ratio of Classical Swine Fever in Japanese Wild Boar: An Analysis of the Epidemics From September 2018 to March 2019. Front Vet Sci 2021; 8:772995. [PMID: 34977211 PMCID: PMC8714742 DOI: 10.3389/fvets.2021.772995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 11/11/2021] [Indexed: 11/13/2022] Open
Abstract
Understanding the morbidity and lethality of diseases is necessary to evaluate the effectiveness of countermeasure against the epidemics (e.g., vaccination). To estimate them, detailed data on host population dynamics are required; however, estimating the population size for wildlife is often difficult. We aimed to elucidate the morbidity and lethality of classical swine fever (CSF) currently highly prevalent in the wild boar population in Japan. To this end, we estimated lethality rate, recovery rate, and case fatality ratio (CFR) of CSF without detailed data on the population estimates of wild boar. A mathematical model was constructed to describe the CSF dynamics and population dynamics of wild boar. We fitted the model to the (i) results of the reverse transcription polymerase chain reaction (RT-PCR) test for the CSFV gene and the (ii) results of the enzyme-linked immunosorbent assay (ELISA) test for the antibody against CSFV in sampled wild boar. In the 280 wild boar sampled from September 2018 to March 2019 in the major CSF-affected area in Japan, the lethality rate and recovery rate of CSF per week were estimated as 0.165 (95% confidence interval: 0.081–0.250) and 0.004 (0–0.009), respectively. While the estimate of lethality rate of CSF was similar with the estimates in previous studies, the recovery rate was lower than those reported previously. CFR was estimated as 0.959 (0.904–0.981) using our estimate of recovery rate. This study is the first to estimate lethality rate of CSF from the dynamics of CSF epidemics in the wild boar population. Since the value of CFR is sensitive to the value of recovery rate, the accuracy in the estimate of recovery rate is a key for the accurate estimation of CFR. A long-term transmission experiment of moderately virulent strains may lead to more accurate estimation of the recovery rate and CFR of CSF.
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Affiliation(s)
- Ryota Matsuyama
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Takehisa Yamamoto
- Epidemiology Research Unit, Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Yoko Hayama
- Epidemiology Research Unit, Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Ryosuke Omori
- International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
- *Correspondence: Ryosuke Omori
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Doeschl-Wilson A, Knap PW, Opriessnig T, More SJ. Review: Livestock disease resilience: from individual to herd level. Animal 2021; 15 Suppl 1:100286. [PMID: 34312089 PMCID: PMC8664713 DOI: 10.1016/j.animal.2021.100286] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/12/2021] [Accepted: 04/15/2021] [Indexed: 11/23/2022] Open
Abstract
Infectious diseases are a major threat to the sustainable production of high-producing animals. Control efforts, such as vaccination or breeding approaches often target improvements to individual resilience to infections, i.e., they strengthen an animal's ability to cope with infection, rather than preventing infection per se. There is increasing evidence for the contribution of non-clinical carriers (animals that become infected and are infectious but do not develop clinical signs) to the overall health and production of livestock populations for a wide range of infectious diseases. Therefore, we strongly advocate a shift of focus from increasing the disease resilience of individual animals to herd disease resilience as the appropriate target for sustainable disease control in livestock. Herd disease resilience not only captures the direct effects of vaccination or host genetics on the health and production performance of individuals but also the indirect effects on the environmental pathogen load that herd members are exposed to. For diseases primarily caused by infectious pathogens shed by herd members, these indirect effects on herd resilience are mediated both by individual susceptibility to infection and by characteristics (magnitude of infectiousness, duration of infectious period) that influence pathogen shedding from infected individuals. We review what is currently known about how vaccination and selective breeding affect herd disease resilience and its underlying components, and outline the changes required for improvement. To this purpose, we also seek to clarify and harmonise the terminology used in the different animal science disciplines to facilitate future collaborative approaches to infectious disease control in livestock.
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Affiliation(s)
- A Doeschl-Wilson
- The Roslin Institute, University of Edinburgh, Roslin Institute Building, Easter Bush EH25 9RG, Scotland, UK.
| | - P W Knap
- Genus-PIC, 24837 Schleswig, Germany
| | - T Opriessnig
- The Roslin Institute, University of Edinburgh, Roslin Institute Building, Easter Bush EH25 9RG, Scotland, UK
| | - S J More
- Centre for Veterinary Epidemiology and Risk Analysis, School of Veterinary Medicine, University College Dublin, Veterinary Science Centre Belfield, Dublin D04 W6F6, Ireland
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8
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Cohen LM, Bossé JT, Stegger M, Li Y, Langford PR, Kielland C, Klem TB, Gulliksen SM, Ranheim B, Grøntvedt CA, Angen Ø. Comparative Genome Sequence Analysis of Actinobacillus pleuropneumoniae Serovar 8 Isolates From Norway, Denmark, and the United Kingdom Indicates Distinct Phylogenetic Lineages and Differences in Distribution of Antimicrobial Resistance Genes. Front Microbiol 2021; 12:729637. [PMID: 34566934 PMCID: PMC8461171 DOI: 10.3389/fmicb.2021.729637] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 08/13/2021] [Indexed: 11/13/2022] Open
Abstract
Actinobacillus pleuropneumoniae is the etiological agent of porcine pleuropneumonia, a disease of major impact on pig health, welfare, and productivity globally. Serovar 8 (APP) is the predominant clinical serovar in Norway and the United Kingdom (UK), and has been isolated from clinical cases in Denmark. The primary objective of this study was to characterize the genetic variability of isolates of A. pleuropneumoniae APP8 in the Norwegian population. The secondary objectives were to determine the within-host variability of APP8; to compare the APP8 bacterial populations in Norway, Denmark, and the UK, including antimicrobial resistance (AMR) gene profiles and to assess the effect of national differences in antimicrobial drug use and restricted animal movement on the occurrence of resistance. Isolates of APP8 from the UK (n=67), Denmark (n=22), and Norway (n=123) collected between 1983 and 2020 were compared using whole genome sequencing. To investigate genetic variability within individual hosts, an additional 104 APP8 isolates from the lungs of six Norwegian pigs were compared. Very low within-host variation was observed (≤ 2 single nucleotide polymorphisms). The phylogeny of 123 Norwegian APP8 isolates from 76 herds revealed some within-herd genetic variation, but substantial geographical clustering. When inferring the relatedness of the three international APP8 collections, the topology highlighted the existence of two distinct monophyletic branches characterized by the Norwegian and UK isolates, respectively. Three Danish isolates were scattered across the UK branch, whereas the remaining 19 Danish isolates clustered in two monophyletic groups nested in the Norwegian branch. Coalescence analysis, performed to estimate the divergences from a common ancestor, indicated a last common ancestor several centuries ago. The phylogenetic analyses also revealed striking differences in occurrence of AMR genes, as these were 23-times more prevalent among the UK isolates than among the Norwegian isolates. An increased understanding of the effects of population strategies is helpful in surveillance and control of infectious diseases.
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Affiliation(s)
- Liza Miriam Cohen
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Oslo, Norway
| | - Janine T Bossé
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Marc Stegger
- Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark
| | - Yanwen Li
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Paul R Langford
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Camilla Kielland
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Oslo, Norway
| | | | | | - Birgit Ranheim
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Oslo, Norway
| | | | - Øystein Angen
- Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark
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9
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Natural transmission and detection of Mycoplasma hyopneumoniae in a naïve gilt population. Vet Microbiol 2020; 248:108819. [PMID: 32891949 DOI: 10.1016/j.vetmic.2020.108819] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 08/01/2020] [Indexed: 11/21/2022]
Abstract
Mycoplasma hyopneumoniae (M. hyopneumoniae) continues to be a prevalent and economically important swine respiratory pathogen. For M. hyopneumoniae surveillance, blood samples and/or oral fluids are commonly collected from incoming replacement gilts prior to entering sow farms. However, limitations to this approach exist, particularly due to low sensitivity during acute stages of natural infection, leading to diagnostic uncertainty. Therefore, the objective of this study was to evaluate the natural transmission and detection of M. hyopneumoniae based on the introduction of one infected gilt to a naïve population. Twenty-nine naïve gilts were housed with one M. hyopneumoniae naturally exposed gilt for 8 weeks. Deep tracheal catheters, laryngeal swabs, and blood samples were individually collected from each gilt at 0, 1, 2, 4, 6, and 8 weeks post-contact (wpc), along with one pen-based oral fluid sample. Blood samples were assayed by ELISA, while all other samples were tested by real-time PCR. The transmission rate of M. hyopneumoniae (ꞵ) was estimated using a Bayesian mixed-effects generalized linear model. At 8 wpc, 27 % (8/29) of the naïve gilts had become infected (ꞵ = 0.73 new infected gilts/gilt-week). Seroconversion was detected in 3% of contact gilts at 8 wpc. Oral fluids were negative for M. hyopneumoniae at all samplings. In this study, the natural transmission of M. hyopneumoniae was slow and detection varied based on sample type and timing. Thus, M. hyopneumoniae surveillance protocols should include lower respiratory tract samples that are tested by real-time PCR to avoid the introduction of potentially infected gilts into naïve sow farms.
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10
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Bailey RI, Cheng HH, Chase-Topping M, Mays JK, Anacleto O, Dunn JR, Doeschl-Wilson A. Pathogen transmission from vaccinated hosts can cause dose-dependent reduction in virulence. PLoS Biol 2020; 18:e3000619. [PMID: 32134914 PMCID: PMC7058279 DOI: 10.1371/journal.pbio.3000619] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 01/30/2020] [Indexed: 02/07/2023] Open
Abstract
Many livestock and human vaccines are leaky because they block symptoms but do not prevent infection or onward transmission. This leakiness is concerning because it increases vaccination coverage required to prevent disease spread and can promote evolution of increased pathogen virulence. Despite leakiness, vaccination may reduce pathogen load, affecting disease transmission dynamics. However, the impacts on post-transmission disease development and infectiousness in contact individuals are unknown. Here, we use transmission experiments involving Marek disease virus (MDV) in chickens to show that vaccination with a leaky vaccine substantially reduces viral load in both vaccinated individuals and unvaccinated contact individuals they infect. Consequently, contact birds are less likely to develop disease symptoms or die, show less severe symptoms, and shed less infectious virus themselves, when infected by vaccinated birds. These results highlight that even partial vaccination with a leaky vaccine can have unforeseen positive consequences in controlling the spread and symptoms of disease.
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Affiliation(s)
- Richard I. Bailey
- Division of Genetics and Genomics, The Roslin Institute, Easter Bush, Midlothian, United Kingdom
| | - Hans H. Cheng
- USDA, Agricultural Research Service, US National Poultry Research Center, Avian Disease and Oncology Laboratory, East Lansing, Michigan, United States of America
| | - Margo Chase-Topping
- Division of Genetics and Genomics, The Roslin Institute, Easter Bush, Midlothian, United Kingdom
- Usher Institute of Population Health Sciences & Informatics, University of Edinburgh, Edinburgh, United Kingdom
| | - Jody K. Mays
- USDA, Agricultural Research Service, US National Poultry Research Center, Avian Disease and Oncology Laboratory, East Lansing, Michigan, United States of America
| | - Osvaldo Anacleto
- Division of Genetics and Genomics, The Roslin Institute, Easter Bush, Midlothian, United Kingdom
| | - John R. Dunn
- USDA, Agricultural Research Service, US National Poultry Research Center, Avian Disease and Oncology Laboratory, East Lansing, Michigan, United States of America
| | - Andrea Doeschl-Wilson
- Division of Genetics and Genomics, The Roslin Institute, Easter Bush, Midlothian, United Kingdom
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11
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Xiao T, Yang Y, Zhang Y, Cheng P, Yu H, Liu R, Ishfaq M, Zhang X. Efficacy of gamithromycin injection administered intramuscularly against bacterial swine respiratory disease. Res Vet Sci 2020; 128:118-123. [PMID: 31778852 DOI: 10.1016/j.rvsc.2019.11.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 11/04/2019] [Accepted: 11/12/2019] [Indexed: 12/25/2022]
Abstract
The aim of this study is to evaluate the safety and efficacy of gamithromycin (GAM) for the treatment of naturally occurring bacterial swine respiratory disease (SRD) administered IM. A total of 240 pigs (nine-weeks old) were selected from two sites in Heilongjiang Province of China. The pigs showed severe signs of respiratory disease. Among them, 120 pigs were randomly divided into 4 groups of low dose (3 mg/kg), middle dose (6 mg/kg), high dose (12 mg/kg) GAM IM injection and 2.5 mg/kg tulathromycin (TUL) IM injection (positive control group) for phase II clinical trial to screen effective therapeutic dose. The other 120 pigs were randomly divided into 2 groups of 6 mg/kg GAM IM injection and 2.5 mg/kg TUL IM injection (positive control group) for phase III clinical trial to further confirm the efficacy. Animals were clinically observed daily for 14 days after treatment initiation. The predominant pathogens present in pretreatment respiratory tract samples were Streptococcus suis (S. suis) and Actinobacillus pleuropneumoniae (A. pleuropneumoniae). Haemophilus parasuis (H. parasuis) and Pasteurella multocida (P. multocida) were also found in the respiratory tract. All isolates were subjected to in vitro sensitivity testing and the measured minimal inhibitory concentrations (MIC) of GAM were from 0.0625 μg/mL to 8 μg/mL. In all treatment groups, rectal temperature dropped and clinical index (mental status and respiratory symptom) significantly improved after treatment (P ≤ .05). As a result, 82.76% animals treated with the 6 mg/kg GAM injection were cured. This was significantly higher than that of 3 mg/kg GAM injection (P ≤ .05) and similar to that of 12 mg/kg GAM injection and 2.5 mg/kg TUL injection (P > .05) in phase II clinical trial. In phase III clinical trial, 80.70% of animals treated with the 6 mg/kg GAM injection were cured and the cure rate was similar to that of 2.5 mg/kg TUL injection (P > .05). In conclusion, we recommended a single dose (6 mg/kg) of GAM IM injection for the treatment of bacterial SRD.
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Affiliation(s)
- Tianshi Xiao
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Faculty of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Xiangfang District, Harbin, PR China
| | - Yuqi Yang
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Faculty of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Xiangfang District, Harbin, PR China
| | - Yixin Zhang
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Faculty of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Xiangfang District, Harbin, PR China
| | - Ping Cheng
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Faculty of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Xiangfang District, Harbin, PR China
| | - Hongxiao Yu
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Faculty of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Xiangfang District, Harbin, PR China
| | - Ruimeng Liu
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Faculty of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Xiangfang District, Harbin, PR China
| | - Muhammad Ishfaq
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Faculty of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Xiangfang District, Harbin, PR China
| | - Xiuying Zhang
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Faculty of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Xiangfang District, Harbin, PR China; Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China.
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12
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Biemans F, de Jong MCM, Bijma P. Genetic parameters and genomic breeding values for digital dermatitis in Holstein Friesian dairy cattle: host susceptibility, infectivity and the basic reproduction ratio. Genet Sel Evol 2019; 51:67. [PMID: 31747869 PMCID: PMC6865030 DOI: 10.1186/s12711-019-0505-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 10/25/2019] [Indexed: 12/19/2022] Open
Abstract
Background For infectious diseases, the probability that an animal gets infected depends on its own susceptibility, and on the number of infectious herd mates and their infectivity. Together with the duration of the infectious period, susceptibility and infectivity determine the basic reproduction ratio of the disease (\documentclass[12pt]{minimal}
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\begin{document}$$ R_{0} $$\end{document}R0). \documentclass[12pt]{minimal}
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\begin{document}$$ R_{0} $$\end{document}R0 is the average number of secondary cases caused by a typical infectious individual in an otherwise uninfected population. An infectious disease dies out when \documentclass[12pt]{minimal}
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\begin{document}$$ R_{0} $$\end{document}R0 is lower than 1. Thus, breeding strategies that aim at reducing disease prevalence should focus on reducing \documentclass[12pt]{minimal}
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\begin{document}$$ R_{0} $$\end{document}R0, preferably to a value lower than 1. In animal breeding, however, \documentclass[12pt]{minimal}
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\begin{document}$$ R_{0} $$\end{document}R0 has received little attention. Here, we estimate the additive genetic variance in host susceptibility, host infectivity, and \documentclass[12pt]{minimal}
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\begin{document}$$ R_{0} $$\end{document}R0 for the endemic claw disease digital dermatitis (DD) in Holstein Friesian dairy cattle, and estimate genomic breeding values (GEBV) for these traits. We recorded DD disease status of both hind claws of 1513 cows from 12 Dutch dairy farms, every 2 weeks, 11 times. The genotype data consisted of 75,904 single nucleotide polymorphisms (SNPs) for 1401 of the cows. We modelled the probability that a cow got infected between recordings, and compared four generalized linear mixed models. All models included a genetic effect for susceptibility; Models 2 and 4 also included a genetic effect for infectivity, while Models 1 and 2 included a farm*period interaction. We corrected for variation in exposure to infectious herd mates via an offset. Results GEBV for \documentclass[12pt]{minimal}
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\begin{document}$$ R_{0} $$\end{document}R0 from the model that included genetic effects for susceptibility only had an accuracy of ~ 0.39 based on cross-validation between farms, which is very high given the limited amount of data and the complexity of the trait. Models with a genetic effect for infectivity showed a larger bias, but also a slightly higher accuracy of GEBV. Additive genetic standard deviation for \documentclass[12pt]{minimal}
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\begin{document}$$ R_{0} $$\end{document}R0 was large, i.e. ~ 1.17, while the mean \documentclass[12pt]{minimal}
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\begin{document}$$ R_{0} $$\end{document}R0 was 2.36. Conclusions GEBV for \documentclass[12pt]{minimal}
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\begin{document}$$ R_{0} $$\end{document}R0 showed substantial variation. The mean \documentclass[12pt]{minimal}
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\begin{document}$$ R_{0} $$\end{document}R0 was only about one genetic standard deviation greater than 1. These results suggest that lowering DD prevalence by selective breeding is promising.
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Affiliation(s)
- Floor Biemans
- Quantitative Veterinary Epidemiology, Wageningen University and Research, P.O. Box 338, 6700AH, Wageningen, The Netherlands. .,Animal Breeding and Genomics, Wageningen University and Research, P.O. Box 338, 6700AH, Wageningen, The Netherlands.
| | - Mart C M de Jong
- Quantitative Veterinary Epidemiology, Wageningen University and Research, P.O. Box 338, 6700AH, Wageningen, The Netherlands
| | - Piter Bijma
- Animal Breeding and Genomics, Wageningen University and Research, P.O. Box 338, 6700AH, Wageningen, The Netherlands
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13
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Corbett CS, de Jong MCM, Orsel K, De Buck J, Barkema HW. Quantifying transmission of Mycobacterium avium subsp. paratuberculosis among group-housed dairy calves. Vet Res 2019; 50:60. [PMID: 31429807 PMCID: PMC6701154 DOI: 10.1186/s13567-019-0678-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 08/01/2019] [Indexed: 11/10/2022] Open
Abstract
Johne’s disease (JD) is a chronic enteritis caused by Mycobacterium avium subsp. paratuberculosis (MAP), with control primarily aimed at preventing new infections among calves. The aim of the current study was to quantify calf-to-calf transmission of MAP among penmates in an experimental trial. Newborn Holstein bull calves (n = 32) were allocated into pens of 4, with 2 inoculated (IN) calves and 2 calves that were contact exposed (CE). Calves were group-housed for 3 months, with frequent collection of fecal and blood samples and tissue collection after euthanasia. The basic reproduction ratio (R0) was estimated using a final size (FS) model with a susceptible-infected model, based on INF-γ ELISA and tissue culture followed by qPCR. In addition, the transmission rate parameter (β) for new shedding events was estimated using a general linearized method (GLM) model with a susceptible-infected-susceptible model based on culture, followed by qPCR, of fecal samples collected during group housing. The R0 was derived for IN and CE calves separately, due to a difference in susceptibility, as well as differences in duration of shedding events. Based on the FS model, interferon-γ results from blood samples resulted in a R0IG of 0.90 (0.24, 2.59) and tissue culture resulted in a R0T of 1.36 (0.45, 3.94). Based on the GLM model, the R0 for CE calves to begin shedding (R0CE) was 3.24 (1.14, 7.41). We concluded that transmission of MAP infection between penmates occurred and that transmission among calves may be an important cause of persistent MAP infection on dairy farms that is currently uncontrolled for in current JD control programs.
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Affiliation(s)
- Caroline S Corbett
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Mart C M de Jong
- Quantitative Veterinary Epidemiology, Wageningen University, Droevendaalsesteeg 1, 6702 WD, Wageningen, The Netherlands
| | - Karin Orsel
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Jeroen De Buck
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Herman W Barkema
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada.
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14
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Xiong J, Zhu Q, Yang S, Zhao Y, Cui L, Zhuang F, Qiu Y, Cao J. Comparison of pharmacokinetics of tilmicosin in healthy pigs and pigs experimentally infected with Actinobacillus pleuropneumoniae. N Z Vet J 2019; 67:257-263. [PMID: 31208293 DOI: 10.1080/00480169.2019.1633434] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Aim: To compare the pharmacokinetic profiles of tilmicosin, administered orally at a single dose of 20 mg/kg bodyweight, in healthy pigs and in pigs experimentally infected with Actinobacillus pleuropneumoniae. Methods: Twelve healthy crossbred pigs, aged approximately 8 weeks, were randomly assigned to uninfected and infected groups, with six pigs per group. Pigs in the infected group were inoculated intranasally with a bacterial suspension of A. pleuropneumoniae containing approximately 108 cfu. Each pig received a single oral dose of 20 mg/kg bodyweight of tilmicosin, given 3-4 hours after inoculation in infected pigs. Blood samples were collected before drug administration and up to 48 hours after tilmicosin administration. Concentrations of tilmicosin in plasma samples were determined by HPLC. Throughout the experimental period pigs were observed for signs of inappetence and clinical abnormalities. After sampling was complete pigs were subject to euthanasia and samples collected for gross and histopathology as well as microbiology. Results: Infected pigs showed signs of bradykinesia, nasal discharge dyspnoea, and coughing 1 hours after inoculation and A. pleuropneumoniae was cultured from the lungs of all infected pigs postmortem. Comparing pharmacokinetic parameters in uninfected and infected pigs, the maximum plasma concentration of tilmicosin was higher in uninfected pigs (1.17 (SD 0.17) vs. 0.96 (SD 0.17) µg/mL), the time to reach maximum concentration was shorter (1.53 (SD 0.23) vs. 2.40 (SD 0.37) hours), and the half-life of the absorption phase and half-life of the elimination phase were both shorter (0.66 (SD 0.08) vs. 1.00 (SD 0.27) hours) and (12.93 (SD 0.96) vs. 16.53 (SD 0.55) hours), respectively. The apparent volume of distribution was smaller in uninfected than infected pigs (1.91 (SD 0.22) vs. 2.16 (SD 0.21) L/kg). The relative bioavailability of tilmicosin in infected relative to uninfected pigs was 108.6 (SD 9.71)%. Conclusions and clinical relevance: The results of this study indicate that A. pleuropneumoniae infection significantly changed certain pharmacokinetic parameters of tilmicosin in pigs. In infected pigs tilmicosin exhibited a longer drug persistence and a better extent of absorption. These results indicate that it is necessary to monitor and adjust the dose of tilmicosin administration during the presence of pleuropneumonia. It is expected that this can optimise clinical efficacy and help avoid the development of resistance.
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Affiliation(s)
- J Xiong
- a Department of Veterinary Pharmacology, College of Veterinary Medicine , Huazhong Agricultural University , Wuhan , People's Republic of China
| | - Q Zhu
- a Department of Veterinary Pharmacology, College of Veterinary Medicine , Huazhong Agricultural University , Wuhan , People's Republic of China
| | - S Yang
- a Department of Veterinary Pharmacology, College of Veterinary Medicine , Huazhong Agricultural University , Wuhan , People's Republic of China
| | - Y Zhao
- a Department of Veterinary Pharmacology, College of Veterinary Medicine , Huazhong Agricultural University , Wuhan , People's Republic of China
| | - L Cui
- b Department of Veterinary Pathology, College of Veterinary Medicine , Huazhong Agricultural University , Wuhan , People's Republic of China
| | - F Zhuang
- c Hubei Key Laboratory of Animal Nutrition and Feed Science , Hubei Collaborative Innovation Centre for Animal Nutrition and Feed Safety, Wuhan Polytechnic University , Wuhan , People's Republic of China
| | - Y Qiu
- c Hubei Key Laboratory of Animal Nutrition and Feed Science , Hubei Collaborative Innovation Centre for Animal Nutrition and Feed Safety, Wuhan Polytechnic University , Wuhan , People's Republic of China
| | - J Cao
- a Department of Veterinary Pharmacology, College of Veterinary Medicine , Huazhong Agricultural University , Wuhan , People's Republic of China
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15
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Biemans F, de Jong MCM, Bijma P. A genome-wide association study for susceptibility and infectivity of Holstein Friesian dairy cattle to digital dermatitis. J Dairy Sci 2019; 102:6248-6262. [PMID: 31103307 DOI: 10.3168/jds.2018-15876] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 03/19/2019] [Indexed: 12/21/2022]
Abstract
Selection and breeding can be used to fight transmission of infectious diseases in livestock. The prevalence in a population depends on the susceptibility and infectivity of the animals. Knowledge on the genetic background of those traits would facilitate efficient selection for lower disease prevalence. We investigated the genetic background of host susceptibility and infectivity for digital dermatitis (DD), an endemic infectious claw disease in dairy cattle, with a genome-wide association study (GWAS), using either a simple linear mixed model or a generalized linear mixed model based on epidemiological theory. In total, 1,513 Holstein-Friesian cows of 12 Dutch dairy farms were scored for DD infection status and class (M0 to M4.1) every 2 wk for 11 times; 1,401 of these cows were genotyped with a 75k SNP chip. We performed a GWAS with a linear mixed model on 10 host disease status traits, and with a generalized linear mixed model with a complementary log-log link function (GLMM) on the probability that a cow would get infected between 2 scorings. With the GLMM, we fitted SNP effects for host susceptibility and host infectivity, while taking the variation in exposure of the susceptible cow to infectious herd mates into account. With the linear model we detected 4 suggestive SNP (false discovery rate < 0.20), 2 for the fraction of observations a cow had an active lesion on chromosomes 1 and 14, one for the fraction of observations a cow had an M2 lesion on at least one claw on chromosome 1 (the same SNP as for the fraction of observations with an active lesion), and one for the fraction of observations a cow had an M4.1 lesion on at least one claw on chromosome 10. Heritability estimates ranged from 0.09 to 0.37. With the GLMM we did not detect significant nor suggestive SNP. The SNP effects on disease status analyzed with the linear model had a correlation coefficient of only 0.70 with SNP effects on susceptibility of the GLMM, indicating that both models capture partly different effects. Because the GLMM better accounts for the epidemiological mechanisms determining individual disease status and for the distribution of the y-variable, results of the GLMM may be more reliable, despite the absence of suggestive associations. We expect that with an extended GLMM that better accounts for the full genetic variation in infectivity via the environment, the accuracy of SNP effects may increase.
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Affiliation(s)
- F Biemans
- Quantitative Veterinary Epidemiology, Wageningen University and Research, 6700 AH Wageningen, the Netherlands; Animal Breeding and Genomics, Wageningen University and Research, 6700 AH Wageningen, the Netherlands.
| | - M C M de Jong
- Quantitative Veterinary Epidemiology, Wageningen University and Research, 6700 AH Wageningen, the Netherlands
| | - P Bijma
- Animal Breeding and Genomics, Wageningen University and Research, 6700 AH Wageningen, the Netherlands
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16
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Xiong J, Zhu Q, Zhao Y, Yang S, Cao J, Qiu Y. Tilmicosin enteric granules and premix to pigs: Antimicrobial susceptibility testing and comparative pharmacokinetics. J Vet Pharmacol Ther 2019; 42:336-345. [PMID: 30801755 DOI: 10.1111/jvp.12753] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 01/22/2019] [Accepted: 01/28/2019] [Indexed: 11/28/2022]
Abstract
The purpose of this study was to compare the pharmacokinetics and relative bioavailability of tilmicosin enteric granules and premix after oral administration at a dose of 40 mg/kg in pigs. Three kinds of different respiratory pathogens were selected for determination of minimal inhibitory concentration (MIC) to tilmicosin. Eight healthy pigs were assigned to a two-period, randomized crossover design. A modified rapid, sensitive HPLC method was used for determining the concentrations of tilmicosin in plasma. Pharmacokinetic parameters were calculated by using WinNonlin 5.2 software. The MIC90 of tilmicosin against Haemophilus parasuis, Actinbacillus pleuropneumoniae, and Pasteurella multocida were all 8 μg/ml. These results indicated that these common pig respiratory bacteria are sensitive to tilmicosin. The main parameters of time to reach maximum plasma concentration (Tmax ), elimination half-life (t1/2β ), mean residence time (MRT), and apparent volume of distribution (VF ) were 2.03 ± 0.37 hr, 29.31 ± 5.56 hr, 25.22 ± 2.57 hr, 4.06 ± 1.04 L/kg, and 3.05 ± 0.08 hr, 17.06 ± 1.77 hr, 15.55 ± 1.37 hr, 2.95 ± 0.62 L/kg after the orally administrated tilmicosin enteric granules and premix. The relative bioavailability of tilmicosin enteric granules to premix was 114.97 ± 7.19%, according to the AUC0-t values. These results demonstrated that tilmicosin enteric granules produced faster tilmicosin absorption, slower elimination, larger tissue distribution, and higher bioavailability compared to the tilmicosin premix. The present study results manifest that tilmicosin enteric granules can be used as a therapeutic alternative to premix in clinical treatment.
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Affiliation(s)
- Jincheng Xiong
- Department of Veterinary Pharmacology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,National Reference Laboratory of Veterinary Drug Residues and Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, China
| | - Qianqian Zhu
- Department of Veterinary Pharmacology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,National Reference Laboratory of Veterinary Drug Residues and Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, China
| | - Yaxin Zhao
- Department of Veterinary Pharmacology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Shuaike Yang
- Department of Veterinary Pharmacology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,National Reference Laboratory of Veterinary Drug Residues and Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, China
| | - Jiyue Cao
- Department of Veterinary Pharmacology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,National Reference Laboratory of Veterinary Drug Residues and Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, China
| | - Yinsheng Qiu
- Hubei Key Laboratory of Animal Nutrition and Feed Science, Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Wuhan Polytechnic University, Wuhan, China
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17
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Tadesse B, Molla W, Mengsitu A, Jemberu WT. Transmission dynamics of foot and mouth disease in selected outbreak areas of northwest Ethiopia. Epidemiol Infect 2019; 147:e189. [PMID: 31364529 PMCID: PMC6518559 DOI: 10.1017/s0950268819000803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 03/29/2019] [Accepted: 04/06/2019] [Indexed: 11/05/2022] Open
Abstract
Foot and mouth disease (FMD) is a highly contagious and economically important disease of cloven-hoofed animals, which is endemic in Ethiopia. An outbreak follow-up study was undertaken to quantify the transmission parameters of FMD in the crop-livestock mixed (CLM) system and commercial dairy farms in selected areas of northwest Ethiopia. The transmission parameters were quantified using a generalised linear model (GLM) based on a susceptible-infectious-recovered (SIR) epidemic model. The per day average transmission rate between animals was 0.26 (95% CI 0.22-0.32) and 0.33 (95% CI 0.21-0.57) in the CLM system and in the commercial dairy farms, respectively. The average basic reproduction ratio of FMD was 1.68 (95% CI 1.42-2.07) in the CLM system and 1.98 (95% CI 1.26-3.42) in the commercial dairy farms. The medium per day transmission rate and moderate basic reproduction ratio observed in this study indicated that a vaccination coverage needed to stop transmission of the disease in these populations might not be very high.
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Affiliation(s)
- B. Tadesse
- University of Gondar, College of Veterinary Medicine and Animal Sciences, Department of Veterinary Epidemiology and Public Health, P.O. Box. 196, Gondar, Ethiopia
- Amedguya Sheep Breed Improvement and Multiplication Center, P.O. Box. 30, North Shoa, Ethiopia
| | - W. Molla
- University of Gondar, College of Veterinary Medicine and Animal Sciences, Department of Veterinary Epidemiology and Public Health, P.O. Box. 196, Gondar, Ethiopia
| | - A. Mengsitu
- University of Gondar, College of Veterinary Medicine and Animal Sciences, Department of Veterinary Epidemiology and Public Health, P.O. Box. 196, Gondar, Ethiopia
| | - W. T. Jemberu
- University of Gondar, College of Veterinary Medicine and Animal Sciences, Department of Veterinary Epidemiology and Public Health, P.O. Box. 196, Gondar, Ethiopia
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18
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Brown PA, Courtillon C, Weerts EAWS, Andraud M, Allée C, Vendembeuche A, Amelot M, Rose N, Verheije MH, Eterradossi N. Transmission Kinetics and histopathology induced by European Turkey Coronavirus during experimental infection of specific pathogen free turkeys. Transbound Emerg Dis 2018; 66:234-242. [PMID: 30146717 PMCID: PMC7138094 DOI: 10.1111/tbed.13006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 08/14/2018] [Accepted: 08/18/2018] [Indexed: 12/15/2022]
Abstract
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 (ID50), transmission kinetics and pathogenicity of Fr‐TCoV were investigated in 10‐day‐old SPF turkeys. Results revealed a titre of 104.88ID50/ml with 1 ID50/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 the intestinal tract with an abundance of viral antigen being present in epithelial cells of the ileum, caecum and bursa of Fabricius. Viral antigen was also detected in dendritic cells, monocytes and macrophages in these areas, which may indicate a potential for Fr‐TCoV to replicate in antigen‐presenting cells. Together these results highlight the importance of good sanitary practices in turkey farms to avoid introducing minute amounts of virus that could suffice to initiate an outbreak, and the need to consider that infected individuals may still be infectious long after a clinical episode, to avoid virus dissemination through the movements of apparently recovered birds.
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Affiliation(s)
- Paul A Brown
- VIPAC Unit, Agence Nationale de Sécurité Sanitaire (ANSES), Laboratoire de Ploufragan-Plouzané, Université Bretagne Loire, Ploufragan, France.,EPICOREM Consortium, Unité de Recherche Risques Microbiens (U2RM), Université de Caen, Caen, France
| | - Céline Courtillon
- VIPAC Unit, Agence Nationale de Sécurité Sanitaire (ANSES), Laboratoire de Ploufragan-Plouzané, Université Bretagne Loire, Ploufragan, France.,EPICOREM Consortium, Unité de Recherche Risques Microbiens (U2RM), Université de Caen, Caen, France
| | - Erik A W S Weerts
- Faculty of Veterinary Medicine, Department of Pathobiology, Utrecht University, Utrecht, Netherlands
| | - Mathieu Andraud
- EBEP Unit, Agence Nationale de Sécurité Sanitaire (ANSES), Laboratoire de Ploufragan-Plouzané, Université Bretagne Loire, Ploufragan, France
| | - Chantal Allée
- VIPAC Unit, Agence Nationale de Sécurité Sanitaire (ANSES), Laboratoire de Ploufragan-Plouzané, Université Bretagne Loire, Ploufragan, France.,EPICOREM Consortium, Unité de Recherche Risques Microbiens (U2RM), Université de Caen, Caen, France
| | - Anthony Vendembeuche
- SELEAC Unit, Agence Nationale de Sécurité Sanitaire (ANSES), Laboratoire de Ploufragan-Plouzané, Université Bretagne Loire, Ploufragan, France
| | - Michel Amelot
- SELEAC Unit, Agence Nationale de Sécurité Sanitaire (ANSES), Laboratoire de Ploufragan-Plouzané, Université Bretagne Loire, Ploufragan, France
| | - Nicolas Rose
- EBEP Unit, Agence Nationale de Sécurité Sanitaire (ANSES), Laboratoire de Ploufragan-Plouzané, Université Bretagne Loire, Ploufragan, France
| | - Monique H Verheije
- Faculty of Veterinary Medicine, Department of Pathobiology, Utrecht University, Utrecht, Netherlands
| | - Nicolas Eterradossi
- VIPAC Unit, Agence Nationale de Sécurité Sanitaire (ANSES), Laboratoire de Ploufragan-Plouzané, Université Bretagne Loire, Ploufragan, France.,EPICOREM Consortium, Unité de Recherche Risques Microbiens (U2RM), Université de Caen, Caen, France
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19
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Hoeltig D, Rohde J, Brunner B, Hellmann K, Grandemange E, Waldmann KH. Efficacy of a one-shot marbofloxacin treatment on acute pleuropneumonia after experimental aerosol inoculation of nursery pigs. Porcine Health Manag 2018; 4:13. [PMID: 29977591 PMCID: PMC6013868 DOI: 10.1186/s40813-018-0089-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 05/29/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Porcine pleuropneumonia, caused by Actinobacillus pleuropneumoniae, is a bacterial respiratory disease of swine. Acute outbreaks of the disease are often accompanied by high mortality and economic losses. As severe cases of the disease frequently require parenteral antibiotic treatment of the animals, the efficacy of a single, high dose of marbofloxacin was compared to a three-time application of a dose of enrofloxacin under experimental conditions. METHODS A blinded, controlled, randomized and blocked dose confirmation study was conducted to test the efficacy and safety of a single dose of 8 mg/kg marbofloxacin (160 mg/ml, Forcyl® Swine, Vetoquinol SA, France) to treat acute porcine pleuropneumonia after experimental aerosol inoculation of pigs with A. pleuropneumoniae serotype 2. The results were compared to a three consecutive day treatment of 2.5 mg/kg enrofloxacin and a mock (saline) treatment. Criteria for the assessment of efficacy were severity of lung lesions, bacteriological cure and the course of clinical disease after treatment. RESULTS Thirty six nursery pigs were divided into three treatment groups: marbofloxacin (T1), enrofloxacin (T2) and mock (T3). Statistically significant superiority (p < 0.05) of marbofloxacin and enrofloxacin compared to the mock-treated group was demonstrated for all efficacy criteria. The need of rescue euthanasia due to severity of symptoms was significantly reduced in both treatment groups (T1: 1 pig; T2: 0 pigs; vs. T3: 8 pigs). On day 6 after treatment initiation, clinical cure was observed in 10 (T1), 10 (T2) but only 1 of the piglets in T3. Extent of lung lesions (mean of lung lesion score T1: 3.9, T2: 6.0, T3: 21.1) and bacteriological isolation from lung tissue (on day 6 after treatment initiation: T1 = 0 pigs; T2 = 1 pig; T3 = all pigs) were also significantly reduced within both treatment groups. There were no adverse events linked to the drug administration and no injection site reactions were observed. CONCLUSIONS Both applied antimicrobial treatments were proven safe and efficacious for the treatment of acute porcine pleuropneumonia. No statistically significant differences were detected between the antibiotic treatments.
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Affiliation(s)
- Doris Hoeltig
- Clinic for Swine, Small Ruminants, forensic Medicine and Ambulatory Service, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, D-30173 Hannover, Germany
| | - Judith Rohde
- Institute for Microbiology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, D-30173 Hannover, Germany
| | - Birgit Brunner
- Klifovet AG, Geyerspergerstr. 27, D-80689 Munich, Germany
| | - Klaus Hellmann
- Klifovet AG, Geyerspergerstr. 27, D-80689 Munich, Germany
| | - Erik Grandemange
- Vetoquinol SA, Research and Development Centre, B.P. 189, Cedex 70204 Lure, France
| | - Karl-Heinz Waldmann
- Clinic for Swine, Small Ruminants, forensic Medicine and Ambulatory Service, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, D-30173 Hannover, Germany
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20
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Digital Dermatitis in dairy cattle: The contribution of different disease classes to transmission. Epidemics 2017; 23:76-84. [PMID: 29279186 DOI: 10.1016/j.epidem.2017.12.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 12/13/2017] [Accepted: 12/21/2017] [Indexed: 11/23/2022] Open
Abstract
Digital Dermatitis (DD) is a claw disease mainly affecting the hind feet of dairy cattle. Digital Dermatitis is an infectious disease, transmitted via the environment, where the infectious "agent" is a combination of bacteria. The standardized classification for DD lesions developed by Döpfer et al. (1997) and extended by Berry et al. (2012) has six distinct classes: healthy (M0), an active granulomatous area of 0-2 cm (M1), an ulcerative lesion of >2 cm (M2), an ulcerative lesion covered by a scab (M3), alteration of the skin (M4), and a combination of M4 and M1 (M4.1). We hypothesize that classes M1, M2, M3, M4, and M4.1 are the potentially infectious classes that can contribute to the basic reproduction ratio (R0), the average number of new infections caused by a typical infected individual. Here, we determine differences in infectivity between the classes, the sojourn time in each of the classes, and the contribution of each class to R0. The analysis is based on data from twelve farms in the Netherlands that were visited every two weeks, eleven times. We found that 93.89% of the transitions from M0 was observed as a transition to class M4, and feet with another class-at-infection rapidly transitioned to class M4. As a consequence, about 70% of the infectious time was spent in class M4. Transmission rate parameters of class-at-infection M1, M2, M3, and M4 were not significantly different from each other, but differed from class-at-infection M4.1. However, due to the relative large amount of time spend in class M4, regardless of the class-at-infection, R0 was almost completely determined by this class. The R0 was 2.36, to which class-at-infection M4 alone contributed 88.5%. Thus, M4 lesions should be prevented to lower R0 to a value below one, while painful M2 lesions should be prevented for animal welfare reasons.
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Sassu EL, Bossé JT, Tobias TJ, Gottschalk M, Langford PR, Hennig-Pauka I. Update on Actinobacillus pleuropneumoniae-knowledge, gaps and challenges. Transbound Emerg Dis 2017; 65 Suppl 1:72-90. [PMID: 29083117 DOI: 10.1111/tbed.12739] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Indexed: 12/15/2022]
Abstract
Porcine pleuropneumonia, caused by the bacterial porcine respiratory tract pathogen Actinobacillus pleuropneumoniae, leads to high economic losses in affected swine herds in most countries of the world. Pigs affected by peracute and acute disease suffer from severe respiratory distress with high lethality. The agent was first described in 1957 and, since then, knowledge about the pathogen itself, and its interactions with the host, has increased continuously. This is, in part, due to the fact that experimental infections can be studied in the natural host. However, the fact that most commercial pigs are colonized by this pathogen has hampered the applicability of knowledge gained under experimental conditions. In addition, several factors are involved in development of disease, and these have often been studied individually. In a DISCONTOOLS initiative, members from science, industry and clinics exchanged their expertise and empirical observations and identified the major gaps in knowledge. This review sums up published results and expert opinions, within the fields of pathogenesis, epidemiology, transmission, immune response to infection, as well as the main means of prevention, detection and control. The gaps that still remain to be filled are highlighted, and present as well as future challenges in the control of this disease are addressed.
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Affiliation(s)
- E L Sassu
- Department of Pathobiology, Institute of Immunology, University of Veterinary Medicine, Vienna, Austria
| | - J T Bossé
- Section of Paediatrics, Department of Medicine, Imperial College London, London, UK
| | - T J Tobias
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - M Gottschalk
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, Canada
| | - P R Langford
- Section of Paediatrics, Department of Medicine, Imperial College London, London, UK
| | - I Hennig-Pauka
- Field Station for Epidemiology, University of Veterinary Medicine Hannover, Foundation, Bakum, Germany
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Molla W, Frankena K, Gari G, de Jong MCM. Field study on the use of vaccination to control the occurrence of lumpy skin disease in Ethiopian cattle. Prev Vet Med 2017; 147:34-41. [PMID: 29254724 DOI: 10.1016/j.prevetmed.2017.08.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 08/22/2017] [Accepted: 08/22/2017] [Indexed: 11/28/2022]
Abstract
The current study was carried out in central and North-western parts of Ethiopia to assess the efficacy of Kenyan sheep pox virus strain vaccine (KS1 O-180) against natural lumpy skin disease (LSD) infection under field conditions by estimating its effect on the transmission and severity of the disease. For this study, an LSD outbreak was defined as the occurrence of at least one LSD case in a specified geographical area. An observational study was conducted on a total of 2053 (1304 vaccinated and 749 unvaccinated) cattle in 339 infected herds located in 10 sub-kebeles and a questionnaire survey was administered to 224 herd owners. Over 60% of the herd owners reported that the vaccine has a low to very low effect in protecting animals against clinical LSD; almost all of them indicated that the vaccine did not induce any adverse reactions. In the unvaccinated group of animals 31.1% were diagnosed with LSD while this was 22.5% in the vaccinated group (P<0.001). Severity of the disease was significantly reduced in vaccinated compared to unvaccinated animals (OR=0.68, 95% CI: 0.49; 0.96). Unvaccinated infected animals were more likely (predicted fraction=0.89) to develop moderate and severe disease than vaccinated infected animals (predicted fraction=0.84). LSD vaccine efficacy for susceptibility was estimated to be 0.46 (i.e. a susceptibility effect of 0.54) while the infectiousness effect of the vaccine was 1.83. In other words, the vaccine reduces the susceptibility by a factor of two and increases infectiousness by approximately the same amount. LSD transmission occurred in both vaccinated and unvaccinated animals, the estimated reproduction ratio (R) was 1.21 in unvaccinated animals compared to 1.19 in vaccinated ones, and not significantly different. In conclusion, KS1 O-180 vaccination, as applied currently in Ethiopia, has poor efficacy in protecting cattle populations against LSD, neither by direct clinical protection nor by reducing transmission, and this signifies the urgent need to either improve the quality of the vaccine or to develop potent alternative vaccines that will confer good protection against LSD.
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Affiliation(s)
- Wassie Molla
- Quantitative Veterinary Epidemiology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands; Faculty of Veterinary Medicine, University of Gondar, P.O. Box 196, Gondar, Ethiopia.
| | - Klaas Frankena
- Quantitative Veterinary Epidemiology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
| | - Getachew Gari
- National Animal Health Diagnostic and Investigation Centre (NAHDIC), Sebeta, Ethiopia
| | - Mart C M de Jong
- Quantitative Veterinary Epidemiology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
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Effect of Simultaneous Exposure of Pigs to Streptococcus suis Serotypes 2 and 9 on Their Colonization and Transmission, and on Mortality. Pathogens 2017; 6:pathogens6040046. [PMID: 28953248 PMCID: PMC5750570 DOI: 10.3390/pathogens6040046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 09/22/2017] [Accepted: 09/26/2017] [Indexed: 01/13/2023] Open
Abstract
The distribution of Streptococcus suis serotypes isolated from clinically infected pigs differs between geographical areas, and varies over time. In several European countries, predomination of serotype 2 has changed to serotype 9. We hypothesize a relation, with one serotype affecting the other in colonization and invasion. The aim of this study was to evaluate whether simultaneous exposure of pigs to serotypes 2 and 9 affects colonization and transmission of each type, and mortality. Thirty-six caesarean-derived/colostrum-deprived piglets were randomly assigned to three groups, and there housed pair-wise. At six weeks old, one pig per pair was inoculated with either one (serotype 2 or 9; mono-group) or two serotypes simultaneously (dual-group); the other pig was contact-exposed. Tonsillar and nasal samples were collected within three weeks post inoculation. Bacterial loads in samples were quantified using multiplex real-time polymerase chain reaction (PCR). Transmission rates of the serotypes among pigs were estimated using a mathematical Susceptible-Infectious (SI) model. Bacterial loads and transmission rates did not differ significantly between serotypes. Compared to the mono-group, in the dual-group the average serotype 2 load in tonsillar samples from contact pigs was reduced on days 1 to 4 and on day 6. Simultaneous exposure to the serotypes reduced the mortality hazard 6.3 times (95% C.I.: 2.0–19.8) compared to exposure to serotype 2 only, and increased it 6.6 times (95% C.I.: 1.4–30.9) compared to exposure to serotype 9 only. This study indicates that serotype 2 load and mortality were affected in pigs exposed to these two serotypes.
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Abstract
SUMMARYLumpy skin disease (LSD) is a severe disease of cattle caused by a Capripoxvirus and often caused epidemics in Ethiopia and many other countries. This study was undertaken to quantify the transmission between animals and to estimate the infection reproduction ratio in a predominantly mixed crop–livestock system and in intensive commercial herd types. The transmission parameters were based on a susceptible-infectious-recovered (SIR) epidemic model with environmental transmission and estimated using generalized linear models. The transmission parameters were estimated using a survival rate of infectious virus in the environment equal to 0·325 per day, a value based on the best-fitting statistical model. The transmission rate parameter between animals was 0·072 (95% CI 0·068–0·076) per day in the crop–livestock production system, whereas this transmission rate in intensive production system was 0·076 (95% CI 0·068–0·085) per day. The reproduction ratio (R) of LSD between animals in the crop–livestock production system was 1·07, whereas it was 1·09 between animals in the intensive production system. The calculated R provides a baseline against which various control options can be assessed for efficacy.
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Estimation of the transmission dynamics of African swine fever virus within a swine house. Epidemiol Infect 2017; 145:2787-2796. [DOI: 10.1017/s0950268817001613] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
SUMMARYThe spread of African swine fever virus (ASFV) threatens to reach further parts of Europe. In countries with a large swine production, an outbreak of ASF may result in devastating economic consequences for the swine industry. Simulation models can assist decision makers setting up contingency plans. This creates a need for estimation of parameters. This study presents a new analysis of a previously published study. A full likelihood framework is presented including the impact of model assumptions on the estimated transmission parameters. As animals were only tested every other day, an interpretation was introduced to cover the weighted infectiousness on unobserved days for the individual animals (WIU). Based on our model and the set of assumptions, the within- and between-pen transmission parameters were estimated to βw = 1·05 (95% CI 0·62–1·72), βb = 0·46 (95% CI 0·17–1·00), respectively, and the WIU = 1·00 (95% CI 0–1). Furthermore, we simulated the spread of ASFV within a pig house using a modified SEIR-model to establish the time from infection of one animal until ASFV is detected in the herd. Based on a chosen detection limit of 2·55% equivalent to 10 dead pigs out of 360, the disease would be detected 13–19 days after introduction.
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Biemans F, de Jong MCM, Bijma P. A model to estimate effects of SNPs on host susceptibility and infectivity for an endemic infectious disease. Genet Sel Evol 2017; 49:53. [PMID: 28666475 PMCID: PMC5492932 DOI: 10.1186/s12711-017-0327-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 06/21/2017] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Infectious diseases in farm animals affect animal health, decrease animal welfare and can affect human health. Selection and breeding of host individuals with desirable traits regarding infectious diseases can help to fight disease transmission, which is affected by two types of (genetic) traits: host susceptibility and host infectivity. Quantitative genetic studies on infectious diseases generally connect an individual's disease status to its own genotype, and therefore capture genetic effects on susceptibility only. However, they usually ignore variation in exposure to infectious herd mates, which may limit the accuracy of estimates of genetic effects on susceptibility. Moreover, genetic effects on infectivity will exist as well. Thus, to design optimal breeding strategies, it is essential that genetic effects on infectivity are quantified. Given the potential importance of genetic effects on infectivity, we set out to develop a model to estimate the effect of single nucleotide polymorphisms (SNPs) on both host susceptibility and host infectivity. To evaluate the quality of the resulting SNP effect estimates, we simulated an endemic disease in 10 groups of 100 individuals, and recorded time-series data on individual disease status. We quantified bias and precision of the estimates for different sizes of SNP effects, and identified the optimum recording interval when the number of records is limited. RESULTS We present a generalized linear mixed model to estimate the effect of SNPs on both host susceptibility and host infectivity. SNP effects were on average slightly underestimated, i.e. estimates were conservative. Estimates were less precise for infectivity than for susceptibility. Given our sample size, the power to estimate SNP effects for susceptibility was 100% for differences between genotypes of a factor 1.56 or more, and was higher than 60% for infectivity for differences between genotypes of a factor 4 or more. When disease status was recorded 11 times on each animal, the optimal recording interval was 25 to 50% of the average infectious period. CONCLUSIONS Our model was able to estimate genetic effects on susceptibility and infectivity. In future genome-wide association studies, it may serve as a starting point to identify genes that affect disease transmission and disease prevalence.
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Affiliation(s)
- Floor Biemans
- Quantitative Veterinary Epidemiology Group, Wageningen University and Research, Wageningen, The Netherlands
- Animal Breeding and Genomics Centre, Wageningen University and Research, Wageningen, The Netherlands
| | - Mart C. M. de Jong
- Quantitative Veterinary Epidemiology Group, Wageningen University and Research, Wageningen, The Netherlands
| | - Piter Bijma
- Animal Breeding and Genomics Centre, Wageningen University and Research, Wageningen, The Netherlands
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Rose N, Andraud M. The use of vaccines to control pathogen spread in pig populations. Porcine Health Manag 2017; 3:8. [PMID: 28405464 PMCID: PMC5382368 DOI: 10.1186/s40813-017-0053-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 02/08/2017] [Indexed: 01/13/2023] Open
Abstract
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 pathogen characteristics in terms of diffusion (\documentclass[12pt]{minimal}
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\begin{document}$$ {R}_0 $$\end{document}R0). Before setting up vaccination programmes, it is therefore necessary to have quantitative knowledge on vaccine efficacy as regards transmission reduction. These data can be obtained by carrying out experimental studies or observational protocols in real conditions. These quantitative data have mainly been estimated for major infectious diseases which have now been eradicated. A great gap in knowledge has however been identified for enzootic diseases which are daily impacting the swine sector as well as for the source of variation responsible for a decrease in vaccine efficacy as compared to assessments obtained in experimental conditions.
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Affiliation(s)
- Nicolas Rose
- Anses-Laboratoire de Ploufragan-Plouzané, Swine Epidemiology and Welfare Research Unit, Po Box 53, F22440 Ploufragan, France ; Université Bretagne Loire, Rennes, France
| | - Mathieu Andraud
- Anses-Laboratoire de Ploufragan-Plouzané, Swine Epidemiology and Welfare Research Unit, Po Box 53, F22440 Ploufragan, France ; Université Bretagne Loire, Rennes, France
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28
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van den Borne BHP, Graber HU, Voelk V, Sartori C, Steiner A, Haerdi-Landerer MC, Bodmer M. A longitudinal study on transmission of Staphylococcus aureus genotype B in Swiss communal dairy herds. Prev Vet Med 2016; 136:65-68. [PMID: 27890338 DOI: 10.1016/j.prevetmed.2016.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 11/04/2016] [Accepted: 11/15/2016] [Indexed: 10/20/2022]
Abstract
Staphylococcus aureus is a common mastitis causing pathogen of dairy cattle. Several S. aureus genotypes exist, of which genotype B (GTB) is highly prevalent in Swiss dairy herds. Dairy farming in mountainous regions of Switzerland is characterised by the movement of dairy cattle to communal pasture-based operations at higher altitudes. Cows from different herds of origin share pastures and milking equipment for a period of 2 to 3 months during summer. The aim of this longitudinal observational study was to quantify transmission of S. aureus GTB in communal dairy operations. Cows (n=551) belonging to 7 communal operations were sampled at the beginning and end of the communal period. Transmission parameter β was estimated using a Susceptible-Infectious-Susceptible (SIS) model. The basic reproduction ratio R0 was subsequently derived using previously published information about the duration of infection. Mean transmission parameter β was estimated to be 0.0232 (95% CI: 0.0197-0.0274). R0 was 2.6 (95% CI: 2.2-3.0), indicating that S. aureus GTB is capable of causing major outbreaks in Swiss communal dairy operations. This study emphasized the contagious behaviour of S. aureus GTB. Mastitis management in communal dairy operations should be optimized to reduce S. aureus GTB transmission between cows and back to their herds of origin.
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Affiliation(s)
- Bart H P van den Borne
- Veterinary Public Health Institute, Vetsuisse Faculty, University of Bern, Schwarzenburgstrasse 151, 3097 Liebefeld, Switzerland.
| | - Hans U Graber
- Agroscope, Institute for Food Sciences, Schwarzenburgstrasse 161, 3003 Bern, Switzerland
| | - Verena Voelk
- Clinic for Ruminants, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, 3012 Bern, Switzerland
| | - Carlotta Sartori
- Agroscope, Institute for Food Sciences, Schwarzenburgstrasse 161, 3003 Bern, Switzerland
| | - Adrian Steiner
- Clinic for Ruminants, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, 3012 Bern, Switzerland
| | | | - Michèle Bodmer
- Clinic for Ruminants, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, 3012 Bern, Switzerland
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Sitaras I, Rousou X, Kalthoff D, Beer M, Peeters B, de Jong MCM. Role of vaccination-induced immunity and antigenic distance in the transmission dynamics of highly pathogenic avian influenza H5N1. J R Soc Interface 2016; 13:20150976. [PMID: 26763336 DOI: 10.1098/rsif.2015.0976] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Highly pathogenic avian influenza (HPAI) H5N1 epidemics in poultry cause huge economic losses as well as sporadic human morbidity and mortality. Vaccination in poultry has often been reported as being ineffective in preventing transmission and as a potential driving force in the selection of immune escape mutants. We conducted transmission experiments to evaluate the transmission dynamics of HPAI H5N1 strains in chickens vaccinated with high and low doses of immune escape mutants we have previously selected, and analysed the data using mathematical models. Remarkably, we demonstrate that the effect of antigenic distances between the vaccine and challenge strains used in this study is too small to influence the transmission dynamics of the strains used. This is because the effect of a sufficient vaccine dose on antibody levels against the challenge viruses is large enough to compensate for any decrease in antibody titres due to antigenic differences between vaccine and challenge strains. Our results show that at least under experimental conditions, vaccination will remain effective even after antigenic changes as may be caused by the initial selection in vaccinated birds.
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Affiliation(s)
- Ioannis Sitaras
- Quantitative Veterinary Epidemiology, Department of Animal Sciences, Wageningen University, Radix Building 107, Droevendaalsesteeg 1, Wageningen 6708 PB, The Netherlands Department of Virology, Central Veterinary Institute of Wageningen University and Research Centre, Houtribweg 39, Lelystad 8221 RA, The Netherlands
| | - Xanthoula Rousou
- Quantitative Veterinary Epidemiology, Department of Animal Sciences, Wageningen University, Radix Building 107, Droevendaalsesteeg 1, Wageningen 6708 PB, The Netherlands
| | - Donata Kalthoff
- Institute of Diagnostic Virology, Friedrich-Löffler Institut, Südufer 10, Greifswald-Insel Riems 17493, Germany
| | - Martin Beer
- Institute of Diagnostic Virology, Friedrich-Löffler Institut, Südufer 10, Greifswald-Insel Riems 17493, Germany
| | - Ben Peeters
- Department of Virology, Central Veterinary Institute of Wageningen University and Research Centre, Houtribweg 39, Lelystad 8221 RA, The Netherlands
| | - Mart C M de Jong
- Quantitative Veterinary Epidemiology, Department of Animal Sciences, Wageningen University, Radix Building 107, Droevendaalsesteeg 1, Wageningen 6708 PB, The Netherlands
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Li B, Gong SY, Zhou XZ, Yang YJ, Li JY, Wei XJ, Cheng FS, Niu JR, Liu XW, Zhang JY. Determination of antibacterial agent tilmicosin in pig plasma by LC/MS/MS and its application to pharmacokinetics. Biomed Chromatogr 2016; 31. [DOI: 10.1002/bmc.3825] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 08/16/2016] [Accepted: 08/21/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Bing Li
- Key Laboratory of Veterinary Pharmaceutical Development; Ministry of Agriculture; Lanzhou China
- Key Laboratory of New Animal Drug Project of Gansu Province; Lanzhou China
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS; Lanzhou China
| | - Shi-Yue Gong
- China Agricultural Vet. (Tianjin) Biological Medicine Co. Ltd; Tianjin China
| | - Xu-Zheng Zhou
- Key Laboratory of Veterinary Pharmaceutical Development; Ministry of Agriculture; Lanzhou China
- Key Laboratory of New Animal Drug Project of Gansu Province; Lanzhou China
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS; Lanzhou China
| | - Ya-Jun Yang
- Key Laboratory of Veterinary Pharmaceutical Development; Ministry of Agriculture; Lanzhou China
- Key Laboratory of New Animal Drug Project of Gansu Province; Lanzhou China
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS; Lanzhou China
| | - Jian-Yong Li
- Key Laboratory of Veterinary Pharmaceutical Development; Ministry of Agriculture; Lanzhou China
- Key Laboratory of New Animal Drug Project of Gansu Province; Lanzhou China
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS; Lanzhou China
| | - Xiao-Juan Wei
- Key Laboratory of Veterinary Pharmaceutical Development; Ministry of Agriculture; Lanzhou China
- Key Laboratory of New Animal Drug Project of Gansu Province; Lanzhou China
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS; Lanzhou China
| | - Fu-Sheng Cheng
- Key Laboratory of Veterinary Pharmaceutical Development; Ministry of Agriculture; Lanzhou China
- Key Laboratory of New Animal Drug Project of Gansu Province; Lanzhou China
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS; Lanzhou China
| | - Jian-Rong Niu
- Key Laboratory of Veterinary Pharmaceutical Development; Ministry of Agriculture; Lanzhou China
- Key Laboratory of New Animal Drug Project of Gansu Province; Lanzhou China
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS; Lanzhou China
| | - Xi-Wang Liu
- Key Laboratory of Veterinary Pharmaceutical Development; Ministry of Agriculture; Lanzhou China
- Key Laboratory of New Animal Drug Project of Gansu Province; Lanzhou China
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS; Lanzhou China
| | - Ji-Yu Zhang
- Key Laboratory of Veterinary Pharmaceutical Development; Ministry of Agriculture; Lanzhou China
- Key Laboratory of New Animal Drug Project of Gansu Province; Lanzhou China
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS; Lanzhou China
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Huijbers PM, Graat EA, van Hoek AH, Veenman C, de Jong MC, van Duijkeren E. Transmission dynamics of extended-spectrum β-lactamase and AmpC β-lactamase-producing Escherichia coli in a broiler flock without antibiotic use. Prev Vet Med 2016; 131:12-19. [DOI: 10.1016/j.prevetmed.2016.07.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 06/09/2016] [Accepted: 07/01/2016] [Indexed: 11/30/2022]
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Rose N, Andraud M, Bigault L, Jestin A, Grasland B. A commercial PCV2a-based vaccine significantly reduces PCV2b transmission in experimental conditions. Vaccine 2016; 34:3738-45. [PMID: 27318416 DOI: 10.1016/j.vaccine.2016.06.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/20/2016] [Accepted: 06/01/2016] [Indexed: 10/21/2022]
Abstract
Transmission characteristics of PCV2 have been compared between vaccinated and non-vaccinated pigs in experimental conditions. Twenty-four Specific Pathogen Free (SPF) piglets, vaccinated against PCV2 at 3weeks of age (PCV2a recombinant CAP protein-based vaccine), were inoculated at 15days post-vaccination with a PCV2b inoculum (6⋅10(5) TCID50), and put in contact with 24 vaccinated SPF piglets during 42days post-inoculation. Those piglets were shared in six replicates of a contact trial involving 4 inoculated piglets mingled with 4 susceptible SPF piglets. Two replicates of a similar contact trial were made with non-vaccinated pigs. Non vaccinated animals received a placebo at vaccination time and were inoculated the same way and at the same time as the vaccinated group. All the animals were monitored twice weekly using quantitative real-time PCR and ELISA for serology until 42days post-inoculation. The frequency of infection and the PCV2 genome load in sera of the vaccinated pigs were significantly reduced compared to the non-vaccinated animals. The duration of infectiousness was significantly different between vaccinated and non-vaccinated groups (16.6days [14.7;18.4] and 26.6days [22.9;30.4] respectively). The transmission rate was also considerably decreased in vaccinated pigs (β=0.09 [0.05-0.14] compared to β=0.19 [0.11-0.32] in non-vaccinated pigs). This led to an estimated reproduction ratio of 1.5 [95% CI 0.8 - 2.2] in vaccinated animals versus 5.1 [95% CI 2.5 - 8.2] in non-vaccinated pigs when merging data of this experiment with previous trials carried out in same conditions.
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Affiliation(s)
- N Rose
- Anses, Laboratoire de Ploufragan-Plouzané, BP 53, 22440 Ploufragan, France; Université Bretagne Loire, Rennes, France.
| | - M Andraud
- Anses, Laboratoire de Ploufragan-Plouzané, BP 53, 22440 Ploufragan, France; Université Bretagne Loire, Rennes, France
| | - L Bigault
- Anses, Laboratoire de Ploufragan-Plouzané, BP 53, 22440 Ploufragan, France; Université Bretagne Loire, Rennes, France
| | - A Jestin
- Anses, Laboratoire de Ploufragan-Plouzané, BP 53, 22440 Ploufragan, France; Université Bretagne Loire, Rennes, France
| | - B Grasland
- Anses, Laboratoire de Ploufragan-Plouzané, BP 53, 22440 Ploufragan, France; Université Bretagne Loire, Rennes, France
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Dieste-Pérez L, Frankena K, Blasco JM, Muñoz PM, de Jong MCM. Efficacy of antibiotic treatment and test-based culling strategies for eradicating brucellosis in commercial swine herds. Prev Vet Med 2016; 126:105-10. [PMID: 26899897 DOI: 10.1016/j.prevetmed.2016.01.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 01/25/2016] [Accepted: 01/31/2016] [Indexed: 11/27/2022]
Abstract
Swine brucellosis caused by Brucella suis biovar 2 is an emerging disease in continental Europe. Without effective vaccines being available, the European Food Safety Authority (EFSA) recommends the full depopulation of infected herds as the only strategy to eradicate B. suis outbreaks. Using data collected from 8 herds suffering natural swine brucellosis outbreaks, we assessed the efficacy of four control strategies: (i) oxytetracycline treatment only, as a default scenario, (ii) oxytetracycline treatment combined with skin testing and removal of positive animals, (iii) oxytetracycline treatment combined with serological testing (Rose Bengal test-RBT-and indirect ELISA -iELISA-) and removal of seropositive animals and (iv) oxytetracycline treatment combined with both serological (RBT/iELISA) and skin testing and removal of positive animals. A Susceptible-Infectious-Removal model was used to estimate the reproduction ratio (R) for each strategy. According to this model, the oxytetracycline treatment alone was not effective enough to eradicate the infection. However, this antibiotic treatment combined with diagnostic testing at 4-monthly intervals plus immediate removal of positive animals showed to be effective to eradicate brucellosis independent of the diagnostic test strategy used in an acceptable time interval (1-2 years), depending on the initial number of infected animals.
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Affiliation(s)
- L Dieste-Pérez
- Animal Health Department, IA2 CITA-Universidad de Zaragoza, Av. Montañana 930, 50059 Zaragoza, Spain; Department of Farm Animal Health, Utrecht University, Faculty of Veterinary Medicine, Yalelaan 7, 3584 CL Utrecht, The Netherlands.
| | - K Frankena
- Quantitative Veterinary Epidemiology Group, Wageningen University, P.O. Box 338, 6700 AH Wageningen, The Netherlands
| | - J M Blasco
- Animal Health Department, IA2 CITA-Universidad de Zaragoza, Av. Montañana 930, 50059 Zaragoza, Spain
| | - P M Muñoz
- Animal Health Department, IA2 CITA-Universidad de Zaragoza, Av. Montañana 930, 50059 Zaragoza, Spain
| | - M C M de Jong
- Quantitative Veterinary Epidemiology Group, Wageningen University, P.O. Box 338, 6700 AH Wageningen, The Netherlands
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34
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Roos LR, Fano E, Homwong N, Payne B, Pieters M. A model to investigate the optimal seeder-to-naïve ratio for successful natural Mycoplasma hyopneumoniae gilt exposure prior to entering the breeding herd. Vet Microbiol 2016; 184:51-8. [DOI: 10.1016/j.vetmic.2016.01.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 01/01/2016] [Accepted: 01/06/2016] [Indexed: 10/22/2022]
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Anche MT, Bijma P, De Jong MCM. Genetic analysis of infectious diseases: estimating gene effects for susceptibility and infectivity. Genet Sel Evol 2015; 47:85. [PMID: 26537023 PMCID: PMC4634202 DOI: 10.1186/s12711-015-0163-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 10/16/2015] [Indexed: 12/02/2022] Open
Abstract
Background Genetic selection of livestock against infectious diseases can complement existing interventions to control infectious diseases. Most genetic approaches that aim at reducing disease prevalence assume that individual disease status (infected/not-infected) is solely a function of its susceptibility to a particular pathogen. However, individual infectivity also affects the risk and prevalence of an infection in a population. Variation in susceptibility and infectivity between hosts affects transmission of an infection in the population, which is usually measured by the value of the basic reproduction ratio R0. R0 is an important epidemiological parameter that determines the risk and prevalence of infectious diseases. An individual’s breeding value for R0 is a function of its genes that influence both susceptibility and infectivity. Thus, to estimate the effects of genes on R0, we need to estimate the effects of genes on individual susceptibility and infectivity. To that end, we developed a generalized linear model (GLM) to estimate relative effects of genes for susceptibility and infectivity. A simulation was performed to investigate bias and precision of the estimates, the effect of R0, the size of the effects of genes for susceptibility and infectivity, and relatedness among group mates on bias and precision. We considered two bi-allelic loci that affect, respectively, the individuals’ susceptibility only and individuals’ infectivity only. Results A GLM with complementary log–log link function can be used to estimate the relative effects of genes on the individual’s susceptibility and infectivity. The model was developed from an equation that describes the probability of an individual to become infected as a function of its own susceptibility genotype and infectivity genotypes of all its infected group mates. Results show that bias is smaller when R0 ranges approximately from 1.8 to 3.1 and relatedness among group mates is higher. With larger effects, both absolute and relative standard deviations become clearly smaller, but the relative bias remains the same. Conclusions We developed a GLM to estimate the relative effect of genes that affect individual susceptibility and infectivity. This model can be used in genome-wide association studies that aim at identifying genes that influence the prevalence of infectious diseases.
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Affiliation(s)
- Mahlet T Anche
- Animal Breeding and Genomics Centre, Wageningen University, 6700 AH, Wageningen, The Netherlands. .,Quantitative Veterinary Epidemiology Group, Wageningen University, 6700 AH, Wageningen, The Netherlands.
| | - P Bijma
- Animal Breeding and Genomics Centre, Wageningen University, 6700 AH, Wageningen, The Netherlands.
| | - Mart C M De Jong
- Quantitative Veterinary Epidemiology Group, Wageningen University, 6700 AH, Wageningen, The Netherlands.
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Wang G, Kang S, Yin Z, Jia RY, Lai X, Zhou X, Liang XX, Li LX, Zou YF, Lv C, He CL, Ye G, Yin LZ, Jing B. Therapeutic effect of Chinese patent medicine "Wuhuanghu" on porcine infectious pleuropneumonia and its acute and subchronic toxicity as well as evaluation of safety pharmacology. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2015; 40:388-396. [PMID: 26245812 DOI: 10.1016/j.etap.2015.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 07/02/2015] [Accepted: 07/08/2015] [Indexed: 06/04/2023]
Abstract
Chinese patent medicines play an important role in veterinary clinical use. The aim of this study is to research the anti-infection effect of Chinese patent medicine "Wuhuanghu" for the treatment of porcine infectious pleuropneumonia and to evaluate the safety of "Wuhuanghu" in order to provide a comprehensive understanding of its toxicity. The anti-infection results showed that the treatment with "Wuhuanghu" could significantly inhibit pneumonia and decrement of the pneumonia in high, medium and low doses of "Wuhuanghu" groups were 70.97%, 61.29% and 58.06% respectively. The acute toxicity test showed that rats in the highest group (5000mg/kg) had no death and no abnormal response, suggesting the LD50 of "Wuhuanghu" was more than 5000mg/kg. The subchronic toxicity study showed that hematology indexes in all groups had no obvious differences; blood biochemical index, only albumin and total cholesterol in middle and low doses of "Wuhuanghu" groups were significantly decreased when compared with control group. The clinical pathology showed that the target organ of "Wuhuanghu" was liver. The safety pharmacology study indicated that "Wuhuanghu" had no side effects on rats. In conclusion, "Wuhuanghu" has therapeutic and protective effects to porcine infectious pleuropneumonia in a dose-dependent manner and "Wuhuanghu" is a safe veterinary medicine.
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Affiliation(s)
- Guangxi Wang
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Shuai Kang
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Zhongqiong Yin
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Ren-Yong Jia
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Xin Lai
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Xun Zhou
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Xiao-Xia Liang
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Li-Xia Li
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Yuan-Feng Zou
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Cheng Lv
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Chang-Liang He
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Gang Ye
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Li-Zi Yin
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Bo Jing
- Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
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Abstract
The introduction into a naïve herd of animals sub-clinically infected with Actinobacillus pleuropneumoniae (App) is frequently the cause of clinical pleuropneumonia and the identification of such infected herds is a priority in the control of disease. Different serological tests for App have been developed and a number of these are routinely used. Some are species-specific whereas others identify more specifically the serotype/serogroup involved which requires updated information about important serotypes recovered from diseased pigs in a given area/country. Serotyping methods based on molecular techniques have been developed lately and are ready to be used by most diagnostic laboratories. When non-conclusive serological results are obtained, direct detection of App from tonsils is sometimes attempted. This review addresses different techniques and approaches used to monitor herds sub-clinically infected by this important pathogen.
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Affiliation(s)
- Marcelo Gottschalk
- Department of Pathology and Microbiology, Swine and Poultry Infectious Disease Center (CRIPA), Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Faculty of Veterinary Medicine, University of Montreal, St-Hyacinthe, Québec, Canada J2S 2M2.
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38
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Bravo de Rueda C, de Jong MCM, Eblé PL, Dekker A. Quantification of transmission of foot-and-mouth disease virus caused by an environment contaminated with secretions and excretions from infected calves. Vet Res 2015; 46:43. [PMID: 25928658 PMCID: PMC4404111 DOI: 10.1186/s13567-015-0156-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 01/30/2015] [Indexed: 11/10/2022] Open
Abstract
Foot-and-mouth disease virus (FMDV) infected animals can contaminate the environment with their secretions and excretions. To quantify the contribution of a contaminated environment to the transmission of FMDV, this study used calves that were not vaccinated and calves that were vaccinated 1 week prior to inoculation with the virus in direct and indirect contact experiments. In direct contact experiments, contact calves were exposed to inoculated calves in the same room. In indirect contact experiments, contact calves were housed in rooms that previously had held inoculated calves for three days (either from 0 to 3 or from 3 to 6 days post inoculation). Secretions and excretions from all calves were tested for the presence of FMDV by virus isolation; the results were used to quantify FMDV transmission. This was done using a generalized linear model based on a 2 route (2R, i.e. direct contact and environment) SIR model that included information on FMDV survival in the environment. The study shows that roughly 44% of transmission occurs via the environment, as indicated by the reproduction ratio R0(2R)environment that equalled 2.0, whereas the sum of R0(2R)contact and R0(2R)environment equalled 4.6. Because vaccination 1 week prior to inoculation of the calves conferred protective immunity against FMDV infection, no transmission rate parameters could be estimated from the experiments with vaccinated calves. We conclude that a contaminated environment contributes considerably to the transmission of FMDV therefore that hygiene measures can play a crucial role in FMD control.
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Affiliation(s)
- Carla Bravo de Rueda
- Central Veterinary Institute (CVI), part of Wageningen UR, P.O. Box 65, 8200 AB, Lelystad, The Netherlands. .,Department Quantitative Veterinary Epidemiology, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, The Netherlands.
| | - Mart C M de Jong
- Department Quantitative Veterinary Epidemiology, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, The Netherlands.
| | - Phaedra L Eblé
- Central Veterinary Institute (CVI), part of Wageningen UR, P.O. Box 65, 8200 AB, Lelystad, The Netherlands.
| | - Aldo Dekker
- Central Veterinary Institute (CVI), part of Wageningen UR, P.O. Box 65, 8200 AB, Lelystad, The Netherlands.
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Rose N, Renson P, Andraud M, Paboeuf F, Le Potier MF, Bourry O. Porcine reproductive and respiratory syndrome virus (PRRSv) modified-live vaccine reduces virus transmission in experimental conditions. Vaccine 2015; 33:2493-9. [PMID: 25820061 DOI: 10.1016/j.vaccine.2015.03.040] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/12/2015] [Indexed: 10/23/2022]
Abstract
Some vaccination strategies have shown good results in reducing the clinical outcomes of PRRS. Nevertheless the effect of vaccines on viral transmission is poorly described, so we aimed to fill this gap with the present study. Twelve Specific Pathogen Free (SPF) piglets, vaccinated against PRRSv at 3 weeks of age (Porcilis PRRS ID(®), MSD), were inoculated at 31 days post-vaccination with a heterologous genogroup 1.1 strain, and put in contact with 12 vaccinated piglets during 49 days. The same protocol was carried out simultaneously with SPF non-vaccinated piglets. Piglets were monitored individually for clinical symptoms on a daily basis and individual blood samples were taken twice a week. In inoculated piglets, the genome viral load specific to the inoculated strain was reduced and viraemia shortened in vaccinated piglets (28 days versus 38 days in non vaccinated piglets). In contact pigs, the challenge strain was detected in the serum of only one vaccinated piglet whereas it was detected in all contact non-vaccinated piglets. Transmission parameters were estimated by a Bayesian analysis of transmission data in the two groups. The estimated transmission rate was 10-times lower in vaccinated than in non-vaccinated piglets and the duration of infectiousness was reduced, leading to a reproduction ratio R significantly lower (0.30 [0.05-0.96] versus 5.42 [2.94-9.04] in non vaccinated piglets). Hence, in our experimental conditions, vaccination was able to decrease considerably PRRSv spread. A complementary evaluation in field conditions would be required to identify circumstances associated with infection control failures that can be observed in pig farms.
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Affiliation(s)
- N Rose
- Anses-Laboratoire de Ploufragan-Plouzané, BP 53, 22440 Ploufragan, France; Université Européenne de Bretagne, Rennes, France.
| | - P Renson
- Anses-Laboratoire de Ploufragan-Plouzané, BP 53, 22440 Ploufragan, France; Université Européenne de Bretagne, Rennes, France
| | - M Andraud
- Anses-Laboratoire de Ploufragan-Plouzané, BP 53, 22440 Ploufragan, France; Université Européenne de Bretagne, Rennes, France
| | - F Paboeuf
- Anses-Laboratoire de Ploufragan-Plouzané, BP 53, 22440 Ploufragan, France; Université Européenne de Bretagne, Rennes, France
| | - M F Le Potier
- Anses-Laboratoire de Ploufragan-Plouzané, BP 53, 22440 Ploufragan, France; Université Européenne de Bretagne, Rennes, France
| | - O Bourry
- Anses-Laboratoire de Ploufragan-Plouzané, BP 53, 22440 Ploufragan, France; Université Européenne de Bretagne, Rennes, France
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Simulation study of the mechanisms underlying outbreaks of clinical disease caused by Actinobacillus pleuropneumoniae in finishing pigs. Vet J 2014; 202:99-105. [DOI: 10.1016/j.tvjl.2014.06.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 06/16/2014] [Accepted: 06/18/2014] [Indexed: 01/17/2023]
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41
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Tobias TJ, Bouma A, van den Broek J, van Nes A, Daemen AJJM, Wagenaar JA, Stegeman JA, Klinkenberg D. Transmission of Actinobacillus pleuropneumoniae among weaned piglets on endemically infected farms. Prev Vet Med 2014; 117:207-14. [PMID: 25156946 DOI: 10.1016/j.prevetmed.2014.07.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 07/25/2014] [Accepted: 07/29/2014] [Indexed: 10/24/2022]
Abstract
Clinical outbreaks due to Actinobacillus pleuropneumoniae occur recurrently, despite the wide-scale use of antimicrobials or vaccination. Therefore, new approaches for the prevention and control of these outbreaks are necessary. For the development of alternative measures, more insight into the transmission of the bacterium on farms is necessary. The aim of this cohort study was to quantify transmission of A. pleuropneumoniae amongst weaned piglets on farms. We investigated three possible transmission routes: (i) indirect transmission by infected piglets within the same compartment, (ii) transmission by infected pigs in adjacent pens and (iii) transmission by direct contact within pens. Additionally, we evaluated the effect of independent litter characteristics on the probability of infection. Two farms participated in our study. Serum and tonsil brush samples were collected from sows pre-farrowing. Serum was analysed for antibodies against Apx toxins and Omp. Subsequently, tonsil brush samples were collected from all piglets from these dams (N=542) in three cohorts, 3 days before weaning and 6 weeks later. Tonsil samples were analysed by qPCR for the presence of the apxIVA gene of A. pleuropneumoniae. Before weaning, 25% of the piglets tested positive; 6 weeks later 47% tested positive. Regression and stochastic transmission models were used to assess the contribution of each of the three transmission routes and to estimate transmission rates. Transmission between piglets in adjacent pens did not differ significantly from that between non-adjacent pens. The transmission rate across pens was estimated to be 0.0058 day(-1) (95% CI: 0.0030-0.010), whereas the transmission rate within pens was ten times higher 0.059 day(-1) (95% CI: 0.048-0.072). Subsequently, the effects of parity and serological response of the dam and litter age at weaning on the probability of infection of pigs were evaluated by including these into the regression model. A higher dam ApxII antibody level was associated with a lower probability of infection of the pig after weaning; age at weaning was associated with a higher probability of infection of the pig after weaning. Finally, transmission rate estimates were used in a scenario study in which the litters within a compartment were mixed across pens at weaning instead of raising litter mates together in a pen. The results showed that the proportion of infected piglets increased to 69% if litters were mixed at weaning, indicating that farm management measures may affect spread of A. pleuropneumoniae.
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Affiliation(s)
- T J Tobias
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands.
| | - A Bouma
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands
| | - J van den Broek
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands
| | - A van Nes
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands
| | - A J J M Daemen
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands
| | - J A Wagenaar
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands; Central Veterinary Institute of Wageningen UR, PO Box 65, 8200 AB Lelystad, The Netherlands
| | - J A Stegeman
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands
| | - D Klinkenberg
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands
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42
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Tobias T, Klinkenberg D, Bouma A, van den Broek J, Daemen A, Wagenaar J, Stegeman J. A cohort study on Actinobacillus pleuropneumoniae colonisation in suckling piglets. Prev Vet Med 2014; 114:223-30. [DOI: 10.1016/j.prevetmed.2014.02.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 02/05/2014] [Accepted: 02/18/2014] [Indexed: 10/25/2022]
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43
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Correia-Gomes C, Economou T, Bailey T, Brazdil P, Alban L, Niza-Ribeiro J. Transmission parameters estimated for Salmonella typhimurium in swine using susceptible-infectious-resistant models and a Bayesian approach. BMC Vet Res 2014; 10:101. [PMID: 24774444 PMCID: PMC4030535 DOI: 10.1186/1746-6148-10-101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 04/16/2014] [Indexed: 11/29/2022] Open
Abstract
Background Transmission models can aid understanding of disease dynamics and are useful in testing the efficiency of control measures. The aim of this study was to formulate an appropriate stochastic Susceptible-Infectious-Resistant/Carrier (SIR) model for Salmonella Typhimurium in pigs and thus estimate the transmission parameters between states. Results The transmission parameters were estimated using data from a longitudinal study of three Danish farrow-to-finish pig herds known to be infected. A Bayesian model framework was proposed, which comprised Binomial components for the transition from susceptible to infectious and from infectious to carrier; and a Poisson component for carrier to infectious. Cohort random effects were incorporated into these models to allow for unobserved cohort-specific variables as well as unobserved sources of transmission, thus enabling a more realistic estimation of the transmission parameters. In the case of the transition from susceptible to infectious, the cohort random effects were also time varying. The number of infectious pigs not detected by the parallel testing was treated as unknown, and the probability of non-detection was estimated using information about the sensitivity and specificity of the bacteriological and serological tests. The estimate of the transmission rate from susceptible to infectious was 0.33 [0.06, 1.52], from infectious to carrier was 0.18 [0.14, 0.23] and from carrier to infectious was 0.01 [0.0001, 0.04]. The estimate for the basic reproduction ration (R0) was 1.91 [0.78, 5.24]. The probability of non-detection was estimated to be 0.18 [0.12, 0.25]. Conclusions The proposed framework for stochastic SIR models was successfully implemented to estimate transmission rate parameters for Salmonella Typhimurium in swine field data. R0 was 1.91, implying that there was dissemination of the infection within pigs of the same cohort. There was significant temporal-cohort variability, especially at the susceptible to infectious stage. The model adequately fitted the data, allowing for both observed and unobserved sources of uncertainty (cohort effects, diagnostic test sensitivity), so leading to more reliable estimates of transmission parameters.
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Affiliation(s)
- Carla Correia-Gomes
- ICBAS-UP - Department of Population Studies, Instituto de Ciências Biomédicas Abel Salazar - Universidade do Porto, Rua de Jorge Viterbo Ferreira, n°228, 4050-313 Porto, Portugal.
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Lipschutz-Powell D, Woolliams JA, Doeschl-Wilson AB. A unifying theory for genetic epidemiological analysis of binary disease data. Genet Sel Evol 2014; 46:15. [PMID: 24552188 PMCID: PMC3996085 DOI: 10.1186/1297-9686-46-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 11/23/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genetic selection for host resistance offers a desirable complement to chemical treatment to control infectious disease in livestock. Quantitative genetics disease data frequently originate from field studies and are often binary. However, current methods to analyse binary disease data fail to take infection dynamics into account. Moreover, genetic analyses tend to focus on host susceptibility, ignoring potential variation in infectiousness, i.e. the ability of a host to transmit the infection. This stands in contrast to epidemiological studies, which reveal that variation in infectiousness plays an important role in the progression and severity of epidemics. In this study, we aim at filling this gap by deriving an expression for the probability of becoming infected that incorporates infection dynamics and is an explicit function of both host susceptibility and infectiousness. We then validate this expression according to epidemiological theory and by simulating epidemiological scenarios, and explore implications of integrating this expression into genetic analyses. RESULTS Our simulations show that the derived expression is valid for a range of stochastic genetic-epidemiological scenarios. In the particular case of variation in susceptibility only, the expression can be incorporated into conventional quantitative genetic analyses using a complementary log-log link function (rather than probit or logit). Similarly, if there is moderate variation in both susceptibility and infectiousness, it is possible to use a logarithmic link function, combined with an indirect genetic effects model. However, in the presence of highly infectious individuals, i.e. super-spreaders, the use of any model that is linear in susceptibility and infectiousness causes biased estimates. Thus, in order to identify super-spreaders, novel analytical methods using our derived expression are required. CONCLUSIONS We have derived a genetic-epidemiological function for quantitative genetic analyses of binary infectious disease data, which, unlike current approaches, takes infection dynamics into account and allows for variation in host susceptibility and infectiousness.
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Affiliation(s)
- Debby Lipschutz-Powell
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - John A Woolliams
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Andrea B Doeschl-Wilson
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
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De Ridder L, Maes D, Dewulf J, Pasmans F, Boyen F, Haesebrouck F, Méroc E, Roels S, Leyman B, Butaye P, Van der Stede Y. Effect of a DIVA vaccine with and without in-feed use of coated calcium-butyrate on transmission of Salmonella Typhimurium in pigs. BMC Vet Res 2013; 9:243. [PMID: 24304918 PMCID: PMC4235050 DOI: 10.1186/1746-6148-9-243] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 11/27/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND For satisfactory Salmonella control, good biosecurity along the pork production chain is crucial, although additional control measures on-farm need to be considered. This study evaluated the effect of two potential control measures against the spread of Salmonella Typhimurium via a transmission experiment with 56 piglets (3-15 weeks of age): two groups were orally vaccinated with 107 - 108 Colony Forming Units (CFU)/2 mL of a new attenuated Salmonella Typhimurium vaccine 'Salmoporc-∆rfaJ' with DIVA capacities (Differentiation between Infected and Vaccinated Animals) (n = 2x16); the feed of one group was additionally supplemented with coated calcium-butyrate salt. Two weeks post vaccination, four pigs per group were orally challenged with 107 CFU/2 mL of a Salmonella Typhimurium strain 112910a. Both groups were compared with a positive (challenged/untreated; n = 16) and negative (unchallenged/untreated; n = 8) control group. Until six weeks post challenge, blood, individual faecal and finally tissue samples were examined. Adjusted transmission ratios 'Ra' were estimated, based on the challenge strain isolation from faecal and/or tissue samples. RESULTS In both intervention groups, Ra values were lower compared to the positive control group, although these differences were not significant. In the combination group DIVA vaccine + coated butyrate, less non-challenged contact animals excreted Salmonella and less tissue samples were found Salmonella-positive in all pigs, when compared to the positive control group (P < 0.01). Seroconversion was detected in none of the vaccinated animals before challenge, when using a commercial lipopolysaccharide (LPS) ELISA targeting only Salmonella O-antigens, deleted in this vaccine. This was in contrast with an in-house whole-cell ELISA testing for various Salmonella antigens, in which Salmonella-specific antibodies were found pre-challenge in the serum of the vaccinated pigs. CONCLUSIONS Both interventions showed a limited, non-significant reduction of Salmonella transmission between piglets. They may have applications towards Salmonella control and surveillance. Firstly, the number of Salmonella excreting contact pigs was significantly lower in the group where vaccination was combined with coated calcium-butyrate salt in the feed; secondly, the new vaccine confirmed its DIVA capacity. Therefore, these interventions merit further research with larger sample sizes, to optimize their use for Salmonella programmes.
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Affiliation(s)
- Lotte De Ridder
- Unit of Co-ordination in Veterinary Diagnostics-Epidemiology and Risk Analysis, CODA-CERVA, Groeselenberg 99, 1180 Ukkel, Belgium.
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46
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An experimental model to analyse the risk of introduction of a duck-originated H5 low-pathogenic avian influenza virus in poultry through close contact and contaminative transmission. Epidemiol Infect 2013; 142:1836-47. [PMID: 24252718 DOI: 10.1017/s0950268813002793] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aquatic wild birds are often carriers of low-pathogenic avian influenza viruses (LPAIVs). If H5 and H7 LPAIVs are transmitted to poultry and have the opportunity to circulate, a highly pathogenic AIV may arise. Contact with aquatic wild birds is one of the most important ways in which these LPAIVs can be introduced into poultry flocks. In this study, the transmissibility of a duck-originated H5 LPAIV between ducks and chickens was analysed in a series of animal experiments, using different transmission routes. Results indicate that the outcome of virus intake by chickens exposed to infectious ducks depends on the way the virus is presented. Faecally contaminated drinking water proved to be the most efficient route by which the virus can be transmitted to chickens. The results from this study also suggest that some duck-originated H5 LPAIVs may be introduced to poultry but do not have the potential to become established in poultry populations.
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47
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De Ridder L, Maes D, Dewulf J, Pasmans F, Boyen F, Haesebrouck F, Méroc E, Butaye P, Van der Stede Y. Evaluation of three intervention strategies to reduce the transmission of Salmonella Typhimurium in pigs. Vet J 2013; 197:613-8. [DOI: 10.1016/j.tvjl.2013.03.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 02/08/2013] [Accepted: 03/21/2013] [Indexed: 02/01/2023]
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48
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Crombé F, Argudín MA, Vanderhaeghen W, Hermans K, Haesebrouck F, Butaye P. Transmission Dynamics of Methicillin-Resistant Staphylococcus aureus in Pigs. Front Microbiol 2013; 4:57. [PMID: 23518663 PMCID: PMC3602589 DOI: 10.3389/fmicb.2013.00057] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Accepted: 02/28/2013] [Indexed: 12/14/2022] Open
Abstract
From the mid-2000s on, numerous studies have shown that methicillin-resistant Staphylococcus aureus (MRSA), renowned as human pathogen, has a reservoir in pigs and other livestock. In Europe and North America, clonal complex (CC) 398 appears to be the predominant lineage involved. Especially worrisome is its capacity to contaminate humans in close contact with affected animals. Indeed, the typical multi-resistant phenotype of MRSA CC398 and its observed ability of easily acquiring genetic material suggests that MRSA CC398 strains with an increased virulence potential may emerge, for which few therapeutic options would remain. This questions the need to implement interventions to control the presence and spread of MRSA CC398 among pigs. MRSA CC398 shows a high but not fully understood transmission potential in the pig population and is able to persist within that population. Although direct contact is probably the main route for MRSA transmission between pigs, also environmental contamination, the presence of other livestock, the herd size, and farm management are factors that may be involved in the dissemination of MRSA CC398. The current review aims at summarizing the research that has so far been done on the transmission dynamics and risk factors for introduction and persistence of MRSA CC398 in farms.
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Affiliation(s)
- Florence Crombé
- Department of Bacterial Diseases, Veterinary and Agrochemical Research CentreBrussels, Belgium
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent UniversityGhent, Belgium
| | - M. Angeles Argudín
- Department of Bacterial Diseases, Veterinary and Agrochemical Research CentreBrussels, Belgium
| | - Wannes Vanderhaeghen
- Department of Bacterial Diseases, Veterinary and Agrochemical Research CentreBrussels, Belgium
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent UniversityGhent, Belgium
| | - Katleen Hermans
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent UniversityGhent, Belgium
| | - Freddy Haesebrouck
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent UniversityGhent, Belgium
| | - Patrick Butaye
- Department of Bacterial Diseases, Veterinary and Agrochemical Research CentreBrussels, Belgium
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent UniversityGhent, Belgium
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Association between transmission rate and disease severity for Actinobacillus pleuropneumoniae infection in pigs. Vet Res 2013; 44:2. [PMID: 23311865 PMCID: PMC3574036 DOI: 10.1186/1297-9716-44-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 01/03/2013] [Indexed: 11/22/2022] Open
Abstract
A better understanding of the variation in infectivity and its relation with clinical signs may help to improve measures to control and prevent (clinical) outbreaks of diseases. Here we investigated the role of disease severity on infectivity and transmission of Actinobacillus pleuropneumoniae, a bacterium causing respiratory problems in pig farms. We carried out transmission experiments with 10 pairs of caesarean-derived, colostrum-deprived pigs. In each pair, one pig was inoculated intranasally with 5 × 106 CFUs of A. pleuropneumoniae strain 1536 and housed together with a contact pig. Clinical signs were scored and the course of infection was observed by bacterial examination and qPCR analysis of tonsillar brush and nasal swab samples. In 6 out of 10 pairs transmission to contact pigs was observed, but disease scores in contact infected pigs were low compared to the score in inoculated pigs. Whereas disease score was positively associated with bacterial load in inoculated pigs and bacterial load with the transmission rate, the disease score had a negative association with transmission. These findings indicate that in pigs with equal bacterial load, those with higher clinical scores transmit A. pleuropneumoniae less efficiently. Finally, the correlation between disease score in inoculated pigs and in positive contact pigs was low. Although translation of experimental work towards farm level has limitations, our results suggest that clinical outbreaks of A. pleuropneumoniae are unlikely to be caused only by spread of the pathogen by clinically diseased pigs, but may rather be the result of development of clinical signs in already infected pigs.
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50
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Allerson M, Deen J, Detmer SE, Gramer MR, Joo HS, Romagosa A, Torremorell M. The impact of maternally derived immunity on influenza A virus transmission in neonatal pig populations. Vaccine 2013; 31:500-5. [PMID: 23174202 PMCID: PMC3534892 DOI: 10.1016/j.vaccine.2012.11.023] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 11/02/2012] [Accepted: 11/08/2012] [Indexed: 11/22/2022]
Abstract
The commonality of influenza A virus (IAV) exposure and vaccination on swine farms in the United States ensures that the majority of neonatal pigs will have some degree of maternal immunity to IAV. The influence of maternal immunity on IAV transmission in neonatal pig populations will impact virus prevalence and infection dynamics across pig populations. The main objective of this study was to assess the impact of maternally derived immunity on IAV transmission in an experimental setting. Neonatal pigs suckled colostrum and derived maternal (passive) immunity from sows in one of three treatment groups: (a) non-vaccinated control (CTRL) or vaccinated with (b) homologous (PASSV-HOM) or (c) heterologous (PASSV-HET) inactivated experimental IAV vaccines. Sentinel neonatal pigs derived from the groups above were challenged with IAV via direct contact with an experimentally infected pig (seeder pig) and monitored for IAV infection daily via nasal swab sampling. A susceptible-infectious-recovered (SIR) experimental model was used to obtain and estimate transmission parameters in each treatment group via a generalized linear model. All sentinel pigs in the CTRL (30/30) and PASSV-HET (30/30) groups were infected with IAV following contact with the seeder pigs and the reproduction ratio estimates (95% confidence interval) were 10.4 (6.6-15.8) and 7.1 (4.2-11.3), respectively. In contrast, 1/20 sentinel pigs in the PASSV-HOM group was infected following contact with the seeder pigs and the reproduction ratio estimate was significantly lower compared to the CTRL and PASSV-HET groups at 0.8 (0.1-3.7). Under the conditions of this study, IAV transmission was reduced in neonatal pigs with homologous maternal immunity compared to seronegative neonatal pigs and pigs with heterologous maternal immunity as defined in this study. This study provides estimates for IAV transmission in pigs with differing types of maternal immunity which may describe the influence of maternal immunity on IAV prevalence and infection dynamics in pig populations.
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Affiliation(s)
- Matt Allerson
- College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108, USA
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