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Ly A, Kirkeby C, Sergeant ESG, Plain KM, Smith M, Dhand NK. Comparison of the current abattoir surveillance system for detection of paratuberculosis in Australian sheep with quantitative PCR tissue strategies using simulation modelling. Prev Vet Med 2021; 196:105495. [PMID: 34547663 DOI: 10.1016/j.prevetmed.2021.105495] [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: 07/07/2021] [Revised: 09/08/2021] [Accepted: 09/13/2021] [Indexed: 10/20/2022]
Abstract
Abattoir surveillance for Johne's disease monitoring in Australia has provided valuable feedback to producers about their flock's disease status since its commencement in 1999. The current surveillance system relies on the identification of gross lesions in sheep carcases at an abattoir, followed by sampling and histopathology testing. This manual inspection system has not been adapted to meet the changing disease situation, as infection prevalence levels have declined over time due to vaccination. This simulation study compares the current system with two alternative approaches utilising a validated quantitative (q)PCR method for the detection of Mycobacterium avium subsp. paratuberculosis in tissues, with random systematic sampling either alone or in conjunction with sampling of a single carcass presenting gross lesions. Consigned sheep were randomly simulated as either infected or uninfected according to defined prevalence levels of infection, with varying histopathological lesion severity and the presence or absence of gross lesions. These sheep were then allocated into multiple 'lines' (group of sheep slaughtered together) within each consignment, with each line subjected to testing with the three sampling strategies for the estimation of line and flock (consignment) sensitivity. The line sensitivity described the proportion of infected lines that tested positive, whereas the flock sensitivity was the proportion of consignments from the simulated infected flocks that had one or more lines test positive for paratuberculosis infection. The tissue qPCR strategy with gross lesion detection achieved marginally higher line sensitivity than the current abattoir surveillance strategy. The simulation of unvaccinated infected flocks with low to moderate prevalence levels demonstrated similar flock sensitivity for all three sampling models. However, the current strategy had very low line sensitivity for the simulated vaccinated infected flocks when the infection prevalence level was <2%. There were substantial differences in flock sensitivity between the two tissue qPCR approaches and the current abattoir surveillance strategy for vaccinated infected flocks, whereas, only marginal differences in flock sensitivity were evident between the two tissue qPCR models. Our results demonstrate that the current strategy is not effective at identifying infected animals at very low infection prevalence levels. The tissue qPCR approach investigated in this study is better as it removes the reliance on meat inspectors to identify gross lesions and can also assist in identifying flocks that have subclinical infected sheep not displaying gross lesions. Therefore, the sheep industry may benefit from incorporating tissue qPCR for Johne's disease surveillance, however the logistics and costs of conducting this type of testing would need to be considered prior to implementing any changes.
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Affiliation(s)
- Anna Ly
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camden, NSW, Australia
| | - Carsten Kirkeby
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | | | - Karren M Plain
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camden, NSW, Australia
| | - Melanie Smith
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camden, NSW, Australia
| | - Navneet K Dhand
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camden, NSW, Australia.
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Pourmahdi Borujeni M, Haji Hajikolaei MR, Ghorbanpoor M, Elhaei Sahar H, Bagheri S, Roveyshedzadeh S. Comparison of Mycobacterium avium subsp. paratuberculosis infection in cattle, sheep and goats in the Khuzestan Province of Iran: Results of a preliminary survey. Vet Med Sci 2021; 7:1970-1979. [PMID: 34228398 PMCID: PMC8464266 DOI: 10.1002/vms3.559] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background Paratuberculosis or Johne's disease, the chronic infectious granulomatous enteritis of ruminants, is a worldwide infection, which is caused by Mycobacterium avium subsp. paratuberculosis (MAP). The most common symptoms of this disease in cattle are loss of milk production, weight loss and diarrhoea, whereas in sheep and goats, the symptoms are emaciation, anorexia and severe disability. Objectives The aim of this study was to compare the seroprevalence of MAP in cattle, sheep and goats in the southwest of Iran. Methods Blood samples were randomly collected from 530 cattle, 568 sheep and 368 goats in southwest of Iran. Sera were tested by a commercial ELISA kit (ID vet; ID Screen® Paratuberculosis Indirect) for detection of antibodies of MAP. Results Overall apparent and true seroprevalence rate of MAP was 6.00% (95% CI: 4.90%–7.30%) and 13.25% (95% CI: 11.55%– 14.95%). Apparent and true seroprevalence of MAP, respectively, was 4.34% (95% CI: 3.88%–6.46%) and 9.19% (95% CI: 6.98%–11.98%) in cattle, 6.87% (95% CI: 5.05%–9.27%) and 15.37% (95% CI: 12.60%–16.60%) in sheep and 7.07% (95% CI: 4.82%–10.18%) and 15.86% (95% CI: 12.41%–20.01%) in goats, respectively. As a result, there was no significant relationship between animal species and MAP infection. Moreover, multivariate logistic regression showed that the infection rate is not associated with age, gender and geographical location in cattle, sheep and goats (P > 0.05). Conclusion This study confirms that the seroprevalence of MAP is relatively considerable in the cattle, sheep and goats in the southwest of Iran, although in cattle, it is less than goats and sheep. Therefore, preventive and control measures should be considered by animal health authorities and meat and dairy processing units.
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Affiliation(s)
- Mahdi Pourmahdi Borujeni
- Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | | | - Masoud Ghorbanpoor
- Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Hamzeh Elhaei Sahar
- Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Saeed Bagheri
- Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Sanaz Roveyshedzadeh
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
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Using Omics Approaches in the Discovery of Biomarkers for Early Diagnosis of Johne's Disease in Sheep and Goats. Animals (Basel) 2021; 11:ani11071912. [PMID: 34199073 PMCID: PMC8300312 DOI: 10.3390/ani11071912] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/18/2021] [Accepted: 06/23/2021] [Indexed: 12/16/2022] Open
Abstract
Simple Summary Johne’s disease (JD) is caused by Mycobacterium avium subsp. paratuberculosis (MAP) and is an important and emerging problem in livestock. Most JD research has been carried out on cattle, but interest in the pathogenesis and diagnosis of this disease in sheep and goats is greatest in developing countries. Sheep and goats are also a relevant part of livestock production in Europe and Australia, and these species provide an excellent resource to study and better understand the mechanism of survival of MAP and gain insights into possible approaches to control this disease. This review gives an overview of the literature on paratuberculosis in sheep and goats, highlighting the immunological aspects and the potential for “omics” approaches to identify effective biomarkers for the early detection of infection. Abstract Johne’s disease (JD) is caused by Mycobacterium avium subsp. paratuberculosis (MAP) and is an important and emerging problem in livestock; therefore, its control and prevention is a priority to reduce economic losses and health risks. Most JD research has been carried out on cattle, but interest in the pathogenesis and diagnosis of this disease in sheep and goats is greatest in developing countries. Sheep and goats are also a relevant part of livestock production in Europe and Australia, and these species provide an excellent resource to study and better understand the mechanism of survival of MAP and gain insights into possible approaches to control this disease. This review gives an overview of the literature on paratuberculosis in sheep and goats, highlighting the immunological aspects and the potential for “omics” approaches to identify effective biomarkers for the early detection of infection. As JD has a long incubation period before the disease becomes evident, early diagnosis is important to control the spread of the disease.
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Links IJ, Denholm LJ, Evers M, Kingham LJ, Greenstein RJ. Is vaccination a viable method to control Johne's disease caused by Mycobacterium avium subsp. paratuberculosis? Data from 12 million ovine vaccinations and 7.6 million carcass examinations in New South Wales, Australia from 1999-2009. PLoS One 2021; 16:e0246411. [PMID: 34125838 PMCID: PMC8202914 DOI: 10.1371/journal.pone.0246411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 05/11/2021] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Mycobacterium avium subsp. paratuberculosis (MAP) causes Johne's disease (or paratuberculosis), a chronic wasting disease of ruminants and other animals resulting from granulomatous enteritis. There are increasing concerns that MAP is zoonotic. The prevalence of Johne's disease is increasing worldwide. In an attempt to control an epidemic of ovine Johne's disease (OJD) in New South Wales (NSW), a government/industry sponsored voluntary vaccination/on-farm management program commenced in 2000. We report herein an observational study of changes in disease prevalence as vaccination progressed, based on abattoir surveillance data for OJD from 1999 to 2009. We also discuss the epidemiological, policy, regulatory, research, economic and sociological elements that contributed to the development of a mature control program, whose aim was to halt the epidemic spread of OJD in a naïve sheep population. METHODS NSW was divided into areas of "High" (HPA), "Medium" (MPA) and "Low" (LPA) OJD prevalence. A killed whole cell vaccine (Gudair®) was administered to sheep from 2000 to 2009. Trained examiners evaluated the viscera of adult sheep carcasses at slaughter for gross evidence of OJD. MAP infection was confirmed by histopathology. PRINCIPAL FINDINGS From 2000-2009, 12 million vaccine doses were administered in NSW (91%; 10.9 million in the HPA). Many of the vaccinated flocks were suffering > 5% annual mortality in adult sheep, with some individual flocks with 10-15% losses attributable to OJD. A total of 7.6 million carcasses were examined (38%; 2.9 million from the HPA). Overall, 16% of slaughter consignments (sheep consigned to the abattoir from a single vendor) were positive for OJD, of which 94% were from the HPA. In the HPA, the percentage of animals with lesions attributable to OJD at slaughter fell progressively from 2.4% (10,406/432,860) at commencement of vaccination in 2000 to 0.8% (1,573/189,564) by 2009. Herd immunity from vaccination in the HPA was estimated at 70% by 2009, the target commonly espoused for an effective control program based on vaccination. This coincided with a progressive decrease in reports of clinical disease and mortalities in vaccinated flocks. SIGNIFICANCE We show a decrease in the prevalence of lesions attributable to OJD in NSW concomitant with initiation of voluntary vaccination, on-farm management plans, abattoir monitoring and feedback of animal prevalence data to sheep producers. We conclude that a target of ≤ 1% regional prevalence of OJD affected sheep at slaughter is achievable using these interventions.
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Affiliation(s)
- Ian J. Links
- Graham Centre for Agricultural Innovation (An alliance of Charles Sturt University and NSW Department of Primary Industries), Wagga Wagga, New South Wales, Australia
| | - Laurence J. Denholm
- Strategy and Delivery Group, NSW Department of Premier and Cabinet, Orange, New South Wales, Australia
| | - Marilyn Evers
- Formerly NSW Department of Primary Industries, Orange, New South Wales, Australia
| | - Lloyd J. Kingham
- NSW Department of Primary Industries, Orange, New South Wales, Australia
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Yaman Y, Aymaz R, Keleş M, Bay V, Ün C, Heaton MP. Association of TLR2 haplotypes encoding Q650 with reduced susceptibility to ovine Johne's disease in Turkish sheep. Sci Rep 2021; 11:7088. [PMID: 33782507 PMCID: PMC8007707 DOI: 10.1038/s41598-021-86605-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 03/18/2021] [Indexed: 02/06/2023] Open
Abstract
Ovine Johne’s disease (OJD) is caused by Mycobacterium avium subsp. paratuberculosis (MAP) and carries a potential zoonotic risk for humans. Selective breeding strategies for reduced OJD susceptibility would be welcome tools in disease eradication efforts, if available. The Toll-like receptor 2 gene (TLR2) plays an important signaling role in immune response to MAP, and missense variants are associated with mycobacterial infections in mammals. Our aim was to identify and evaluate ovine TLR2 missense variants for association with OJD in Turkish sheep. Eleven TLR2 missense variants and 17 haplotype configurations were identified in genomic sequences of 221 sheep from 61 globally-distributed breeds. The five most frequent haplotypes were tested for OJD association in 102 matched pairs of infected and uninfected ewes identified in 2257 Turkish sheep. Ewes with one or two copies of TLR2 haplotypes encoding glutamine (Q) at position 650 (Q650) in the Tir domain were 6.6-fold more likely to be uninfected compared to ewes with arginine (R650) at that position (CI95 = 2.6 to 16.9, p-value = 3.7 × 10–6). The protective TLR2 Q650 allele was present in at least 25% of breeds tested and thus may facilitate selective breeding for sheep with reduced susceptibility to OJD.
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Affiliation(s)
- Yalçın Yaman
- Department of Biometry and Genetics, Sheep Breeding and Research Institute, 10200, Bandırma, Balıkesir, Turkey.
| | - Ramazan Aymaz
- Department of Biometry and Genetics, Sheep Breeding and Research Institute, 10200, Bandırma, Balıkesir, Turkey
| | - Murat Keleş
- Department of Biometry and Genetics, Sheep Breeding and Research Institute, 10200, Bandırma, Balıkesir, Turkey
| | - Veysel Bay
- Department of Biometry and Genetics, Sheep Breeding and Research Institute, 10200, Bandırma, Balıkesir, Turkey
| | - Cemal Ün
- Department of Biology, Faculty of Science, Ege University, 35000, İzmir, Turkey
| | - Michael P Heaton
- USDA, ARS, U.S. Meat Animal Research Center, Clay Center, NE, 68933, USA
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Selim A, Abdelhady A, Abdelrahman A. Ovine Paratuberculosis: Seroprevalence and comparison of fecal culture and direct fecal PCR assay. Comp Immunol Microbiol Infect Dis 2020; 74:101526. [PMID: 32861473 DOI: 10.1016/j.cimid.2020.101526] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 07/21/2020] [Accepted: 08/04/2020] [Indexed: 12/01/2022]
Abstract
Johne's disease is chronic, incurable disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP). Most studies in Egypt focused on incidence of the disease in cattle but few studies were reported presence of antibodies against MAP in sheep. The present study determined the seroprevalence rate of MAP among sheep in four Governorates and assessed the associated risk factors to MAP-infection. The seroprevalence rate of MAP among sheep was non-significant varied between different Governorates, it was ranged between 3.75%-12.3%. The results revealed that the seroprevalence rate of the disease was significantly increased in diarrheic sheep (11 %, 95 %CI: 7.2-16.2) during spring (15 %, 95 %CI: 8.3-25) and summer (8%, 95 %CI: 4.13-13.8) seasons. Contrary, the age of sheep and contact with other ruminants like cattle or goats had non-significant effect of spreading of MAP-infection among sheep. The detection of MAP in feces of sheep was carried out using culture and PCR to determine the efficiency of both tests. The kappa test revealed good agreement between both tests for detection of MAP. The obtained finding confirms the presence of MAP among sheep in Egypt. So, the appropriate control measures should be taken to reduce spreading of the disease among sheep and reduce its economic losses.
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Affiliation(s)
- Abdelfattah Selim
- Department of Animal Medicine (Infectious Diseases), Faculty of Veterinary Medicine, Benha University, Egypt.
| | - Abdelhamed Abdelhady
- Department of Parasitology and Animal Diseases, National Research Center, Dokki, Giza, Egypt
| | - Amir Abdelrahman
- Animal Medicine Department (Infectious Diseases), Faculty of Veterinary Medicine, Alexandria University, Egypt
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Johansen MD, de Silva K, Plain KM, Begg DJ, Whittington RJ, Purdie AC. Sheep and cattle exposed to Mycobacterium avium subspecies paratuberculosis exhibit altered total serum cholesterol profiles during the early stages of infection. Vet Immunol Immunopathol 2018; 202:164-171. [PMID: 30078591 DOI: 10.1016/j.vetimm.2018.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 06/04/2018] [Accepted: 07/15/2018] [Indexed: 12/20/2022]
Abstract
Pathogenic mycobacteria such as Mycobacterium tuberculosis are capable of utilising cholesterol as a primary carbon-based energy source in vitro but there has been little research examining the significance of cholesterol in vivo. Johne's disease is a chronic enteric disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). This study sought to evaluate the levels of total serum cholesterol in the host following exposure to MAP. Blood samples were collected from both sheep and cattle prior to experimental challenge with MAP and at monthly intervals post-challenge. Total serum cholesterol levels in sheep challenged with MAP were significantly elevated at 9 weeks post-inoculation (wpi) in comparison to controls. When stratified based on disease outcome, there was no significant difference in serum cholesterol at the timepoints examined between MAP exposed sheep that were susceptible and those that were resistant to Johne's disease. There was a similar elevation in serum cholesterol at 9 wpi in cattle with histopathological gut lesions associated with disease or those with an early high IFN-γ response. Total serum cholesterol in exposed cattle was significantly lower when compared to controls at 13 wpi. Taken together, these results demonstrate changes in serum cholesterol following MAP exposure and disease progression which could reflect novel aspects of the pathogenesis and immune response associated with MAP infection in both sheep and cattle.
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Affiliation(s)
- M D Johansen
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Rd, Camden 2570, NSW, Australia
| | - K de Silva
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Rd, Camden 2570, NSW, Australia
| | - K M Plain
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Rd, Camden 2570, NSW, Australia
| | - D J Begg
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Rd, Camden 2570, NSW, Australia
| | - R J Whittington
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Rd, Camden 2570, NSW, Australia; School of Life & Environmental Sciences, The University of Sydney, Australia
| | - A C Purdie
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Rd, Camden 2570, NSW, Australia.
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Phythian CJ, Jackson B, Bell R, Citer L, Barwell R, Windsor PA. Abattoir surveillance of Sarcocystis spp., Cysticercosis ovis and Echinococcus granulosus in Tasmanian slaughter sheep, 2007-2013. Aust Vet J 2018; 96:62-68. [PMID: 29479682 DOI: 10.1111/avj.12670] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 06/12/2017] [Accepted: 07/31/2017] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To estimate the prevalence of macroscopic Sarcocystis spp., Cysticercus ovis and Echinococcus granulosus recorded at routine postmortem inspection of Tasmanian slaughter sheep during 2007 to 2013. METHODS A retrospective analysis of routine postmortem meat inspection data maintained on 352,325 Tasmanian adult slaughter sheep inspected across nine abattoirs in Tasmania, Victoria and South Australia as part of the National Sheep Health Monitoring Project (NSHMP). RESULTS During the period 1 September 2007 to 30 June 2013, the estimated prevalence of macroscopic Sarcocystis spp. was 14.3%, C. ovis was 3.2% and E. granulosus was 0.01%. Mean Sarcocystis spp. line prevalence ranged from 0% to 33.5%. Significant between-abattoir differences in the level of sarcosporidiosis (P < 0.001) and C. ovis were found (P < 0.001). Overall, very low levels of hydatidosis were recorded throughout the surveillance period. Predicted within-line prevalence of macroscopic sarcocysts in animals coming from a known/recorded local government area (LGA) (P < 0.001) was lower than that of lines where the LGA was unknown or not recorded. A higher prevalence of sarcocystosis was recorded in lines of sheep aged ≥ 2 years compared with those < 2 years (P < 0.001). CONCLUSION Reasons for the significant between-abattoir differences in recorded levels of ovine sarcosporidiosis and cysticercosis remain unknown, but may represent sampling bias, with subsets of slaughter sheep going to abattoirs with different tiers or access to markets. Further investigation into apparent differences, including epidemiological studies of properties with high lesion prevalence, comparing meat inspector diagnostic sensitivity, assessing the effect of line speed and tiers and market access in different abattoirs, may be useful.
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Affiliation(s)
- C J Phythian
- Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Institute for Production Animal Clinical Medicine, Section for Small Ruminants, 4325 Sandnes, Norway
| | - B Jackson
- Biosecurity Tasmania, Department for Primary Industries, Parks, Water and Environment, Tasmanian Government, Launceston, Tasmania
| | - R Bell
- Biosecurity Tasmania, Department for Primary Industries, Parks, Water and Environment, Tasmanian Government, Launceston, Tasmania
| | - L Citer
- Animal Health Australia, Braddon Australia Capital Territory, Australia
| | - R Barwell
- Animal Health Australia, Braddon Australia Capital Territory, Australia
| | - P A Windsor
- University of Sydney, Faculty of Veterinary Science, Camden, New South Wales, Australia
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Gautam M, Ridler A, Wilson PR, Heuer C. Control of clinical paratuberculosis in New Zealand pastoral livestock. N Z Vet J 2017; 66:1-8. [DOI: 10.1080/00480169.2017.1379914] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- M Gautam
- Institute of Veterinary, Animal and Biomedical Sciences (IVABS), EpiCentre, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand
| | - A Ridler
- International Sheep Research Centre, IVABS, Massey University, Private Bag 11 222, Palmerston North, New Zealand
| | - PR Wilson
- Institute of Veterinary, Animal and Biomedical Sciences (IVABS), EpiCentre, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand
| | - C Heuer
- Institute of Veterinary, Animal and Biomedical Sciences (IVABS), EpiCentre, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand
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Zhou Z, Mitchell RM, Gutman J, Wiegand RE, Mwandama DA, Mathanga DP, Skarbinski J, Shi YP. Pooled PCR testing strategy and prevalence estimation of submicroscopic infections using Bayesian latent class models in pregnant women receiving intermittent preventive treatment at Machinga District Hospital, Malawi, 2010. Malar J 2014; 13:509. [PMID: 25522751 PMCID: PMC4301903 DOI: 10.1186/1475-2875-13-509] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 12/14/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Low malaria parasite densities in pregnancy are a diagnostic challenge. PCR provides high sensitivity and specificity in detecting low density of parasites, but cost and technical requirements limit its application in resources-limited settings. Pooling samples for PCR detection was explored to estimate prevalence of submicroscopic malaria infection in pregnant women at delivery. Previous work uses gold-standard based methods to calculate sensitivity and specificity of tests, creating a challenge when newer methodologies are substantially more sensitive than the gold standard. Thus prevalence was estimated using Bayesian latent class models (LCMs) in this study. METHODS Nested PCR (nPCR) for the 18S rRNA gene subunit of Plasmodium falciparum was conducted to detect malaria infection in microscopy-negative Malawian women on IPTp. Two-step sample pooling used dried blood spot samples (DBSs) collected from placenta or periphery at delivery. Results from nPCR and histology as well as previously published data were used to construct LCMs to estimate assay sensitivity and specificity. Theoretical confidence intervals for prevalence of infection were calculated for two-step and one-step pooling strategies. RESULTS Of 617 microscopy-negative Malawian women, 39 (6.3%) were identified as actively infected by histology while 52 (8.4%) were positive by nPCR. One hundred forty (22.7%) individuals had past infection assessed by histology. With histology as a reference, 72% of women in the active infection group, 7.1% in the past infection group and 3.2% in histology-negative group were nPCR positive. Using latent class models without a gold standard, histology had a median sensitivity of 49.7% and specificity of 97.6% for active infection while PCR had a median sensitivity of 96.0% and specificity of 99.1%. The true prevalence of active infection was estimated at 8.0% (CI: 5.8-10.5%) from PCR. PCR also had similar sensitivity for detecting either peripheral or placental malaria for submicroscopic infections. One-step pooling would give similar confidence intervals for pool sizes less than 20 while reducing the number of tests performed. CONCLUSIONS Pooled nPCR testing was a sensitive and resource-efficient strategy and LCMs provided precise prevalence estimates of submicroscopic infections. Compared to two-step pooling, one-step pooling could provide similar prevalence estimates at population levels with many fewer tests required.
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Affiliation(s)
- Zhiyong Zhou
- Malaria Branch and Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
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Estimation of flock/herd-level true Mycobacterium avium subspecies paratuberculosis prevalence on sheep, beef cattle and deer farms in New Zealand using a novel Bayesian model. Prev Vet Med 2014; 117:447-55. [DOI: 10.1016/j.prevetmed.2014.10.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 10/03/2014] [Accepted: 10/04/2014] [Indexed: 11/20/2022]
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Biet F, Boschiroli ML. Non-tuberculous mycobacterial infections of veterinary relevance. Res Vet Sci 2014; 97 Suppl:S69-77. [PMID: 25256964 DOI: 10.1016/j.rvsc.2014.08.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 08/13/2014] [Accepted: 08/23/2014] [Indexed: 11/17/2022]
Abstract
Mycobacteria play an important role in human and animal health fields. We here examine the place of non tuberculous mycobacteria (NTM) infections in the veterinary context. Relevant aspects of a reference laboratory experience and a literature review are presented in this article. Importance is given both to productivity and to economic losses due to misdiagnosis with bovine tuberculosis and paratuberculosis. The impact NTM may have is relative to geographical location, ecology, husbandry, extent of surveillance programs and bovine tuberculosis and paratuberculosis prevalence. The role of the most relevant NTM in animal disease is summarized with a special focus on Mycobacterium avium subsp. paratuberculosis, given its role as causative agent of paratuberculosis, a disease with huge economic consequences for ruminant livestock.
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Affiliation(s)
- Franck Biet
- Institut National de la Recherche Agronomique, Infectiologie et Santé Publique, INRA Centre Val de Loire, Université de Tours, Unité Mixte de Recherches 1282, 37380 Nouzilly, France
| | - Maria Laura Boschiroli
- University Paris-Est, Anses, Laboratory for Animal Health, Bovine tuberculosis National Reference Laboratory, Bacterial Zoonoses Unit, 23, avenue du Général de Gaulle, 94706 Maisons-Alfort, France.
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Hunnam JC, Wilson PR, Heuer C, Stringer L, Clark RG, Mackintosh CG. Association betweenMycobacterium aviumsubspeciesparatuberculosisand lymph node size in New Zealand farmed deer (Cervus elaphus). N Z Vet J 2013; 61:133-40. [DOI: 10.1080/00480169.2012.755886] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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VinodhKumar OR, Gunaseelan L, Ronald BSM, Sakthivelan SM. Slaughterhouse prevalence of ovine paratuberculosis in Southern India. Trop Anim Health Prod 2012; 45:1063-9. [DOI: 10.1007/s11250-012-0321-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2012] [Indexed: 11/28/2022]
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15
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Anna Rita A, Victor NN, Silvia P, Luciana P, Anastasia D, Vincenzo C. Ovine paratuberculosis: a seroprevalence study in dairy flocks reared in the marche region, Italy. Vet Med Int 2011; 2011:782875. [PMID: 21876850 PMCID: PMC3163026 DOI: 10.4061/2011/782875] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Revised: 04/14/2011] [Accepted: 06/12/2011] [Indexed: 01/30/2023] Open
Abstract
In order to fulfil the seroprevalence gap on Mycobacterium avium subsp. paratuberculosis infection in ovine dairy farms of Marche region (central Italy), a stratified study was carried out on 2086 adult female sheep randomly chosen from 38 herds selected in Ancona and Macerata provinces. 73.7% flocks resulted infected by a commercial ELISA test (Pourquier, France), with a mean seroprevalence of 6.29% of sampled sheep in both provinces. A higher number of MAP seropositive ewes was recorded in the large herds' consistence than in the small and medium herds' consistence (P = 0.0269), and a greater percentage of infected sheep was obtained among female at early/late than in peak lactation stage (P = 0.0237). MAP infection was confirmed in 12.6% of infected farms by faecal culture. The true sheep-level seroprevalence was 15.1% ± 7.3%.
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Affiliation(s)
- Attili Anna Rita
- School of Veterinary Medical Sciences, University of Camerino, via Circonvallazione 93-95, 62024 Matelica, Italy
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Over K, Crandall PG, O'Bryan CA, Ricke SC. Current perspectives on Mycobacterium avium subsp. paratuberculosis, Johne's disease, and Crohn's disease: a review. Crit Rev Microbiol 2011; 37:141-56. [PMID: 21254832 DOI: 10.3109/1040841x.2010.532480] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Mycobacterium avium subsp. paratuberculosis (MAP) causes the disease of cattle, Johne's. The economic impact of this disease includes early culling of infected cattle, reduced milk yield, and weight loss of cattle sold for slaughter. There is a possible link between MAP and Crohn's disease, a human inflammatory bowel disease. MAP is also a potential human food borne pathogen because it survives current pasteurization treatments. We review the current knowledge of MAP, Johne's disease and Crohn's disease and note directions for future work with this organism including rapid and economical detection, effective management plans and preventative measures.
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Affiliation(s)
- Ken Over
- Center for Food Safety and Food Science Department, University of Arkansas, 2650 N. Young Ave., Fayetteville, AR 72704, USA
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Al-Majali AM, Jawasreh K, Nsour AA. Epidemiological studies on foot and mouth disease and paratuberculosis in small ruminants in Tafelah and Ma’an, Jordan. Small Rumin Res 2008. [DOI: 10.1016/j.smallrumres.2008.05.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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18
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Moloney BJ, Whittington RJ. Cross species transmission of ovine Johne's disease from sheep to cattle: an estimate of prevalence in exposed susceptible cattle. Aust Vet J 2008; 86:117-23. [DOI: 10.1111/j.1751-0813.2008.00272.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Toribio JALML, Sergeant ESG. A comparison of methods to estimate the prevalence of ovine Johne's infection from pooled faecal samples. Aust Vet J 2007; 85:317-24. [PMID: 17685977 DOI: 10.1111/j.1751-0813.2007.00188.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To compare estimates of ovine Johne's infection prevalence produced by several alternate methods based on pooled faecal culture (PFC) results with prevalence estimates based on individual faecal culture (IFC). PROCEDURE Seven methods for estimating prevalence of infection based on PFC results were incorporated in a computer program, including methods for imperfect test sensitivity and specificity, for variable pool size and a Bayesian method that incorporates prior knowledge about test performance and prevalence. These methods were then used to analyse PFC data at one observation 30 months post-vaccination in a field trial of a killed vaccine for the control of OJD, undertaken on three farms in New South Wales. RESULTS Prevalence estimates, for three methods that assume a perfect test, were close to the IFC estimate, whereas for three other methods that assume an imperfect test, the estimated prevalence was generally higher than the IFC estimate. In comparison, the Bayesian approach produced more variable estimates that were substantially higher than the IFC estimate when an inappropriately high prior estimate of prevalence was used. CONCLUSION Despite the limitations of each method, two methods provided accurate and reasonable estimates of the prevalence assessed by IFC in all instances, and are appropriate for the analysis of data from this vaccine trial. One of these methods also has the advantage of allowing for variable pool size. However, further research is needed to develop a method that will simultaneously account for variation in pool size and in test sensitivity and specificity.
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Affiliation(s)
- J-A L M L Toribio
- Faculty of Veterinary Science, The University of Sydney, Camden NSW 2570, Australia.
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Abstract
OBJECTIVE The objective of this study was to determine the sensitivity of abattoir surveillance of intestinal tract lesions for detecting ovine Johne's disease (OJD) under normal meatwork conditions. DESIGN The design of this study was a diagnostic test validation. The three OJD inspectors were the diagnostic test and follow-up histopathological examination was used for test validation. PROCEDURE Approximately 1200 sheep were procured from known high prevalence OJD infected farms. The sheep viscera were tagged (numbered) and then examined as they were processed on the abattoir line by three experienced meat inspectors. Their observations were independently recorded on a cassette tape. Specified sections of viscera were prepared and subjected to histopathological examination and these results were compared with the inspector diagnoses. RESULTS The sensitivity of abattoir inspection for OJD varied between inspectors from 53 percent to 87 percent. The specificity varied from 97 to 100 percent. It appeared that the level of sensitivity for detecting disease was higher in lines of sheep where the disease was more prevalent. It also appeared that formal training was an important aspect in ensuring a high level CONCLUSION Abattoir surveillance is a very economical and rapid method of assessing the OJD status of sheep. On the basis of these results it is reasonable to suggest that abattoir surveillance has a sensitivity of approximately 70 percent. This technique is useful as an ancillary to other testing regimes for negative assurance programs where a sheep identification system is used.
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Sergeant ESG, Marshall DJ, Eamens GJ, Kearns C, Whittington RJ. Evaluation of an absorbed ELISA and an agar-gel immuno-diffusion test for ovine paratuberculosis in sheep in Australia. Prev Vet Med 2003; 61:235-48. [PMID: 14623409 DOI: 10.1016/j.prevetmed.2003.08.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The sensitivities and specificities of an absorbed enzyme-linked immunosorbent assay (ELISA) and an agar-gel immuno-diffusion (AGID) test for the detection of Johne's disease in sheep were estimated using data from six known infected and 12 assumed uninfected sheep flocks. Sensitivities were estimated for all histologically positive sheep, as well as by histological lesion score, lesion type (paucibacillary or multibacillary) and sheep body-condition score, with ELISA sensitivities estimated at 95 and 99% specificity. Logistic-regression analysis was used to test for significant effects of lesion score and condition score, with flock included in the model as a random effect. Estimated specificities were 95% (95% CI: 93.4, 95.6%) and 99% (98.4, 99.4%) for ELISA cut-point ratios of 2.4 and 3.6, respectively, and 100% (99.7, 100.0%) for the AGID. Estimated sensitivities for all infected sheep were 41.5% (35.0, 48.3%), 21.9% (16.6, 27.9%) and 24.6% (19.1, 30.7%) for ELISA cut-point ratios of 2.4 and 3.6 and for AGID, respectively. Sensitivities of all tests and cut-points varied significantly between flocks and between categories of lesion score and condition score. Sensitivity ranged from 25 to 73, 10 to 47 and 9.2 to 63% between flocks, for the ELISA with cut-points of 2.4 and 3.6, and for the AGID, respectively. Sensitivity was highest in thin sheep and in sheep with multibacillary lesions. The effects of lesion type and condition score on test sensitivity were significant in the logistic regressions for the AGID and ELISA at both cut-points and the flock effect was significant for the AGID but not for the ELISA at either cut-point.
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Affiliation(s)
- E S G Sergeant
- AusVet Animal Health Services, 69 Turner Crescent, NSW 2800, Orange, Australia.
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Sergeant ESG. Estimated flock-prevalence and distribution of ovine Johne's disease in Australia at December 2001. Aust Vet J 2003; 81:768-9. [PMID: 15080491 DOI: 10.1111/j.1751-0813.2003.tb14612.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- E S G Sergeant
- AusVet Animal Health Services, 69 Turner Crescent, Orange New South Wales 2800
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