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Martí-García B, Priestnall SL, Suárez-Bonnet A. Pathology and causes of death in captive meerkats ( Suricata suricatta). Vet Q 2023; 43:1-9. [PMID: 37140628 DOI: 10.1080/01652176.2023.2211120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023] Open
Abstract
BACKGROUND Meerkats (Suricata suricatta) are endemic carnivores of southern Africa and, although currently listed as "least concern" by the International Union for Conservation of Nature (IUCN) red list, there is evidence of a significant decrease in wild populations mainly attributed to effects of climate change. Little is known about diseases associated with mortality in captive meerkats. AIM To characterise macroscopic and microscopic lesions that accounted for the death or euthanasia in a series of captive meerkats. MATERIAL AND METHODS Eight captive meerkats submitted for post-mortem examination between 2018 and 2022. RESULTS Three animals died unexpectedly without clinical signs, 2 exhibited neurological signs, 2 collapsed after con-specific fighting and 1 showed gastrointestinal signs. Common pathological findings of this study that may be related to the death of captive meerkats included foreign bodies (trichobezoars or plastic materials) within the alimentary tract, traumatic penetrating injuries or starvation associated with abnormal social behaviours (bullying and con-specific attacks), verminous pneumonia and systemic atherosclerosis. Common incidental findings included pulmonary edema and congestion, cholesterol granulomas, pulmonary adenomas and vertebral spondylosis. CONCLUSIONS Non-infectious diseases outreach infectious diseases as causes of mortality in captive meerkats including, foreign bodies within the alimentary tract, con-specific attacks and systemic atherosclerosis, which is described for the first time. These data should raise concern about appropriate husbandry (e.g. environmental enrichment, cleaning of facilities and diet formulation) by zookeepers and emphasise the need for further study of meerkat mortality in both captive and wild populations.
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Affiliation(s)
- Bernat Martí-García
- Pathobiology & Population Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, United Kingdom, AL9 7TA
| | - Simon L Priestnall
- Pathobiology & Population Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, United Kingdom, AL9 7TA
| | - Alejandro Suárez-Bonnet
- Pathobiology & Population Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, United Kingdom, AL9 7TA
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Müller-Klein N, Risely A, Schmid DW, Manser M, Clutton-Brock T, Sommer S. Two decades of tuberculosis surveillance reveal disease spread, high levels of exposure and mortality and marked variation in disease progression in wild meerkats. Transbound Emerg Dis 2022; 69:3274-3284. [PMID: 35947092 DOI: 10.1111/tbed.14679] [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: 05/03/2022] [Revised: 07/20/2022] [Accepted: 07/31/2022] [Indexed: 02/07/2023]
Abstract
Infections with tuberculosis (TB)-causing agents of the Mycobacterium tuberculosis complex threaten human, livestock and wildlife health globally due to the high capacity to cross trans-species boundaries. Tuberculosis is a cryptic disease characterized by prolonged, sometimes lifelong subclinical infections, complicating disease monitoring. Consequently, our understanding of infection risk, disease progression, and mortality across species affected by TB remains limited. The TB agent Mycobacterium suricattae was first recorded in the late 1990s in a wild population of meerkats inhabiting the Kalahari in South Africa and has since spread considerably, becoming a common cause of meerkat mortality. This offers an opportunity to document the epidemiology of naturally spreading TB in a wild population. Here, we synthesize more than 25 years' worth of TB reporting and social interaction data across 3420 individuals to track disease spread, and quantify rates of TB social exposure, progression, and mortality. We found that most meerkats had been exposed to the pathogen within eight years of first detection in the study area, with exposure reaching up to 95% of the population. Approximately one quarter of exposed individuals progressed to clinical TB stages, followed by physical deterioration and death within a few months. Since emergence, 11.6% of deaths were attributed to TB, although the true toll of TB-related mortality is likely higher. Lastly, we observed marked variation in disease progression among individuals, suggesting inter-individual differences in both TB susceptibility and resistance. Our results highlight that TB prevalence and mortality could be higher than previously reported, particularly in species or populations with complex social group dynamics. Long-term studies, such as the present one, allow us to assess temporal variation in disease prevalence and progression and quantify exposure, which is rarely measured in wildlife. Long-term studies are highly valuable tools to explore disease emergence and ecology and study host-pathogen co-evolutionary dynamics in general, and its impact on social mammals.
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Affiliation(s)
- Nadine Müller-Klein
- Conservation Genomics and EcoHealth, Institute for Evolutionary Ecology and Conservation Genomics, Ulm, Germany
| | - Alice Risely
- Conservation Genomics and EcoHealth, Institute for Evolutionary Ecology and Conservation Genomics, Ulm, Germany
| | - Dominik W Schmid
- Conservation Genomics and EcoHealth, Institute for Evolutionary Ecology and Conservation Genomics, Ulm, Germany
| | - Marta Manser
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.,Mammal Research Institute, University of Pretoria, Pretoria, South Africa.,Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa
| | - Tim Clutton-Brock
- Mammal Research Institute, University of Pretoria, Pretoria, South Africa.,Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa.,Large Animal Research Group, Department of Zoology, University of Cambridge, Cambridge, UK
| | - Simone Sommer
- Conservation Genomics and EcoHealth, Institute for Evolutionary Ecology and Conservation Genomics, Ulm, Germany
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CHARACTERIZING TUBERCULOSIS PROGRESSION IN WILD MEERKATS (SURICATA SURICATTA) FROM FECAL SAMPLES AND CLINICAL SIGNS. J Wildl Dis 2022; 58:309-321. [PMID: 35255146 DOI: 10.7589/jwd-d-21-00063] [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: 04/16/2021] [Accepted: 11/03/2021] [Indexed: 11/20/2022]
Abstract
Tuberculosis (TB) is an increasing threat to wildlife, yet tracking its spread is challenging because infections often appear to be asymptomatic, and diagnostic tools such as blood tests can be invasive and resource intensive. Our understanding of TB biology in wildlife is therefore limited to a small number of well-studied species. Testing of fecal samples using PCR is a noninvasive method that has been used to detect Mycobacterium bovis shedding amongst badgers, yet its utility more broadly for TB monitoring in wildlife is unclear. We combined observation data of clinical signs with PCR testing of 388 fecal samples to characterize longitudinal dynamics of TB progression in 66 wild meerkats (Suricata suricatta) socially exposed to Mycobacterium suricattae between 2000 and 2018. Our specific objectives were 1) to test whether meerkat fecal samples can be used to monitor TB; 2) to characterize TB progression between three infection states (PCR-negative exposed, PCR-positive asymptomatic, and PCR positive with clinical signs); and 3) estimate individual heterogeneity in TB susceptibility, defined here as the time between TB exposure and detection, and survival after TB detection. We found that the TB detection probability once meerkats developed clinical signs was 13% (95% confidence interval 3-46%). Nevertheless, with an adapted test protocol of 10 PCR replicates per sample we detected hidden TB infections in 59% of meerkats before the onset of clinical signs. Meerkats became PCR positive approximately 14 mo after initial exposure, developed clinical signs approximately 1 yr after becoming PCR positive, and died within 5 mo of developing clinical signs. Individual variation in disease progression was high, with meerkats developing clinical signs from immediately after exposure to 3.4 yr later. Overall, our study generates novel insights into wildlife TB progression, and may help guide adapted management strategies for TB-susceptible wildlife populations.
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Patterson SJ, Clutton-Brock TH, Pfeiffer DU, Drewe JA. Trait-Based Vaccination of Individual Meerkats (Suricata suricatta) against Tuberculosis Provides Evidence to Support Targeted Disease Control. Animals (Basel) 2022; 12:ani12020192. [PMID: 35049814 PMCID: PMC8772857 DOI: 10.3390/ani12020192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 12/14/2022] Open
Abstract
Simple Summary There is evidence to show that, within a population, some individuals are more likely to spread infections than others. When trying to protect a population against infection, most strategies aim to vaccinate as many individuals as possible. However, vaccinating wildlife is difficult because individuals are difficult to find and capture. For wildlife therefore, the ideal strategy would involve targeting vaccinations at those individuals most likely to transmit infection, thus gaining maximum benefit from capturing a small number of individuals. Whilst this seems a very attractive solution, very few studies have attempted to provide evidence to support this theory. This study focuses on a population of meerkats with a history of tuberculosis. Previous work has suggested that socially dominant individuals are most likely to transmit infection, with subordinates most likely to become infected. Therefore, whilst some social groups were left untreated as a baseline, in others, either dominants or subordinates were vaccinated. All groups were monitored for two years, after which time the infection data was analysed. Groups in which vaccinations had been used showed reduced infection rates suggesting that the targeted approach had reduced transmission. A targeted approach may therefore offer an efficient option for vaccinating wildlife in the future. Abstract Individuals vary in their potential to acquire and transmit infections, but this fact is currently underexploited in disease control strategies. We trialled a trait-based vaccination strategy to reduce tuberculosis in free-living meerkats by targeting high-contact meerkats (socially dominant individuals) in one study arm, and high-susceptibility individuals (young subordinates) in a second arm. We monitored infection within vaccinated groups over two years comparing the results with untreated control groups. Being a member of a high-contact group had a protective effect on individuals’ survival times (Hazard Ratio = 0.5, 95% Confidence Interval, CI: 0.29–0.88, p = 0.02) compared to control groups. Over the study, odds of testing positive for tuberculosis increased more than five-fold in control groups (Odds Ratio = 5.40, 95% CI = 0.94–30.98, p = 0.058); however, no increases were observed in either of the treatment arms. Targeted disease control approaches, such as the one described in this study, allow for reduced numbers of interventions. Here, trait-based vaccination was associated with reduced infection rates and thus has the potential to offer more efficient alternatives to traditional mass-vaccination policies. Such improvements in efficiency warrant further study and could make infectious disease control more practically achievable in both animal (particularly wildlife) and human populations.
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Affiliation(s)
- Stuart J. Patterson
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, UK; (D.U.P.); (J.A.D.)
- Correspondence:
| | - Tim H. Clutton-Brock
- Large Animal Research Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK;
- Mammal Research Institute, University of Pretoria, Hatfield, Pretoria 0028, South Africa
| | - Dirk U. Pfeiffer
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, UK; (D.U.P.); (J.A.D.)
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China
| | - Julian A. Drewe
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, UK; (D.U.P.); (J.A.D.)
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Patterson SJ, Clarke C, Clutton-Brock TH, Miller MA, Parsons SDC, Pfeiffer DU, Vergne T, Drewe JA. Combining Analytical Approaches and Multiple Sources of Information to Improve Interpretation of Diagnostic Test Results for Tuberculosis in Wild Meerkats. Animals (Basel) 2021; 11:3453. [PMID: 34944230 PMCID: PMC8698085 DOI: 10.3390/ani11123453] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/25/2021] [Accepted: 11/29/2021] [Indexed: 11/17/2022] Open
Abstract
Diagnostic tests are used to classify individual animals' infection statuses. However, validating test performance in wild animals without gold standard tests is extremely challenging, and the issue is further complicated in chronic conditions where measured immune parameters vary over time. Here, we demonstrate the value of combining evidence from different diagnostic approaches to aid interpretation in the absence of gold standards, large sample sizes, and controlled environments. Over a two-year period, we sampled 268 free-living meerkats (Suricata suricatta) longitudinally for Mycobacterium suricattae (a causative agent of tuberculosis), using three ante-mortem diagnostic tests based on mycobacterial culture, and antigen-specific humoral and cell-mediated immune responses, interpreting results both independently and in combination. Post-mortem cultures confirmed M. suricattae infection in 22 animals, which had prior ante-mortem information, 59% (13/22) of which were test-positive on a parallel test interpretation (PTI) of the three ante-mortem diagnostic assays (95% confidence interval: 37-79%). A similar ability to detect infection, 65.7% (95% credible interval: 42.7-84.7%), was estimated using a Bayesian approach to examine PTI. Strong evidence was found for a near doubling of the hazard of death (Hazard Ratio 1.75, CI: 1.14-2.67, p = 0.01), associated with a positive PTI result, thus demonstrating that these test results are related to disease outcomes. For individual tests, small sample sizes led to wide confidence intervals, but replication of conclusions, using different methods, increased our confidence in these results. This study demonstrates that combining multiple methodologies to evaluate diagnostic tests in free-ranging wildlife populations can be a useful approach for exploiting such valuable datasets.
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Affiliation(s)
- Stuart J. Patterson
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield AL9 7TA, UK; (D.U.P.); (J.A.D.)
| | - Charlene Clarke
- SAMRC Centre for TB Research, DSI/NRF Centre of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 8000, South Africa; (C.C.); (M.A.M.); (S.D.C.P.)
| | - Tim H. Clutton-Brock
- Large Animal Research Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK;
- Mammal Research Institute, University of Pretoria, Hatfield, Pretoria 0028, South Africa
| | - Michele A. Miller
- SAMRC Centre for TB Research, DSI/NRF Centre of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 8000, South Africa; (C.C.); (M.A.M.); (S.D.C.P.)
| | - Sven D. C. Parsons
- SAMRC Centre for TB Research, DSI/NRF Centre of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 8000, South Africa; (C.C.); (M.A.M.); (S.D.C.P.)
| | - Dirk U. Pfeiffer
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield AL9 7TA, UK; (D.U.P.); (J.A.D.)
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China
| | - Timothée Vergne
- UMR ENVT-INRAE IHAP, National Veterinary School of Toulouse, 31300 Toulous, France;
| | - Julian A. Drewe
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield AL9 7TA, UK; (D.U.P.); (J.A.D.)
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Duncan C, Manser MB, Clutton‐Brock T. Decline and fall: The causes of group failure in cooperatively breeding meerkats. Ecol Evol 2021; 11:14459-14474. [PMID: 34765119 PMCID: PMC8571573 DOI: 10.1002/ece3.7655] [Citation(s) in RCA: 3] [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: 12/02/2020] [Revised: 02/15/2021] [Accepted: 02/28/2021] [Indexed: 12/30/2022] Open
Abstract
In many social vertebrates, variation in group persistence exerts an important effect on individual fitness and population demography. However, few studies have been able to investigate the failure of groups or the causes of the variation in their longevity. We use data from a long-term study of cooperatively breeding meerkats, Suricata suricatta, to investigate the different causes of group failure and the factors that drive these processes. Many newly formed groups failed within a year of formation, and smaller groups were more likely to fail. Groups that bred successfully and increased their size could persist for several years, even decades. Long-lived groups principally failed in association with the development of clinical tuberculosis, Mycobacterium suricattae, a disease that can spread throughout the group and be fatal for group members. Clinical tuberculosis was more likely to occur in groups that had smaller group sizes and that had experienced immigration.
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Affiliation(s)
- Chris Duncan
- Department of ZoologyUniversity of CambridgeCambridgeUK
- Kalahari Research Centre, Kuruman River ReserveVan ZylsrusSouth Africa
| | - Marta B. Manser
- Kalahari Research Centre, Kuruman River ReserveVan ZylsrusSouth Africa
- Animal BehaviourDepartment of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
| | - Tim Clutton‐Brock
- Department of ZoologyUniversity of CambridgeCambridgeUK
- Kalahari Research Centre, Kuruman River ReserveVan ZylsrusSouth Africa
- Mammal Research InstituteUniversity of PretoriaPretoriaSouth Africa
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Review of Methods Used for Diagnosing Tuberculosis in Captive and Free-Ranging Non-Bovid Species (2012-2020). Pathogens 2021; 10:pathogens10050584. [PMID: 34064571 PMCID: PMC8151627 DOI: 10.3390/pathogens10050584] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/06/2021] [Accepted: 05/07/2021] [Indexed: 11/16/2022] Open
Abstract
The Mycobacterium tuberculosis complex (MTBC) is a group of bacteria that cause tuberculosis (TB) in diverse hosts, including captive and free-ranging wildlife species. There is significant research interest in developing immunodiagnostic tests for TB that are both rapid and reliable, to underpin disease surveillance and control. The aim of this study was to carry out an updated review of diagnostics for TB in non-bovid species with a focus predominantly on those based on measurement of immunity. A search was carried out to identify relevant papers meeting a pre-defined set of inclusion criteria. Forty-one papers were identified from this search, from which only twenty papers contained data to measure and compare diagnostic performance using diagnostic odds ratio. The diagnostic tests from each study were ranked based on sensitivity, specificity, and diagnostic odds ratio to define high performing tests. High sensitivity and specificity values across a range of species were reported for a new antigenic target, P22 complex, demonstrating it to be a reliable and accurate antigenic target. Since the last review of this kind was undertaken, the immunodiagnosis of TB in meerkats and African wild dogs was reported for the first time. Suid species showed the most consistent immunological responses and highlight a potential dichotomy between humoral and cellular immune responses.
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Mongoose ( Herpestes auropunctatus) May Not Be Reservoir Hosts for Mycobacterium bovis in Fiji Despite High Population Density and Direct Contact with Cattle. Vet Sci 2019; 6:vetsci6040085. [PMID: 31652969 PMCID: PMC6958361 DOI: 10.3390/vetsci6040085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 10/20/2019] [Accepted: 10/22/2019] [Indexed: 11/29/2022] Open
Abstract
The presence of a wildlife reservoir for Mycobacterium bovis complicates the eradication of bovine tuberculosis (BTB) from domestic cattle populations. For the BTB eradication program in Fiji, there is concern about the small Indian mongoose (Herpestes auropunctatus), which is overabundant and in direct contact with cattle. Consequently, a survey of mongooses trapped on three BTB affected dairy farms led to necropsy of 85 mongooses during January–February 2017. Thirty (35%) mongooses had gross pathological changes including possible granulomas detected at necropsy, and tissues from these animals were taken for histopathological examination. Granulomatous lesions were present in 53% of animals examined histopathologically but acid-fast bacilli were not observed and the majority of lesions in lung and kidney were associated with the nematodes Pulmostrongylus herpestis and Capillaria sp., respectively. Nevertheless, assuming test sensitivity of 35% for the current study, from this sample of 85 mongooses it can be concluded with 95% confidence that if present in the mongoose population susceptible to trapping, M. bovis prevalence was ≤10%. The prevalence of intercurrent lesions raised concerns about gross pathology as a screening test for M. bovis infection in mongooses in Fiji, and therefore pathogen detection methods such as bacterial culture and direct tissue PCR are recommended for future surveys. These are needed to completely rule out the mongoose as a reservoir host for M. bovis in Fiji.
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Fieweger RA, Wilburn KM, VanderVen BC. Comparing the Metabolic Capabilities of Bacteria in the Mycobacterium tuberculosis Complex. Microorganisms 2019; 7:E177. [PMID: 31216777 PMCID: PMC6617402 DOI: 10.3390/microorganisms7060177] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 06/10/2019] [Accepted: 06/15/2019] [Indexed: 02/06/2023] Open
Abstract
Pathogenic mycobacteria are known for their ability to maintain persistent infections in various mammals. The canonical pathogen in this genus is Mycobacterium tuberculosis and this bacterium is particularly successful at surviving and replicating within macrophages. Here, we will highlight the metabolic processes that M. tuberculosis employs during infection in macrophages and compare these findings with what is understood for other pathogens in the M. tuberculosis complex.
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Affiliation(s)
- Rachael A Fieweger
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850, USA.
| | - Kaley M Wilburn
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850, USA.
| | - Brian C VanderVen
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850, USA.
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Fico R, Mariacher A, Franco A, Eleni C, Ciarrocca E, Pacciarini ML, Battisti A. Systemic tuberculosis by MYCOBACTERIUM BOVIS in a free-ranging MARSICAN brown bear (URSUS ARCTOS MARSICANUS): a Case report. BMC Vet Res 2019; 15:152. [PMID: 31101105 PMCID: PMC6525449 DOI: 10.1186/s12917-019-1910-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 05/13/2019] [Indexed: 12/05/2022] Open
Abstract
Background Mycobacterium bovis is known to have a wide host range and has been isolated from numerous free-ranging wildlife species, carnivores included. In bears, M. bovis has been previously reported only from a culture of pooled lymph nodes of a black bear (Ursus americanus) in the absence of lesions. The aims of this study were to describe gross and microscopic pathological findings of M. bovis tuberculosis in a deceased Marsican brown bear (Ursus arctos marsicanus). Case presentation In March 2014, an adult female Marsican brown bear was found in the Abruzzo, Lazio and Molise National Park (Italy) showing severe non-specific clinical signs. The animal died soon after its discovery and the carcass was submitted to post-mortem examination to identify the cause of death. The bear was diagnosed with a severe Mycobacterium bovis infection, with both pathological and microbiological aspects suggesting ongoing generalization. A presumptive diagnosis of mycobacterial infection was initially made based on gross findings. Histopathology showed the presence of acid-fast bacilli in all sampled tissues along with poorly organized granulomatous lesions. Slow-growing Mycobacterium sp. was isolated from multiple organs (intestine, mesenteric lymph nodes, liver, spleen, lung and kidneys). The PCR and sequencing algorithm identified the Mycobacterium sp. isolate as M. bovis. Spoligotyping demonstrated that the M. bovis isolate belonged to spoligotype SB0120. Conclusions This is the first report of lethal M. bovis tuberculosis infection in a free-ranging brown bear. This pathogen could have serious adverse effects in an endangered relic population such as the Marsican brown bear. Stricter application of health regulations in force, surveillance of M. bovis infections in wild ungulates and carnivore scavengers, along with dismissal of supplementary feeding points intended for cattle or wildlife, are warranted to control the presence of bovine tuberculosis in wild and domestic animals in protected areas.
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Affiliation(s)
- Rosario Fico
- Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana, Viale Europa 30, 58100, Grosseto, Italy
| | - Alessia Mariacher
- Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana, Viale Europa 30, 58100, Grosseto, Italy.
| | - Alessia Franco
- Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana, Via Appia Nuova 1411, 00178, Rome, Italy
| | - Claudia Eleni
- Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana, Via Appia Nuova 1411, 00178, Rome, Italy
| | - Erika Ciarrocca
- Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana, Viale Europa 30, 58100, Grosseto, Italy
| | - Maria Lodovica Pacciarini
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia-Romagna, National Reference Laboratory for Bovine Tuberculosis, Via A. Bianchi 9, 25124, Brescia, Italy
| | - Antonio Battisti
- Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana, Via Appia Nuova 1411, 00178, Rome, Italy
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Lesellier S. Immunological responses of European badgers (Meles Meles) to infection with Mycobacterium bovis. Comp Immunol Microbiol Infect Dis 2018; 61:9-15. [PMID: 30502833 DOI: 10.1016/j.cimid.2018.09.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 09/11/2018] [Accepted: 09/13/2018] [Indexed: 12/17/2022]
Abstract
Mycobacterium bovis is the main cause of bovine tuberculosis and its eradication is proving difficult in many countries because of wildlife reservoirs, including European badgers (Meles meles) in the UK Ireland. Following the development of badger specific immunological reagents, many studies have shown that some aspects of the cellular and serological immune responses of badgers to virulent M. bovis and the attenuated M. bovis BCG (Bacille of Calmette and Guérin) strain are similar to those seen in other animal hosts infected with M. bovis. However, badgers also appear to have developed specific immunological responses to M. bovis infection which may be associated with mild inflammatory responses. Badgers may therefore represent an interesting natural host for M. bovis that can provide a more thorough understanding of efficient immunological responses to tuberculosis.
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Affiliation(s)
- Sandrine Lesellier
- Animal and Plant Health Agency, Woodham Lane, New Haw, KT15 3NB, United Kingdom.
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Church ME, Terio KA, Keel MK. Procyonidae, Viverridae, Hyenidae, Herpestidae, Eupleridae, and Prionodontidae. PATHOLOGY OF WILDLIFE AND ZOO ANIMALS 2018. [PMCID: PMC7148636 DOI: 10.1016/b978-0-12-805306-5.00012-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
This chapter covers the diseases and pathology of multiple taxonomic groups within the order Carnivora including Procyonidae several of the Feliformia carnivores. The overwhelming majority of knowledge about disease pathogenesis for these species is biased toward raccoons and concern for disease spread to humans and companion animals. Procyonids and feliform carnivores are ubiquitous in their environments and share habitat and environmental resources with other nondomestic and domestic carnivores and humans. As reservoirs for a number of important multispecies or zoonotic pathogens, surveys for pathogens that may be harbored or vectored by several of the species in this chapter, for example, raccoons (e.g., canine distemper virus, rabies, and leptospirosis) and civets (e.g., SARS coronavirus), have been active areas of investigation. Unfortunately, less research has focused on the potential effects of these pathogens on their hosts.
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Alexander KA, Laver PN, Williams MC, Sanderson CE, Kanipe C, Palmer MV. Pathology of the Emerging Mycobacterium tuberculosis Complex Pathogen, Mycobacterium mungi, in the Banded Mongoose ( Mungos mungo). Vet Pathol 2017; 55:303-309. [PMID: 29258402 DOI: 10.1177/0300985817741730] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Wild banded mongooses ( Mungos mungo) in northeastern Botswana and northwest Zimbabwe are infected with a novel Mycobacterium tuberculosis complex (MTC) pathogen, Mycobacterium mungi. We evaluated gross and histologic lesions in 62 infected mongooses (1999-2017). Many tissues contained multifocal irregular, lymphohistiocytic to granulomatous infiltrates and/or multifocal or coalescing noncaseating to caseating granulomas with variable numbers of intralesional acid-fast bacilli. Over one-third of nasal turbinates examined had submucosal lymphohistiocytic to granulomatous infiltrates, erosion and ulceration of the nasal mucosa, bony remodeling, and nasal distortion. Similar inflammatory cell infiltrates expanded the dermis of the nasal planum with frequent ulceration. However, even in cases with intact epidermis, acid-fast bacilli were present in variable numbers among dermal infiltrates and on the epidermal surface among desquamated cells and debris, most commonly in small crevices or folds. In general, tissue involvement varied among cases but was highest in lymph nodes (50/54, 93%), liver (39/53, 74%), spleen (37/51, 73%), and anal glands/sacs (6/8, 75%). Pulmonary lesions were present in 67% of sampled mongooses (35/52) but only in advanced disseminated disease. The pathological presentation of M. mungi in the banded mongoose is consistent with pathogen shedding occurring through scent-marking behaviors (urine and anal gland secretions) with new infections arising from contact with these contaminated olfactory secretions and percutaneous movement of the pathogen through breaks in the skin, nasal planum, and/or skin of the snout. Given the character and distribution of lesions and the presence of intracellular acid-fast bacilli, we hypothesize that pathogen spread occurs within the body through a hematogenous and/or lymphatic route. Features of prototypical granulomas such as multinucleated giant cells and peripheral fibrosis were rarely present in affected mongooses. Acid-fast bacilli were consistently found intracellularly, even in regions of necrosis. The mongoose genome has a unique deletion (RD1mon) that includes part of the encoding region for PPE68 (Rv3873), a gene co-operonic with PE35. These proteins can influence the host's cellular immune response to mycobacterial infections, and it remains uncertain how this deletion might contribute to observed patterns of pathology. M. mungi infection in banded mongooses is characterized by both a unique transmission and exposure route, as well as accompanying pathological features, providing an opportunity to increase our understanding of MTC pathogenesis across host-pathogen systems.
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Affiliation(s)
- Kathleen A Alexander
- 1 Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA, USA
- 2 CARACAL, Centre for Conservation of African Resources, Animals, Communities, and Land Use, Kasane, Botswana
| | - Peter N Laver
- 1 Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA, USA
| | - Mark C Williams
- 3 Section of Pathology, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Claire E Sanderson
- 1 Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA, USA
- 2 CARACAL, Centre for Conservation of African Resources, Animals, Communities, and Land Use, Kasane, Botswana
| | - Carly Kanipe
- 4 Department of Veterinary Pathology, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
- 5 Bacterial Diseases of Livestock Research Unit, National Animal Disease Center, Ames, IA, USA
| | - Mitchell V Palmer
- 5 Bacterial Diseases of Livestock Research Unit, National Animal Disease Center, Ames, IA, USA
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14
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Patterson S, Drewe JA, Pfeiffer DU, Clutton-Brock TH. Social and environmental factors affect tuberculosis related mortality in wild meerkats. J Anim Ecol 2017; 86:442-450. [PMID: 28186336 PMCID: PMC5413830 DOI: 10.1111/1365-2656.12649] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 01/31/2017] [Indexed: 11/27/2022]
Abstract
Tuberculosis (TB) is an important and widespread disease of wildlife, livestock and humans world‐wide, but long‐term empirical datasets describing this condition are rare. A population of meerkats (Suricata suricatta) in South Africa's Kalahari Desert have been diagnosed with Mycobacterium suricattae, a novel strain of TB, causing fatal disease in this group‐living species. This study aimed to find characteristics associated with clinical TB in meerkats. These characteristics could subsequently be used to identify ‘at‐risk’ animals within a population, and target these individuals for control measures. We conducted a retrospective study based on a unique, long‐term life‐history dataset of over 2000 individually identified animals covering a 14‐year period after the first confirmatory diagnosis of TB in this population in 2001. Individual‐ and group‐level risk factors were analysed using time‐dependent Cox regression to examine their potential influence on the time to development of end‐stage TB. Cases of disease involved 144 individuals in 27 of 73 social groups, across 12 of 14 years (an incidence rate of 3·78 cases/100 study years). At the individual level, increasing age had the greatest effect on risk of disease with a hazard ratio of 4·70 (95% CI: 1·92–11·53, P < 0·01) for meerkats aged 24–48 months, and a hazard ratio of 9·36 (3·34–26·25, P < 0·001) for animals aged over 48 months (both age categories compared with animals aged below 24 months). Previous group history of TB increased the hazard by a factor of 4·29 (2·00–9·17, P < 0·01), and an interaction was found between this variable and age. At a group level, immigrations of new group members in the previous year increased hazard by a factor of 3·00 (1·23–7·34, P = 0·016). There was weaker evidence of an environmental effect with a hazard ratio for a low rainfall (<200 mm) year of 2·28 (0·91–5·72, P = 0·079). Our findings identify potential individual characteristics on which to base targeted control measures such as vaccination. Additional data on the dynamics of the infection status of individuals and how this changes over time would complement these findings by enhancing understanding of disease progression and transmission, and thus the implications of potential management measures.
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Affiliation(s)
- Stuart Patterson
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield AL9 7TA, UK
| | - Julian A Drewe
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield AL9 7TA, UK
| | - Dirk U Pfeiffer
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield AL9 7TA, UK.,School of Veterinary Medicine, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR
| | - Tim H Clutton-Brock
- Large Animal Research Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.,Mammal Research Institute, University of Pretoria, Hatfield, Pretoria, South Africa
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15
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Thirunavukkarasu S, Plain KM, de Silva K, Marais BJ, Whittington RJ. Applying the One Health Concept to Mycobacterial Research - Overcoming Parochialism. Zoonoses Public Health 2017; 64:401-422. [PMID: 28084673 DOI: 10.1111/zph.12334] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Indexed: 12/27/2022]
Abstract
Mycobacterial infections remain a public health problem. Historically important, globally ubiquitous and with a wide host range, we are still struggling to control mycobacterial infections in humans and animals. While previous reviews have focused on individual mycobacterial infections in either humans or animals, a comprehensive review of the zoonotic aspect of mycobacteria in the context of the One Health initiative is lacking. With the purpose of providing a concise and comprehensive resource, we have collated literature to address the zoonotic potential of different mycobacterial species and elaborate on the necessity for an inter-sectorial approach to attain a new vision to combat mycobacterial infections.
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Affiliation(s)
- S Thirunavukkarasu
- Faculty of Veterinary Science, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia.,Boise Veterans Affairs Medical Center, Boise, ID, USA
| | - K M Plain
- Faculty of Veterinary Science, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - K de Silva
- Faculty of Veterinary Science, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - B J Marais
- Marie Bashir Institute for Infectious Diseases and Biosecurity and the Centre for Research Excellence in Emerging Infections, University of Sydney, Sydney, NSW, Australia
| | - R J Whittington
- Faculty of Veterinary Science, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
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16
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Clarke C, Patterson SJ, Drewe JA, van Helden PD, Miller MA, Parsons SDC. Development and evaluation of a diagnostic cytokine-release assay for Mycobacterium suricattae infection in meerkats (Suricata suricatta). BMC Vet Res 2017; 13:2. [PMID: 28052763 PMCID: PMC5209895 DOI: 10.1186/s12917-016-0927-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 12/15/2016] [Indexed: 01/24/2023] Open
Abstract
Background Sensitive diagnostic tools are necessary for the detection of Mycobacterium suricattae infection in meerkats (Suricata suricatta) in order to more clearly understand the epidemiology of tuberculosis and the ecological consequences of the disease in this species. We therefore aimed to develop a cytokine release assay to measure antigen-specific cell-mediated immune responses of meerkats. Results Enzyme-linked immunosorbent assays (ELISAs) were evaluated for the detection of interferon-gamma (IFN-γ) and IFN-γ inducible protein 10 (IP-10) in meerkat plasma. An IP-10 ELISA was selected to measure the release of this cytokine in whole blood in response to Bovigam® PC-HP Stimulating Antigen, a commercial peptide pool of M. bovis antigens. Using this protocol, captive meerkats with no known M. suricattae exposure (n = 10) were tested and results were used to define a diagnostic cut off value (mean plus 2 standard deviations). This IP-10 release assay (IPRA) was then evaluated in free-living meerkats with known M. suricattae exposure, categorized as having either a low, moderate or high risk of infection with this pathogen. In each category, respectively, 24.7%, 27.3% and 82.4% of animals tested IPRA-positive. The odds of an animal testing positive was 14.0 times greater for animals with a high risk of M. suricattae infection compared to animals with a low risk. Conclusion These results support the use of this assay as a measure of M. suricattae exposure in meerkat populations. Ongoing longitudinal studies aim to evaluate the value of the IPRA as a diagnostic test of M. suricattae infection in individual animals. Electronic supplementary material The online version of this article (doi:10.1186/s12917-016-0927-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Charlene Clarke
- SAMRC Centre for TB Research; DST/NRF Centre of Excellence for Biomedical Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Stuart James Patterson
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TA, UK
| | - Julian Ashley Drewe
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TA, UK
| | - Paul David van Helden
- SAMRC Centre for TB Research; DST/NRF Centre of Excellence for Biomedical Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Michele Ann Miller
- SAMRC Centre for TB Research; DST/NRF Centre of Excellence for Biomedical Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Sven David Charles Parsons
- SAMRC Centre for TB Research; DST/NRF Centre of Excellence for Biomedical Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.
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DIAGNOSIS AND IMPLICATIONS OF MYCOBACTERIUM BOVIS INFECTION IN BANDED MONGOOSES (MUNGOS MUNGO) IN THE KRUGER NATIONAL PARK, SOUTH AFRICA. J Wildl Dis 2016; 53:19-29. [PMID: 27788055 DOI: 10.7589/2015-11-318] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bovine tuberculosis (bTB) was first diagnosed in the Kruger National Park (KNP) in 1990. Research has since focused on the maintenance host, the African buffalo ( Syncerus caffer ) and clinically affected lion ( Panthera leo ). However, little is known about the role of small predators in tuberculosis epidemiology. During 2011-12, we screened banded mongooses ( Mungos mungo ) in the bTB high-prevalence zone of the KNP for Mycobacterium tuberculosis complex members. Fecal swabs, tracheal swabs, and tracheal lavages of 76 banded mongooses caught in cage traps within a 2-km radius of Skukuza Rest Camp were submitted for Mycobacterium culture, isolation, and species identification. Lesions and lymph node samples collected from 12 animals at postmortem examination were submitted for culture and histopathology. In lung and lymph nodes of two banded mongooses, well demarcated, irregularly margined, gray-yellow nodules of up to 5 mm diameter were identified with either central necrosis or calcification, characterized on histopathology as caseating necrosis with epithelioid macrophages or necrogranuloma with calcified centre. No acid fast bacteria were identified with Ziehl-Neelsen stain. We isolated Mycobacterium bovis from lung, lymph node, and liver samples, as well as from tracheal lavages and tracheal swab from the same two banded mongooses. Blood samples were positive by ElephantTB STAT-PAK® Assay for 12 and Enferplex™ TB Assay for five animals. Only the two banded mongooses positive on pathology and M. bovis culture were positive on both serologic assays. We provide evidence of bTB infection in banded mongooses in the KNP, demonstrate their ability to shed M. bovis , and propose a possible antemortem diagnostic algorithm. Our findings open the discussion around possible sources of infection and their significance at the human/wildlife interface in and around Skukuza.
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18
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Emerging Tuberculosis Pathogen Hijacks Social Communication Behavior in the Group-Living Banded Mongoose (Mungos mungo). mBio 2016; 7:mBio.00281-16. [PMID: 27165798 PMCID: PMC4895101 DOI: 10.1128/mbio.00281-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
An emerging Mycobacterium tuberculosis complex (MTC) pathogen, M. mungi, infects wild banded mongooses (Mungos mungo) in Northern Botswana, causing significant mortality. This MTC pathogen did not appear to be transmitted through a primary aerosol or oral route. We utilized histopathology, spoligotyping, mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR), quantitative PCR (qPCR), and molecular markers (regions of difference [RDs] from various MTC members, including region of difference 1 [RD1] from M. bovis BCG [RD1BCG], M. microti [RD1mic], and M. pinnipedii [RD1seal], genes Rv1510 [RD4], Rv1970 [RD7], Rv3877/8 [RD1], and Rv3120 [RD12], insertion element IS1561, the 16S RNA gene, and gene Rv0577 [cfp32]), including the newly characterized mongoose-specific deletion in RD1 (RD1mon), in order to demonstrate the presence of M. mungi DNA in infected mongooses and investigate pathogen invasion and exposure mechanisms. M. mungi DNA was identified in 29% of nasal planum samples (n = 52), 56% of nasal rinses and swabs (n = 9), 53% of oral swabs (n = 19), 22% of urine samples (n = 23), 33% of anal gland tissue (n = 18), and 39% of anal gland secretions (n = 44). The occurrence of extremely low cycle threshold values obtained with qPCR in anal gland and nasal planum samples indicates that high levels of M. mungi can be found in these tissue types. Histological data were consistent with these results, suggesting that pathogen invasion occurs through breaks in the nasal planum and/or skin of the mongoose host, which are in frequent contact with anal gland secretions and urine during olfactory communication behavior. Lesions in the lung, when present, occurred only with disseminated disease. No environmental sources of M. mungi DNA could be found. We report primary environmental transmission of an MTC pathogen that occurs in association with social communication behavior. Organisms causing infectious disease evolve modes of transmission that exploit environmental and host conditions favoring pathogen spread and persistence. We report a novel mode of environmental infectious disease transmission that occurs in association with olfactory secretions (e.g., urine and anal gland secretions), allowing pathogen exposure to occur within and between social groups through intricate social communication behaviors of the banded mongoose host. The presence of M. mungi in these environmentally deposited secretions would effectively circumvent natural social barriers (e.g., territoriality), facilitating between-group pathogen transmission in the absence of direct physical contact, a rare occurrence in this highly territorial species. This work identifies an important potential mechanism of pathogen transmission of epidemiological significance in social species. We also provide evidence of a novel mechanism of pathogen transmission for the MTC complex, where pathogen movement in the environment and host exposure dynamics are driven by social behavior.
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19
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Clarke C, Van Helden P, Miller M, Parsons S. Animal-adapted members of the Mycobacterium tuberculosis complex endemic to the southern African subregion. J S Afr Vet Assoc 2016; 87:1322. [PMID: 27246904 PMCID: PMC6138107 DOI: 10.4102/jsava.v87i1.1322] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Revised: 10/30/2015] [Accepted: 12/02/2015] [Indexed: 11/15/2022] Open
Abstract
Members of the Mycobacterium tuberculosis complex (MTC) cause tuberculosis (TB) in both animals and humans. In this article, three animal-adapted MTC strains that are endemic to the southern African subregion – that is, Mycobacterium suricattae, Mycobacterium mungi, and the dassie bacillus – are reviewed with a focus on clinical and pathological presentations, geographic distribution, genotyping methods, diagnostic tools and evolution. Moreover, factors influencing the transmission and establishment of TB pathogens in novel host populations, including ecological, immunological and genetic factors of both the host and pathogen, are discussed. The risks associated with these infections are currently unknown and further studies will be required for greater understanding of this disease in the context of the southern African ecosystem.
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Affiliation(s)
| | | | | | - Sven Parsons
- SAMRC Centre for TB Research, DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University.
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20
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Bongiovann L, Di Girolamo N, Della Salda L, Massimi M, Romanucci M, Selleri P. Sudden death in a captive meerkat (Suricata suricatta) with arterial medial and myocardial calcification. Asian Pac J Trop Biomed 2016. [DOI: 10.1016/j.apjtb.2016.01.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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21
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El-Sayed A, El-Shannat S, Kamel M, Castañeda-Vazquez MA, Castañeda-Vazquez H. Molecular Epidemiology of Mycobacterium bovis in Humans and Cattle. Zoonoses Public Health 2015; 63:251-64. [PMID: 26684712 DOI: 10.1111/zph.12242] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Indexed: 11/29/2022]
Abstract
Bovine tuberculosis (bTB), caused by Mycobacterium bovis (M. bovis), is a serious re-emerging disease in both animals and humans. The evolution of the Multi- and Extensively drug-resistant M. bovis strains (MDR-TB and XDR-TB) represents a global threat to public health. Worldwide, the disease is responsible for great economic losses in the veterinary field, serious threat to the ecosystem, and about 3.1% of human TB cases, up to 16% in Tanzania. Only thorough investigation to understand the pathogen's epidemiology can help in controlling the disease and minimizing its threat. For this purpose, various tools have been developed for use in advanced molecular epidemiological studies of bTB, either alone or in combination with standard conventional epidemiological approaches. These techniques enable the analysis of the intra- and inter-species transmission dynamics of bTB. The delivered data can reveal detailed insights into the source of infection, correlations among human and bovine isolates, strain diversity and evolution, spread, geographical localization, host preference, tracing of certain virulence factors such as antibiotic resistance genes, and finally the risk factors for the maintenance and spread of M. bovis. They also allow for the determination of epidemic and endemic strains. This, in turn, has a significant diagnostic impact and helps in vaccine development for bTB eradication programs. The present review discusses many topics including the aetiology, epidemiology and importance of M. bovis, the prevalence of bTB in humans and animals in various countries, the molecular epidemiology of M. bovis, and finally applied molecular epidemiological techniques.
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Affiliation(s)
- A El-Sayed
- Laboratory of Molecular Epidemiology, Faculty of Veterinary Medicine, Cairo University, Cairo, Egypt
| | - S El-Shannat
- Laboratory of Molecular Epidemiology, Faculty of Veterinary Medicine, Cairo University, Cairo, Egypt
| | - M Kamel
- Laboratory of Molecular Epidemiology, Faculty of Veterinary Medicine, Cairo University, Cairo, Egypt.,Faculty of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - M A Castañeda-Vazquez
- Laboratory of Mastitis and Molecular Diagnostic, Department of Veterinary Medicine, Division of Veterinary Sciences, University of Guadalajara, Guadalajara, Mexico
| | - H Castañeda-Vazquez
- Laboratory of Mastitis and Molecular Diagnostic, Department of Veterinary Medicine, Division of Veterinary Sciences, University of Guadalajara, Guadalajara, Mexico
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22
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Nakamura SI, Hayashidani H, Yonezawa A, Suzuki I, Une Y. Yersiniosis due to infection by Yersinia pseudotuberculosis 4b in captive meerkats (Suricata suricatta) in Japan. J Vet Diagn Invest 2015; 27:641-4. [DOI: 10.1177/1040638715596035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Two meerkats ( Suricata suricatta) housed in the same zoological garden in Japan died due to Yersinia pseudotuberculosis serotype 4b infection. Gross and microscopic lesions included necrotizing enteritis and enlargement of the spleen and liver with multifocal necrosis. Inflammatory cells, primarily neutrophils, and nuclear debris were associated with clusters of Gram-negative bacilli. Additionally, there were aberrant organism forms that were larger than bacilli and appeared as basophilic globular bodies. Immunohistochemical examination showed that the bacilli and globular bodies were strongly positive for Y. pseudotuberculosis O4 antigen. The globular bodies were considered a shape-changed form of Y. pseudotuberculosis, and these morphologically abnormal bacteria could present a diagnostic challenge.
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Affiliation(s)
- Shin-ichi Nakamura
- Laboratory of Veterinary Pathology, School of Veterinary Medicine, Azabu University, Chuo-ku, Sagamihara, Kanagawa, Japan (Nakamura, Une)
- Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan (Hayashidani)
- Himeji Central Park, Himeji, Hyogo, Japan (Yonezawa, Suzuki)
| | - Hideki Hayashidani
- Laboratory of Veterinary Pathology, School of Veterinary Medicine, Azabu University, Chuo-ku, Sagamihara, Kanagawa, Japan (Nakamura, Une)
- Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan (Hayashidani)
- Himeji Central Park, Himeji, Hyogo, Japan (Yonezawa, Suzuki)
| | - Aya Yonezawa
- Laboratory of Veterinary Pathology, School of Veterinary Medicine, Azabu University, Chuo-ku, Sagamihara, Kanagawa, Japan (Nakamura, Une)
- Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan (Hayashidani)
- Himeji Central Park, Himeji, Hyogo, Japan (Yonezawa, Suzuki)
| | - Isao Suzuki
- Laboratory of Veterinary Pathology, School of Veterinary Medicine, Azabu University, Chuo-ku, Sagamihara, Kanagawa, Japan (Nakamura, Une)
- Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan (Hayashidani)
- Himeji Central Park, Himeji, Hyogo, Japan (Yonezawa, Suzuki)
| | - Yumi Une
- Laboratory of Veterinary Pathology, School of Veterinary Medicine, Azabu University, Chuo-ku, Sagamihara, Kanagawa, Japan (Nakamura, Une)
- Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan (Hayashidani)
- Himeji Central Park, Himeji, Hyogo, Japan (Yonezawa, Suzuki)
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23
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Byrom AE, Caley P, Paterson BM, Nugent G. Feral ferrets (Mustela furo) as hosts and sentinels of tuberculosis in New Zealand. N Z Vet J 2015; 63 Suppl 1:42-53. [PMID: 25495945 PMCID: PMC4699325 DOI: 10.1080/00480169.2014.981314] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The control and eventual eradication of bovine tuberculosis (TB) poses major challenges in New Zealand, given the variety of wildlife species susceptible to TB, many of which are capable of onwards transmission of Mycobacterium bovis infection. Here we discuss the role of feral ferrets (Mustela furo), focussing on potential transmission or risk pathways that have implications for management of TB. Firstly inter-specific transmission to ferrets. Ferrets scavenge potentially infected wildlife, including other ferrets, thus prevalence of TB can be amplified through ferrets feeding on tuberculous carcasses, particularly brushtail possums (Trichosurus vulpecula). Secondly intra-specific transmission between ferrets. The rate of ferret-ferret transmission depends on population density, and in some places ferret densities exceed the estimated threshold for disease persistence. TB can therefore potentially be maintained independently of other sources of infection. Thirdly transmission from ferrets to other wildlife. These include the main wildlife maintenance host, brushtail possums, that will occasionally scavenge potentially tuberculous ferret carcasses. Fourthly transmission from ferrets to livestock. This is considered to occur occasionally, but the actual rate of transmission has never been measured. Fifthly geographical spread. M. bovis-infected ferrets can travel large distances and cause new outbreaks of TB at locations previously free of TB, which may have caused an expansion of TB-endemic areas.Ferrets play a complex role in the TB cycle in New Zealand; they are capable of contracting, amplifying and transmitting M. bovis infection, sometimes resulting in ferret populations with a high prevalence of TB. However, ferret population densities are usually too low to sustain infection independently, and transmission to other wildlife or livestock appears a rarer event than with possums. Nevertheless, management of ferrets remains a key part of the National Pest Management Strategy for TB. Control is prudent where M. bovis-infected ferret populations exist in high numbers, to reduce the onward transmission risk of any self-sustained infection to livestock. When ferret numbers are well below the theoretical disease maintenance threshold, ferret control is still sometimes warranted because of the animals’ ability to acquire infection when young and, through dispersal, transport it outside TB-endemic areas. Ferrets can also be used as disease sentinels for TB, especially in areas where alternative sentinel species are rare or expensive to survey, and when sampling of possums is not cost-effective.
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Affiliation(s)
- A E Byrom
- a Wildlife Ecology and Management Team , Landcare Research , Lincoln , New Zealand
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24
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Parsons SDC, Drewe JA, Gey van Pittius NC, Warren RM, van Helden PD. Novel cause of tuberculosis in meerkats, South Africa. Emerg Infect Dis 2014; 19:2004-7. [PMID: 24274183 PMCID: PMC3840885 DOI: 10.3201/eid1912.130268] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The organism that causes tuberculosis in meerkats (Suricata suricatta) has been poorly characterized. Our genetic analysis showed it to be a novel member of the Mycobacterium tuberculosis complex and closely related to the dassie bacillus. We have named this epidemiologically and genetically unique strain M. suricattae.
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25
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Maas M, Michel AL, Rutten VPMG. Facts and dilemmas in diagnosis of tuberculosis in wildlife. Comp Immunol Microbiol Infect Dis 2012; 36:269-85. [PMID: 23218541 DOI: 10.1016/j.cimid.2012.10.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 10/29/2012] [Accepted: 10/31/2012] [Indexed: 11/16/2022]
Abstract
Mycobacterium bovis, causing bovine tuberculosis (BTB), has been recognized as a global threat at the wildlife-livestock-human interface, a clear "One Health" issue. Several wildlife species have been identified as maintenance hosts. Spillover of infection from these species to livestock or other wildlife species may have economic and conservation implications and infection of humans causes public health concerns, especially in developing countries. Most BTB management strategies rely on BTB testing, which can be performed for a range of purposes, from disease surveillance to diagnosing individual infected animals. New diagnostic assays are being developed for selected wildlife species. This review investigates the most frequent objectives and associated requirements for testing wildlife for tuberculosis at the level of individual animals as well as small and large populations. By aligning those with the available (immunological) ante mortem diagnostic assays, the practical challenges and limitations wildlife managers and researchers are currently faced with are highlighted.
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Affiliation(s)
- M Maas
- Division of Epidemiology, Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, Utrecht, The Netherlands
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The Nexus between Bovine Tuberculosis and Fasciolosis Infections in Cattle of the Kafue Basin Ecosystem in Zambia: Implications on Abattoir Surveillance. Vet Med Int 2012; 2012:921869. [PMID: 23213629 PMCID: PMC3504483 DOI: 10.1155/2012/921869] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 10/03/2012] [Accepted: 10/10/2012] [Indexed: 11/19/2022] Open
Abstract
Bovine tuberculosis (bTB) and fasciolosis are important but neglected diseases that result in chronic infections in cattle. However, in Zambia, these diseases are mainly diagnosed at abattoirs during routine meat inspection. Albeit the coinfection status, these diseases have been reported as nothing more than normal separate findings without an explanatory phenomena. Forthwith, we formulated this study to assess the possible association of the two diseases in a known high prevalence area on the Kafue basin ecosystem. Of the 1,680 animals screened, 600 (35.7%; 95% CI 33.4%–38%) and 124 (7.4%; 95% CI 6.1%–8.6%) had fasciolosis and tuberculous lesions; respectively, whilst 72 had both fasciola and tuberculous lesions representing 12% (95% CI 9.4%–14.6%) and 58.1% (95% CI; 49.3%–66.7%) of the total positives for fasciola and tuberculosis, respectively. Jaundice was seen in 304 animals, 18.1% (95% CI; 16.3%–19.9%) and was significantly correlated to fasciolosis (r = 0.59, P < 0.0001). A significant association (χ2 = 76.2, df = 1, and P < 0.0001) was found between fasciolosis and tuberculous lesions. Simple logistic regression intimated fasciolosis as a strong predictor for tuberculous lesions with animals that had fasciola being five times more likely to have tuberculous lesions (odds ratio = 4.8, 95% CI: 3.3–7.0). This study indicates that transmission and spatial risk factors of communicable and noncommunicable diseases such as bTB and fasciolosis can be correlated in an ecosystem such as the Kafue flats.
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Nugent G, Whitford EJ, Yockney I, Perry M, Tompkins DM, Holtslag N, Cross ML. Percutaneous interdigital injection of Mycobacterium bovis as a model for tuberculous lesion development in wild brushtail possums (Trichosurus vulpecula). J Comp Pathol 2012; 148:33-42. [PMID: 22749650 DOI: 10.1016/j.jcpa.2012.05.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Revised: 05/02/2012] [Accepted: 05/07/2012] [Indexed: 10/28/2022]
Abstract
Brushtail possums (Trichosurus vulpecula) are the major wildlife reservoir of Mycobacterium bovis, the causative agent of bovine tuberculosis (BTB), in New Zealand. Primary diagnosis of BTB in wild possums is by palpation to detect peripheral lymphadenomegaly followed by necropsy examination, which frequently identifies gross tuberculous lesions in the peripheral lymph nodes and lungs. Experimental infection studies were conducted with wild possums in an attempt to emulate field BTB, focussing on percutaneous administration of virulent M. bovis in the paws. In a preliminary study, viable M. bovis bacilli were recovered from lymph nodes draining fore- or hindlimbs 12 days after percutaneous injection. Subsequently, 21 wild possums were injected interdigitally with 500 colony forming units (cfu) of M. bovis, radio-collared and released; 17/18 possums recaptured 8 weeks later had an established M. bovis lymphatic infection, with 16 having culture-positive gross lesions in the superficial and/or deep axillary lymph nodes. A dual-site infection model was established, involving simultaneous interdigital injection of 100 cfu of M. bovis into front and rear paws of 19 wild possums; this identified that the average degree of lymphadenitis involved 30-fold enlargement of the draining lymph node by 7-8 weeks post injection (wpi). A time-course study demonstrated establishment of M. bovis infection in peripheral lymph nodes of 9/11 possums at 3-5 wpi of doses ranging from 60 to 190 cfu, but with no development of gross lesions; by 7 weeks, 8/8 animals injected similarly had both an established infection and gross lesions of peripheral lymph nodes. The incidence and progression of peripheral lesion development, together with indications of sequential infection of the lungs, liver and mesenteric lymph nodes(MLNs), indicates that a low-dose percutaneous M. bovis infection model is likely to emulate natural disease in possums.
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Affiliation(s)
- G Nugent
- Landcare Research, PO Box 40, Lincoln 7640, New Zealand.
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28
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Palgrave CJ, Benato L, Eatwell K, Laurenson IF, Smith NH. Mycobacterium microti infection in two meerkats (Suricata suricatta). J Comp Pathol 2011; 146:278-82. [PMID: 21783200 DOI: 10.1016/j.jcpa.2011.06.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 06/02/2011] [Accepted: 06/03/2011] [Indexed: 11/18/2022]
Abstract
Mycobacterium microti is a member of the Mycobacterium tuberculosis complex (MTC). M. microti is generally considered a pathogen of small rodents, although sporadic infections in a range of other mammals, including domestic animals and man, have been reported. While many human infections have been associated with immunosuppression, an increasing number of cases are being reported in immunocompetent patients. Two cases of M. microti infection in meerkats (Suricata suricatta) are reported. These are the first cases of mycobacterial disease to be described in meerkats outside Africa.
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Affiliation(s)
- C J Palgrave
- Veterinary Pathology Unit, Division of Veterinary Clinical Sciences, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian EH25 9RG, UK.
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29
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Durnez L, Katakweba A, Sadiki H, Katholi CR, Kazwala RR, Machang'u RR, Portaels F, Leirs H. Mycobacteria in terrestrial small mammals on cattle farms in Tanzania. Vet Med Int 2011; 2011:495074. [PMID: 21785686 PMCID: PMC3139188 DOI: 10.4061/2011/495074] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 03/12/2011] [Accepted: 04/01/2011] [Indexed: 12/02/2022] Open
Abstract
The control of bovine tuberculosis and atypical mycobacterioses in cattle in developing countries is important but difficult because of the existence of wildlife reservoirs. In cattle farms in Tanzania, mycobacteria were detected in 7.3% of 645 small mammals and in cow's milk. The cattle farms were divided into “reacting” and “nonreacting” farms, based on tuberculin tests, and more mycobacteria were present in insectivores collected in reacting farms as compared to nonreacting farms. More mycobacteria were also present in insectivores as compared to rodents. All mycobacteria detected by culture and PCR in the small mammals were atypical mycobacteria. Analysis of the presence of mycobacteria in relation to the reactor status of the cattle farms does not exclude transmission between small mammals and cattle but indicates that transmission to cattle from another source of infection is more likely. However, because of the high prevalence of mycobacteria in some small mammal species, these infected animals can pose a risk to humans, especially in areas with a high HIV-prevalence as is the case in Tanzania.
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Affiliation(s)
- Lies Durnez
- Evolutionary Ecology Group, Department of Biology, University of Antwerp, 2020 Antwerp, Belgium
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30
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Good M, Duignan A. Perspectives on the History of Bovine TB and the Role of Tuberculin in Bovine TB Eradication. Vet Med Int 2011; 2011:410470. [PMID: 21547209 PMCID: PMC3087418 DOI: 10.4061/2011/410470] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 02/16/2011] [Indexed: 11/28/2022] Open
Abstract
Tuberculosis remains a significant disease of animals and humans worldwide. Bovine tuberculosis is caused by Mycobacteria with an extremely wide host range and serious, although currently probably underdiagnosed, zoonotic potential. Where bovine tuberculosis controls are effective, human zoonotic TB, due to Mycobacterium bovis or M. caprae, is uncommon and clinical cases are infrequent in cattle. Therefore, the control and ultimate eradication of bovine tuberculosis is desirable. Tuberculin tests are the primary screening tool used in bovine eradication. The choice of tuberculin test is dependent on the environment in which it is to be used. Tuberculin potency is critical to test performance, and the accurate determination of potency is therefore particularly important. The design of a control or eradication programme should take into consideration the fundamental scientific knowledge, the epidemiological profile of disease, the experience of other eradication programmes, and the presence, in the same ecosystem, of maintenance hosts, in which infection is self-sustaining and which are capable of transmitting infection. A control or eradication programme will necessarily require modification as it progresses and must be under constant review to identify the optimal desirable goals, the efficacy of policy, and constraints to progress.
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Affiliation(s)
- Margaret Good
- Department of Agriculture, Fisheries and Food, Agriculture House, Kildare Street, Dublin 2, Ireland
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Mycobacterium bovis at the animal–human interface: A problem, or not? Vet Microbiol 2010; 140:371-81. [DOI: 10.1016/j.vetmic.2009.08.029] [Citation(s) in RCA: 197] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 08/21/2009] [Accepted: 08/27/2009] [Indexed: 11/30/2022]
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Drewe JA. Who infects whom? Social networks and tuberculosis transmission in wild meerkats. Proc Biol Sci 2009; 277:633-42. [PMID: 19889705 DOI: 10.1098/rspb.2009.1775] [Citation(s) in RCA: 158] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Transmission of infectious diseases is strongly influenced by who contacts whom. Despite the global distribution of tuberculosis (TB) in free-living wild mammal populations, little is known of the mechanisms of social transmission of Mycobacterium bovis between individuals. Here, I use a network approach to examine for correlations between five distinct types of intra- and intergroup social interaction and changes in TB status of 110 wild meerkats (Suricata suricatta) in five social groups over two years. Contrary to predictions, the most socially interactive animals were not at highest risk of acquiring infection, indicating that in addition to contact frequency, the type and direction of interactions must be considered when quantifying disease risk. Within social groups, meerkats that groomed others most were more likely to become infected than individuals who received high levels of grooming. Conversely, receiving, but not initiating, aggression was associated with M. bovis infection. Incidence of intergroup roving by male meerkats was correlated with the rovers themselves subsequently testing TB-positive, suggesting a possible route for transmission of infection between social groups. Exposure time was less important than these social interactions in influencing TB risk. This study represents a novel application of social network analysis using empirical data to elucidate the role of specific interactions in the transmission of an infectious disease in a free-living wild animal population.
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Affiliation(s)
- Julian A Drewe
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
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