Downloaded from http://veterinaryrecord.bmj.com/ on June 28, 2015 - Published by group.bmj.com
Research
Research EDITORIAL
Feline tuberculosis caused by Mycobacterium bovis Danièlle Gunn-Moore No-one connected with farming or veterinary science could fail to know that bovine TB caused by Mycobacterium bovis is a major problem in cattle in Great Britain, especially in the west of England and Wales and, unfortunately, that its prevalence is increasing (Abernethy and others 2013). Most people are also aware that M bovis infects badgers (Gallagher and Clifton-Hadley 2000). However, people are generally less aware that in Great Britain, M bovis is now quite commonly found in cats, pigs, South American camelids (llamas and alpacas) and deer (Delahay and others 2007, Gunn-Moore and others 2011a, Broughan and others 2013), and it can be found less frequently in many other species, including dogs, goats, sheep, feral mink, ferrets, rats and mice (Delahay and others 2002, 2007, Broughan and others 2013). It is only by understanding the full complexity of M bovis ecology that we will eventually be able to control it. M bovis infection in cats is of significant importance as feline TB is being recognised with increased frequency in Great Britain (Gunn-Moore and others 2011a). Approximately 1 per cent of feline tissue samples submitted to diagnostic laboratories for routine histopathology have been found to have changes consistent Danièlle Gunn-Moore, BVMS, BSc, PhD, MACVSc, MRCVS, Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Easter Bush Midlothian EH25 9RG, Scotland, UK e-mail: [email protected]
322 | Veterinary Record | March 29, 2014
with mycobacteriosis (Gunn-Moore and others 2013) and, when cultured, M bovis is identified in 15 per cent of these samples (Gunn-Moore and others 2011a). Infected cats are almost exclusively from the west of England and Wales (Gunn-Moore and others 2011a), co-incident with the areas where cattle, badgers, mice and other small rodents are also infected (Delahay and others 2007). M bovis-infected cats are very rarely seen elsewhere in Great Britain. Unfortunately, while increasing numbers of cases of feline TB are being diagnosed, many veterinary surgeons still fail to recognise this condition. This is because, instead of presenting with wasting and a cough (as might be expected), cats with TB typically present with cutaneous lesions and/or lymphadenopathy (GunnMoore 2010). The skin lesions are single or multiple raised nodules, which may or may not be ulcerated, and/or have associated draining sinus tracts (Fig 1) (Gunn-Moore and others 2010, 2011a). Extension of granulomatous tissue may involve subcutaneous structures, muscle and/or bone, and lesions are commonly associated with either local or generalised lymphadenopathy. In some cases, local lymphadenopathy may be the only finding (Gunn-Moore and others 2011a). Chronic cases may progress to involve the lungs, with affected cats presenting with dyspnoea and, occasionally, a soft cough (Bennett and others 2011). An important piece of work on feline TB, summarised on p 326 of this issue of Veterinary Record (Roberts and others 2014), describes an unusual cluster of nine
Downloaded from http://veterinaryrecord.bmj.com/ on June 28, 2015 - Published by group.bmj.com
cats with M bovis infection, which were all presented to the same small animal practice. The clinical signs were similar to those seen in other studies, with cutaneous lesions at ‘fight and bite sites’ and/or local lymphadenopathy (four cases had popliteal lymphadenopathy), with or without pulmonary signs (seven cases had interstitial pneumonia). However, what was unusual about these cats is that they all lived in very close proximity (within 5 km; six lived within a 250 m radius). While the epidemiology of feline M bovis infection is still unclear, it is currently thought that most cats are infected when bitten by M bovis-infected small rodents while hunting (Gunn-Moore and others 2010). Rodents probably become infected when visiting contaminated badger setts; the M bovis spoligotypes found in cats are the same as those found in cattle, badgers and small rodents in any particular area (Monies and others 2006, Delahay and others 2002, 2007). Cats could also be infected via environmental contamination from infected badgers (or possibly deer), as M bovis can survive for extended periods in certain environments (Wray 1975). While it is possible that badgers could directly infect cats, this is unlikely, as they rarely interact closely. Drinking tuberculous milk is also unlikely as most cows’ milk is pasteurised in Great Britain and infected cattle are removed early in infection (as reactor cattle), so tuberculous mastitis is rarely seen. Previously, cases have been reported where a number of cats within a single household have been infected, but in most cases the cats had little close contact with each other, and the infections appeared to result from hunting the same group of infected prey (Gunn-Moore 2010). However, a small number of cases have occurred in cats that did not go outside, but that lived with another cat (or in one case a dog) that was known to be infected and/or which went outside and hunted. These cases appear to represent spread via close contact, particularly sleeping with and grooming an infected companion (Isaac and others 1983, Posthaus and others 2011, Murray and others 2014, unpublished data). Based on details in the short communication by Roberts and others (2014), it is not possible to tell how these cats were infected, but the authors suggest it was via rodents and/ or badgers. They also stated that cat-to-cat transmission could not be ruled out. Importantly, there has now been a small number of nosocomial cases, where cats naturally infected with M bovis have infected other cats via contamination within a veterinary practice, particularly during routine neutering (Murray and others 2014). All of the cats reported by Roberts and others (2014) were seen within the same small animal veterinary clinic, and one developed a tuberculous lesion at the site of
Photograph: C. Etchells
Research
FIG 1: Typical case of feline tuberculosis
castration three weeks after the operation. I have seen this startlingly rapid progression in two confirmed nosocomial cases, with clinical signs arising as soon as 14 days after ovariohysterectomy and rapid progression to the point of euthanasia at 42 days after castration (Murray and others 2014). Rapid disease progression has previously been seen in experimental (Francis 1958) and naturally occurring infections (Isaac and others 1983), and may result from a large inoculation of M bovis (Francis 1958). The information presented by Roberts and others is important as it reinforces the evidence that feline TB is now a significant disease in cats in Great Britain. It shows that infection clusters can occur, probably resulting from interactions with wildlife. It also shows that failing to recognise these infections can result in nosocomial infection. All veterinary practitioners need to know how to recognise feline TB so they do not misdiagnose it, resulting in a poor prognosis for that particular cat, while also putting themselves and their other patients at risk of M bovis-infection. Unfortunately, diagnosis is not always easy; specialist culture is the gold-standard, but it can take many weeks (Gunn-Moore and others 2011a). The interferon gamma test is proving helpful (Rhodes and others 2011), but we urgently need rapid and accurate antemortem diagnostics so that these cats can be accurately identified as quickly as possible. What we then do is up for serious debate, as while M bovis-infected cats can respond well to the correct treatment (GunnMoore and others 2011b), there are no drugs licenced for the treatment of feline TB, and although rifampicin is usually given, some people feel that this antibiotic should be kept solely for the treatment of people with TB.
References
Abernethy, D. A., Upton, P., Higgins, I. M., McGrath, G., Goodchild, A. V., Rolfe, S. J.,
Broughan, J. M. & others (2013) Bovine tuberculosis trends in the UK and the Republic of Ireland, 1995-2010. Veterinary Record doi: 10.1136/vr.100969 Bennett, A., Lalour, S., Swartz, T. & GunnMoore, D. A. (2011) Radiographic changes in cats with mycobacterial infections. Journal of Feline Medicine and Surgery 13, 718-724 Broughan, J. M., Downs, S. H., Crawshaw, T. R., Upton, P. A., Brewer, J. & CliftonHadley, R. S. (2013) Mycobacterium bovis infections in domesticated non-bovine mammalian species. Part 1: review of epidemiology and laboratory submissions in Great Britain 2004-2010. Veterinary Journal 198, 339-345 Delahay, R. J., De Leeuw, A. N., Barlow, A. M., Clifton-Hadley, R. S. & Cheeseman, C. L. (2002) The status of Mycobacterium bovis infection in UK wild mammals: a review. Veterinary Journal 164, 90-105 Delahay, R. J., Smith, G. C., Barlow, A. M., Walker, N., Harris, A., Clifton-Hadley, R. S. & Cheeseman, C. L. (2007) Bovine tuberculosis infection in wild mammals in the South-West region of England: a survey of prevalence and a semiquantitative assessment of the relative risks to cattle. Veterinary Journal 173, 287-301 Francis, J. (1958) Tuberculosis in Animals and Man: a Study in Comparative Pathology. Cassell and Company Limited. Gallagher, J. & Clifton-Hadley, R. S. (2000) Tuberculosis in badgers: a review of the disease and its significance for other animals. Research in Veterinary Science 69, 203-217 Gunn-Moore, D. A. (2010) Mycobacterial infections in cats and dogs. In Textbook of Veterinary Internal Medicine, 7th edn. Eds S. J. Ettinger, E. C. Feldman. Saunders. pp 875-881 Gunn-Moore, D. A., Dean, R. & Shaw, S. (2010) Mycobacterial infections in cats and dogs. In Practice doi: 10.1136/inp.c5313 Gunn-Moore, D. A., McFarland, S., Brewer, J., Crawshaw, T., Clifton-Hadley, R. S., Kovalik, M. & Shaw, D. J. (2011a) Mycobacterial disease in cats in Great Britain 1: bacterial species, geographical distribution and clinical presentation of 339 cases. Journal of Feline Medicine and Surgery 13, 934-944 Gunn-Moore, D. A., McFarland, S., Brewer, J., Crawshaw, T., Clifton-Hadley, R. S., Schock, A. & Shaw, D. J. (2011b) Mycobacterial disease in cats in Great Britain 2: histopathology, treatment and outcome of 339 cases. Journal of Feline Medicine and Surgery 13, 945-952 Gunn-Moore, D. A., Gaunt, C. & Shaw, D. J. (2013) Incidence of mycobacterial infections in cats in Great Britain: estimate from feline tissue samples submitted to diagnostic laboratories. Transboundary and Emerging Diseases 60, 338-344 Isaac, J., Whitehead, J., Adams, J. W., Barton, M. D. & Coloe, P. (1983) An outbreak of Mycobacterium bovis infection in cats in an animal house. Australian Veterinary Journal 60, 243-245 Monies, B., Jahans, K. & de la Rue, R. (2006) Bovine tuberculosis in cats. Veterinary Record 158, 245-256 Murray, A., Dineen, A., Kelly, P., McGoey, K., Madigan, G., NiGhallchoir, D. & Gunn-Moore, D. A. (2014) Nosocomial spread of Mycobacterium bovis in domestic cats. Journal of Feline Medicine and Surgery, (In press) Posthaus, H., Bodmer, T., Alves, L., Oevermann, A., Schiller, I., Rhodes, S. G. & Zimmerli, S. (2011) Accidental infection of veterinary personnel with Mycobacterium tuberculosis at necropsy: a case study. Veterinary Microbiology 149, 374-380 Rhodes, S. G., Gunn-Moore, D. A., Boschiroli, L., Schiller, I., Esfandiari, J., Greenwalr, R. & Lyashchenko, K. P. (2011) Comparative study of IFNγ and antibody tests for feline tuberculosis. Veterinary Immunology and Immunopathology 144, 129-134 Roberts, T., O’Connor, C., Nuñez-Garcia, J., de la Rua-Domenech, R. & Smith, N. H. (2014) Unusual cluster of Mycobacterium bovis infection in cats. Veterinary Record doi: 10.1136/vr.102457 Wray, C. (1975) Survival and spread of pathogenic bacteria of veterinary importance within the environment. Veterinary Bulletin 45, 543-550
doi: 10.1136/vr.g2338 March 29, 2014 | Veterinary Record | 323
Downloaded from http://veterinaryrecord.bmj.com/ on June 28, 2015 - Published by group.bmj.com
Feline tuberculosis caused by Mycobacterium bovis Danièlle Gunn-Moore Veterinary Record 2014 174: 322-323
doi: 10.1136/vr.g2338 Updated information and services can be found at: http://veterinaryrecord.bmj.com/content/174/13/322
These include:
References Email alerting service
This article cites 12 articles, 4 of which you can access for free at: http://veterinaryrecord.bmj.com/content/174/13/322#BIBL Receive free email alerts when new articles cite this article. Sign up in the box at the top right corner of the online article.
Notes
To request permissions go to: http://group.bmj.com/group/rights-licensing/permissions To order reprints go to: http://journals.bmj.com/cgi/reprintform To subscribe to BMJ go to: http://group.bmj.com/subscribe/
Research
Research EDITORIAL
Feline tuberculosis caused by Mycobacterium bovis Danièlle Gunn-Moore No-one connected with farming or veterinary science could fail to know that bovine TB caused by Mycobacterium bovis is a major problem in cattle in Great Britain, especially in the west of England and Wales and, unfortunately, that its prevalence is increasing (Abernethy and others 2013). Most people are also aware that M bovis infects badgers (Gallagher and Clifton-Hadley 2000). However, people are generally less aware that in Great Britain, M bovis is now quite commonly found in cats, pigs, South American camelids (llamas and alpacas) and deer (Delahay and others 2007, Gunn-Moore and others 2011a, Broughan and others 2013), and it can be found less frequently in many other species, including dogs, goats, sheep, feral mink, ferrets, rats and mice (Delahay and others 2002, 2007, Broughan and others 2013). It is only by understanding the full complexity of M bovis ecology that we will eventually be able to control it. M bovis infection in cats is of significant importance as feline TB is being recognised with increased frequency in Great Britain (Gunn-Moore and others 2011a). Approximately 1 per cent of feline tissue samples submitted to diagnostic laboratories for routine histopathology have been found to have changes consistent Danièlle Gunn-Moore, BVMS, BSc, PhD, MACVSc, MRCVS, Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Easter Bush Midlothian EH25 9RG, Scotland, UK e-mail: [email protected]
322 | Veterinary Record | March 29, 2014
with mycobacteriosis (Gunn-Moore and others 2013) and, when cultured, M bovis is identified in 15 per cent of these samples (Gunn-Moore and others 2011a). Infected cats are almost exclusively from the west of England and Wales (Gunn-Moore and others 2011a), co-incident with the areas where cattle, badgers, mice and other small rodents are also infected (Delahay and others 2007). M bovis-infected cats are very rarely seen elsewhere in Great Britain. Unfortunately, while increasing numbers of cases of feline TB are being diagnosed, many veterinary surgeons still fail to recognise this condition. This is because, instead of presenting with wasting and a cough (as might be expected), cats with TB typically present with cutaneous lesions and/or lymphadenopathy (GunnMoore 2010). The skin lesions are single or multiple raised nodules, which may or may not be ulcerated, and/or have associated draining sinus tracts (Fig 1) (Gunn-Moore and others 2010, 2011a). Extension of granulomatous tissue may involve subcutaneous structures, muscle and/or bone, and lesions are commonly associated with either local or generalised lymphadenopathy. In some cases, local lymphadenopathy may be the only finding (Gunn-Moore and others 2011a). Chronic cases may progress to involve the lungs, with affected cats presenting with dyspnoea and, occasionally, a soft cough (Bennett and others 2011). An important piece of work on feline TB, summarised on p 326 of this issue of Veterinary Record (Roberts and others 2014), describes an unusual cluster of nine
Downloaded from http://veterinaryrecord.bmj.com/ on June 28, 2015 - Published by group.bmj.com
cats with M bovis infection, which were all presented to the same small animal practice. The clinical signs were similar to those seen in other studies, with cutaneous lesions at ‘fight and bite sites’ and/or local lymphadenopathy (four cases had popliteal lymphadenopathy), with or without pulmonary signs (seven cases had interstitial pneumonia). However, what was unusual about these cats is that they all lived in very close proximity (within 5 km; six lived within a 250 m radius). While the epidemiology of feline M bovis infection is still unclear, it is currently thought that most cats are infected when bitten by M bovis-infected small rodents while hunting (Gunn-Moore and others 2010). Rodents probably become infected when visiting contaminated badger setts; the M bovis spoligotypes found in cats are the same as those found in cattle, badgers and small rodents in any particular area (Monies and others 2006, Delahay and others 2002, 2007). Cats could also be infected via environmental contamination from infected badgers (or possibly deer), as M bovis can survive for extended periods in certain environments (Wray 1975). While it is possible that badgers could directly infect cats, this is unlikely, as they rarely interact closely. Drinking tuberculous milk is also unlikely as most cows’ milk is pasteurised in Great Britain and infected cattle are removed early in infection (as reactor cattle), so tuberculous mastitis is rarely seen. Previously, cases have been reported where a number of cats within a single household have been infected, but in most cases the cats had little close contact with each other, and the infections appeared to result from hunting the same group of infected prey (Gunn-Moore 2010). However, a small number of cases have occurred in cats that did not go outside, but that lived with another cat (or in one case a dog) that was known to be infected and/or which went outside and hunted. These cases appear to represent spread via close contact, particularly sleeping with and grooming an infected companion (Isaac and others 1983, Posthaus and others 2011, Murray and others 2014, unpublished data). Based on details in the short communication by Roberts and others (2014), it is not possible to tell how these cats were infected, but the authors suggest it was via rodents and/ or badgers. They also stated that cat-to-cat transmission could not be ruled out. Importantly, there has now been a small number of nosocomial cases, where cats naturally infected with M bovis have infected other cats via contamination within a veterinary practice, particularly during routine neutering (Murray and others 2014). All of the cats reported by Roberts and others (2014) were seen within the same small animal veterinary clinic, and one developed a tuberculous lesion at the site of
Photograph: C. Etchells
Research
FIG 1: Typical case of feline tuberculosis
castration three weeks after the operation. I have seen this startlingly rapid progression in two confirmed nosocomial cases, with clinical signs arising as soon as 14 days after ovariohysterectomy and rapid progression to the point of euthanasia at 42 days after castration (Murray and others 2014). Rapid disease progression has previously been seen in experimental (Francis 1958) and naturally occurring infections (Isaac and others 1983), and may result from a large inoculation of M bovis (Francis 1958). The information presented by Roberts and others is important as it reinforces the evidence that feline TB is now a significant disease in cats in Great Britain. It shows that infection clusters can occur, probably resulting from interactions with wildlife. It also shows that failing to recognise these infections can result in nosocomial infection. All veterinary practitioners need to know how to recognise feline TB so they do not misdiagnose it, resulting in a poor prognosis for that particular cat, while also putting themselves and their other patients at risk of M bovis-infection. Unfortunately, diagnosis is not always easy; specialist culture is the gold-standard, but it can take many weeks (Gunn-Moore and others 2011a). The interferon gamma test is proving helpful (Rhodes and others 2011), but we urgently need rapid and accurate antemortem diagnostics so that these cats can be accurately identified as quickly as possible. What we then do is up for serious debate, as while M bovis-infected cats can respond well to the correct treatment (GunnMoore and others 2011b), there are no drugs licenced for the treatment of feline TB, and although rifampicin is usually given, some people feel that this antibiotic should be kept solely for the treatment of people with TB.
References
Abernethy, D. A., Upton, P., Higgins, I. M., McGrath, G., Goodchild, A. V., Rolfe, S. J.,
Broughan, J. M. & others (2013) Bovine tuberculosis trends in the UK and the Republic of Ireland, 1995-2010. Veterinary Record doi: 10.1136/vr.100969 Bennett, A., Lalour, S., Swartz, T. & GunnMoore, D. A. (2011) Radiographic changes in cats with mycobacterial infections. Journal of Feline Medicine and Surgery 13, 718-724 Broughan, J. M., Downs, S. H., Crawshaw, T. R., Upton, P. A., Brewer, J. & CliftonHadley, R. S. (2013) Mycobacterium bovis infections in domesticated non-bovine mammalian species. Part 1: review of epidemiology and laboratory submissions in Great Britain 2004-2010. Veterinary Journal 198, 339-345 Delahay, R. J., De Leeuw, A. N., Barlow, A. M., Clifton-Hadley, R. S. & Cheeseman, C. L. (2002) The status of Mycobacterium bovis infection in UK wild mammals: a review. Veterinary Journal 164, 90-105 Delahay, R. J., Smith, G. C., Barlow, A. M., Walker, N., Harris, A., Clifton-Hadley, R. S. & Cheeseman, C. L. (2007) Bovine tuberculosis infection in wild mammals in the South-West region of England: a survey of prevalence and a semiquantitative assessment of the relative risks to cattle. Veterinary Journal 173, 287-301 Francis, J. (1958) Tuberculosis in Animals and Man: a Study in Comparative Pathology. Cassell and Company Limited. Gallagher, J. & Clifton-Hadley, R. S. (2000) Tuberculosis in badgers: a review of the disease and its significance for other animals. Research in Veterinary Science 69, 203-217 Gunn-Moore, D. A. (2010) Mycobacterial infections in cats and dogs. In Textbook of Veterinary Internal Medicine, 7th edn. Eds S. J. Ettinger, E. C. Feldman. Saunders. pp 875-881 Gunn-Moore, D. A., Dean, R. & Shaw, S. (2010) Mycobacterial infections in cats and dogs. In Practice doi: 10.1136/inp.c5313 Gunn-Moore, D. A., McFarland, S., Brewer, J., Crawshaw, T., Clifton-Hadley, R. S., Kovalik, M. & Shaw, D. J. (2011a) Mycobacterial disease in cats in Great Britain 1: bacterial species, geographical distribution and clinical presentation of 339 cases. Journal of Feline Medicine and Surgery 13, 934-944 Gunn-Moore, D. A., McFarland, S., Brewer, J., Crawshaw, T., Clifton-Hadley, R. S., Schock, A. & Shaw, D. J. (2011b) Mycobacterial disease in cats in Great Britain 2: histopathology, treatment and outcome of 339 cases. Journal of Feline Medicine and Surgery 13, 945-952 Gunn-Moore, D. A., Gaunt, C. & Shaw, D. J. (2013) Incidence of mycobacterial infections in cats in Great Britain: estimate from feline tissue samples submitted to diagnostic laboratories. Transboundary and Emerging Diseases 60, 338-344 Isaac, J., Whitehead, J., Adams, J. W., Barton, M. D. & Coloe, P. (1983) An outbreak of Mycobacterium bovis infection in cats in an animal house. Australian Veterinary Journal 60, 243-245 Monies, B., Jahans, K. & de la Rue, R. (2006) Bovine tuberculosis in cats. Veterinary Record 158, 245-256 Murray, A., Dineen, A., Kelly, P., McGoey, K., Madigan, G., NiGhallchoir, D. & Gunn-Moore, D. A. (2014) Nosocomial spread of Mycobacterium bovis in domestic cats. Journal of Feline Medicine and Surgery, (In press) Posthaus, H., Bodmer, T., Alves, L., Oevermann, A., Schiller, I., Rhodes, S. G. & Zimmerli, S. (2011) Accidental infection of veterinary personnel with Mycobacterium tuberculosis at necropsy: a case study. Veterinary Microbiology 149, 374-380 Rhodes, S. G., Gunn-Moore, D. A., Boschiroli, L., Schiller, I., Esfandiari, J., Greenwalr, R. & Lyashchenko, K. P. (2011) Comparative study of IFNγ and antibody tests for feline tuberculosis. Veterinary Immunology and Immunopathology 144, 129-134 Roberts, T., O’Connor, C., Nuñez-Garcia, J., de la Rua-Domenech, R. & Smith, N. H. (2014) Unusual cluster of Mycobacterium bovis infection in cats. Veterinary Record doi: 10.1136/vr.102457 Wray, C. (1975) Survival and spread of pathogenic bacteria of veterinary importance within the environment. Veterinary Bulletin 45, 543-550
doi: 10.1136/vr.g2338 March 29, 2014 | Veterinary Record | 323
Downloaded from http://veterinaryrecord.bmj.com/ on June 28, 2015 - Published by group.bmj.com
Feline tuberculosis caused by Mycobacterium bovis Danièlle Gunn-Moore Veterinary Record 2014 174: 322-323
doi: 10.1136/vr.g2338 Updated information and services can be found at: http://veterinaryrecord.bmj.com/content/174/13/322
These include:
References Email alerting service
This article cites 12 articles, 4 of which you can access for free at: http://veterinaryrecord.bmj.com/content/174/13/322#BIBL Receive free email alerts when new articles cite this article. Sign up in the box at the top right corner of the online article.
Notes
To request permissions go to: http://group.bmj.com/group/rights-licensing/permissions To order reprints go to: http://journals.bmj.com/cgi/reprintform To subscribe to BMJ go to: http://group.bmj.com/subscribe/
