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Mycobacterium bovis (Bovine TB)

 

General Information

Mycobacterium bovis (M. bovis) is one of the species in the Mycobacterium tuberculosis complex, a group of closely related organisms which are causative agents of tuberculosis in humans. In the UK, the current risk posed by M. bovis to human health is considered very small with the majority of TB cases caused by the tubercle bacillus Mycobacterium tuberculosis. More information about TB in Wales is available from the webpage on tuberculosis at: http://www.wales.nhs.uk/sites3/page.cfm?orgid=457&pid=27952
 
M. bovis can be found in a broad range of wild and domestic animals, that act as potential reservoirs for human infection. Human infection generally results from contact with infected animals although human to human transmission can occur albeit rarely. Historically, transmission was most commonly through the ingestion of milk and meat from infected animals. The link between drinking milk from diseased cows and the development of scrofula, cervical lymph node tuberculosis, was established mid-19th century when more than half of all cervical lymphadenitis cases in children were caused by M. bovis.  
  
It is not possible to clinically differentiate between TB caused by M. bovis and that caused by M. tuberculosis. The course and extent of the disease is the same, as is the treatment in most cases. However, M. bovis human infection usually results from ingestions of contaminated milk, and is therefore characterised by cervical lymphadenopathy due to infection of milk-borne bacilli in the tonsils and pharynx.  More information about M. bovis is available from the Health Protection Agency website at:  http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/Tuberculosis/GeneralInformation/TBgen04Mbovis/
 
 

UK Mycobacterium Surveillance

An enhanced surveillance system for Mycobacterium bovis in humans was implemented by the Health Protection Agency (HPA) in 1999 to complement the existing mycobacterial isolate surveillance system (Mycobnet), which collects data from UK reference laboratories including the Wales Centre for Mycobacteria (WCM) in Cardiff.  The enhanced surveillance of M. bovis allows further epidemiological data to be collected, with one specific aim being to look for possible farming links. 
 
 

Data for Wales 2001-2010

Tuberculosis caused by M. bovis: Cases and rates in Wales 2001-2010
 
 
 
        m. bovis rate wales 2010
 
 
Tuberculosis caused by M. bovis: Cases and rates in the UK 2001-2010
  
 
England
Wales
Scotland
N. Ireland
Year
Number of cases
Rate per 100,000 population
Number of cases
Rate per 100,000 population
Number of cases
Rate per 100,000 population
Number of cases
Rate per 100,000 population
2001
24
0.05
6
0.21
2
0.04
1
0.06
2002
17
0.03
1
0.03
1
0.02
0
0
2003
15
0.03
0
0
4
0.08
2
0.12
2004
14
0.03
1
0.03
4
0.08
2
0.12
2005
24
0.05
4
0.14
4
0.08
7
0.41
2006
26
0.05
0
0
5
0.10
2
0.11
2007
23
0.05
2
0.07
1
0.02
1
0.06
2008
22
0.04
2
0.07
2
0.04
3
0.17
2009
25
0.05
5
0.17
7
0.13
1
0.06
2010
22
0.04
1
0.03
0
0
1
0.06
 
 
Tuberculosis caused by M. bovis: Rates in the UK 2001-2010
 
 
Tuberculosis caused by M. bovis: Cases
and rates in Wales by age 2001-2010
 
Age group (years)
Number of cases
Rate per 100,000 population
0-4
0
0
5-14
0
0
15-24
2
0.51
25-34
1
0.29
35-44
1
0.24
45-54
3
0.77
55-64
2
0.54
65+
12
2.28
Unknown
1
0
Source: M. bovis database, HPA 
 
Tuberculosis caused by M. bovis: Cases
and rates in Wales by gender 2001-2010
 
Gender
Number of cases
Rate per 100,000 population
Male
9
0.62
Female
12
0.79
Unknown
1
0.51
Source: M. bovis database, HPA 
 
 
 
 
 
 
 
 
 
 
 
Tuberculosis caused by M. bovis:
Site of infection 2001-2010
 
Site
Number of cases
Pulmonary
8
Abdomen
1
Renal
1
Lymph
3
CNS
1
Extrapulmonary
3
Unknown
5
Source: M. bovis database, HPA 
 
 
 
 
 
 
 

Epidemiology

Current rate of tuberculosis in the UK caused by M. bovis are  negligible due to effective controls through milk pasteurisation and tuberculin screening of herds to identify infected animals. Prior to the introduction of these control measures infection with M. bovis was much more common with an estimated 6% of tuberculosis deaths in England and Wales during the 1930s due to M. bovis infection.
 
Nowadays the majority of TB cases attributed to M. bovis in the UK are due to reactivation of latent TB infection, acquired originallyas a consequence of consumption of milk prior to widespread pasteurisation.  As a result, the majority of cases occur in the older population. Infection can also be acquired abroad or due to occupational exposure e.g. those who work in the agricultural industry. 
 
Twenty-two cases of tuberculosis caused by infection with M. bovis have been identified in Wales between 2001-2010 and of these 59% (13/22) were born in the UK and 64% (14/22) were aged 55 years and over. Of the 22 cases, three (14%) reported known contact with individuals known to have TB and eight had previously consumed unpasteurised milk.
 
 

Requests for further surveillance data

If further surveillance data for M. bovis in Wales are required, it may be possible to provide it on special request. Please use the surveillance data request form provided from this link.
 
 

Links to further information

Animal health and welfare
Human health
 
 
 


Last updated: 06/02/2012