Zoonotic TB - Human Mycobacterium bovis infection in the United Kingdom

[Gert van der Hoek]

Re: Zoonotic TB - Human Mycobacterium bovis infection in the United Kingdom

See also: http://www.flutrackers.com/forum/sho...d.php?t=194004


Badger cull: government accused of failing to properly seek alternatives

Scientist John Bourne, who led landmark 10-year cull, says it is cattle that spread TB through the country, not badgers

Damian Carrington

guardian.co.uk, Monday 15 October 2012



Ministers are going "nowhere near far enough" in seeking alternatives to the imminent cull of badgers, according the scientist who led the landmark 10-year culling trial that remains the scientific benchmark for the policy.

According to Prof John Bourne, stricter measures to stop cows spreading tuberculoisis to other cows are the only way to combat the disease effectively, as they had in the 1960s when TB was virtually eradicated in England.

"Despite some improvements, the government is still going nowhere near far enough with biosecurity", he said. "It is not badgers that spread the disease throughout the country; it is cattle".

More: The Guardian

[Gert van der Hoek]

Re: Zoonotic TB - Human Mycobacterium bovis infection in the United Kingdom

More threads regarding Bovine TB in the UK and Ireland:

http://www.flutrackers.com/forum/showthread.php?t=15228

http://www.flutrackers.com/forum/showthread.php?t=152062

[Gert van der Hoek]

Re: Zoonotic TB - Human Mycobacterium bovis infection in the United Kingdom

In the UK researchers are trying to find a way to vaccinate badgers, which seem to be a reservoir for bovine TB. Culling badgers seems to make things worse. Bovine TB can have significant consequences for public health.

J Wildl Dis. 2009 Jan;45(1):128-43.

Bovine tuberculosis in cattle and badgers in localized culling areas.



Abstract

Bovine tuberculosis (TB) is a zoonotic disease that can have serious consequences for cattle farming and, potentially, for public health. In Britain, failure to control bovine TB has been linked to persistent infection of European badger (Meles meles) populations. However, culling of badgers in the vicinity of recent TB outbreaks in cattle has failed to reduce the overall incidence of cattle TB.

Using data from a large-scale study conducted in 1998-2005, we show that badgers collected on such localized culls had elevated prevalence of Mycobacterium bovis, the causative agent of bovine TB, suggesting that infections in cattle and badgers were indeed associated. Moreover, there was a high degree of similarity in the M. bovis strain types isolated from cattle and associated badgers.

This similarity between strain types appeared to be unaffected by time lags between the detection of infection in cattle and culling of badgers, or by the presence of purchased cattle that might have acquired infection elsewhere. However, localized culling appeared to prompt an increase in the prevalence of M. bovis infection in badgers, probably by disrupting ranging and territorial behavior and hence increasing intraspecific transmission rates.

This elevated prevalence among badgers could offset the benefits, for cattle, of reduced badger densities and may help to explain the failure of localized culling to reduce cattle TB incidence.

PubMED

[Gert van der Hoek]

Bovine TB could be underreported in many countries, incl. the UK. Currently the UK has a major bovine TB problem.


Tuberculosis (Edinb). 2006 Mar;86(2):77-109. Epub 2005 Oct 28.

Human Mycobacterium bovis infection in the United Kingdom:
Incidence, risks, control measures and review of the zoonotic aspects of bovine tuberculosis.


Abstract
Amongst the members of the Mycobacterium tuberculosis complex (MTBC), M. tuberculosis is mainly a human pathogen, whereas M. bovis has a broad host range and is the principal agent responsible for tuberculosis (TB) in domestic and wild mammals.

M. bovis also infects humans, causing zoonotic TB through ingestion, inhalation and, less frequently, by contact with mucous membranes and broken skin. Zoonotic TB is indistinguishable clinically or pathologically from TB caused by M. tuberculosis.

Differentiation between the causative organisms may only be achieved by sophisticated laboratory methods involving bacteriological culture of clinical specimens, followed by typing of isolates according to growth characteristics, biochemical properties, routine resistance to pyrazinamide (PZA) and specific non-commercial nucleic acid techniques.

All this makes it difficult to accurately estimate the proportion of human TB cases caused by M. bovis infection, particularly in developing countries. Distinguishing between the various members of the MTBC is essential for epidemiological investigation of human cases and, to a lesser degree, for adequate chemotherapy of the human TB patient.

Zoonotic TB was formerly an endemic disease in the UK population, usually transmitted to man by consumption of raw cows' milk. Human infection with M. bovis in the UK has been largely controlled through pasteurization of cows' milk and systematic culling of cattle reacting to compulsory tuberculin tests.

Nowadays the majority of the 7000 cases of human TB annually reported in the UK are due to M. tuberculosis acquired directly from an infectious person. In the period 1990-2003, between 17 and 50 new cases of human M. bovis infection were confirmed every year in the UK. This represented between 0.5% and 1.5% of all the culture-confirmed TB cases, a proportion similar to that of other industrialized countries.

Most cases of zoonotic TB diagnosed in the UK are attributed to (i) reactivation of long-standing latent infections acquired before widespread adoption of milk pasteurization, or (ii) M. bovis infections contracted abroad.

Since 1990, only one case has been documented in the UK of confirmed, indigenous human M. bovis infection recently acquired from an animal source. Therefore, for the overwhelming majority of the population, the risk of contracting M. bovis infection from animals appears to be extremely low. However, bovine TB is once again a major animal health problem in the UK.

Given the increasing numbers of cattle herds being affected each year, physicians and other public health professionals must remember that zoonotic TB is not just a disease of the past.

A significant risk of M. bovis infection remains in certain segments of the UK population in the form of (i) continuing on-farm consumption of unpasteurized cows' milk, (ii) retail sales by approved establishments of unpasteurized milk and dairy products and (iii) occupational exposure to infectious aerosols from tuberculous animals and their carcases.

PubMED