§ Mr. PatersonTo ask the Secretary of State for Environment, Food and Rural Affairs how long mycobacterium bovis bacilli can survive on open pasture; and under what conditions.[141395]
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§ Mr. BradshawMycobacterium bovis may be present within a variety of media on open pasture, each influencing the survival of the bas cilli. In cow manure M. bovis may survive for up to four months in autumn, five months in winter and two months in spring, dependent on concentration. Greater concentrations promote survival.
When exposed to sunlight at 24–34 degrees celsius M. bovis has survived for 5–11 months in manure at pasture. Survival in samples buried in 1cm deep pits has been up to one year and at 5cm deep up to two years.
M. bovis can be highly concentrated in badger urine and can survive for over a week on open pasture during the winter but very few bacilli survive after four weeks. During the summer survival can reduce to less than three days in badger urine.
M. bovis in badger bronchial pus and sputum can survive for up to 10 weeks on open pasture in winter but less than one week in summer. Survival in badger faeces can be for up to one month during the winter but less than two weeks in summer.
Survival may also be influenced by the presence of other microorganisms in the environment. Fungi, algae, protozoans and many other bacteria compete with M. bovis for nutrients, may have greater growth rates, and may produce natural antibiotics.
§ Mr. PatersonTo ask the Secretary of State for Environment, Food and Rural Affairs how many TB reactor cattle were reported to her Department and its predecessors,(a) in each year from 1990 to 2002 and (b) from 1 January to 31 October; how many were subject to culture testing; and how many proved TB positive on culture.[142468]
§ Mr. BradshawTable 1 shows the number of TB reactors, how many were subject to culture for Mycobacterium bovis, and the number successfully cultured for the years 1990–2002 in Great Britain.
Table 2 gives provisional data for the number of TB reactors, the number subject to culture, and the number successfully cultured for Mycobacterium bovis in Great Britain for 2003 (till end of October).
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Table 1 GB Figures Number of TB Reactors
Number Subject To Culture Testing
TB Positive on Culture 1990 719 4 1— 1991 1,050 4 1— 1992 1,086 l— 1— 1993 1,814 2 l— 1994 2,248 515 238 1995 2,861 2,492 1,051 1996 3,296 2,852 1,163 1997 3,358 3,005 1,196 1998 5,063 4,121 1,645 1999 6,047 4,894 2,033 2000 7,143 5,456 2,550 2001 5,472 3,818 1,447 2002 20,053 14,102 2,557 1— Data not available
Table 2 2003 GB Figures (provisional) January to October 2003 Number of TB Reactors 17,589 Number Subject To Culture 12,228 TB Positive on Culture 2,681
§ Mr. DrewTo ask the Secretary of State for Environment, Food and Rural Affairs how many badgers were culled in each reactive area as part of the Independent Science Group study into bovine TB.[144928]
§ Mr. BradshawThe table lists the numbers of badgers culled in the reactive treatment areas of the Randomised Badger Culling Trial.
Numbers of badgers culled in reactive treatment areas of randomised badger culling trial Triplet Name of reactive treatment area
Number of badgers culled
A Blaisdon 117 B Hartland 301 C Otterham 394 D Puddlestone 122 E Cold Ashton 188 F Stithians 435 G Nettley Knowle 256 H Brendon Hills 159 I Alderton 94 J Cadbury 0
§ Mr. PatersonTo ask the Secretary of State for Environment, Food and Rural Affairs what plans she has for post movement testing of cattle for exposure to M.bovis; and what assessment she has made of the implications of such testing(a) within four months of movement and (b) by the date of the next due test of the herd from which the animal came. [144436]
§ Mr. BradshawAll farmers have been sent a leaflet "Golden rules for a healthy herd", which advises purchasers to check the disease status of cattle prior to purchase and to consider arranging a private TB test for their herd.
In February 2003, the Secretary of State for Environment, Food and Rural Affairs announced a review of our bovine tuberculosis strategy. Early in the new year we will be publishing a consultation document which will represent the outcome of the first stage of that review. The consultation document will include proposals for short term measures for reducing the risk of geographic spread of bovine TB from high to low incidence areas, including consideration of proposals for the pre and/or post movement testing of cattle.
When considering post-movement testing of cattle sold from farm to farm, we have envisaged that, as a general rule, such tests would be administered between 60 and 120 days after movement (i.e. 2–4 months post movement). This is to ensure that a minimum of 60 days have elapsed since the last test and since any potential exposure to M.bovis on the premises of origin, to avoid problems of de-sensitisation caused by recent testing and to allow for the normal delay in the development of a response to the skin test. Knowledge of whether a pre-movement test had taken place and when, would allow the post movement test to be better targeted.
249W Assuming post-movement testing is carried out as outlined, the date of the next due test of the herd of origin need not be considered.
§ Mr. PatersonTo ask the Secretary of State for Environment, Food and Rural Affairs what the recognised minimum time required is from exposure of cattle to M.bovis to an immune response which will show in the skin test used by her Department. [144437]
§ Mr. BradshawThe immune response elicited by Mycobacterium bovis in cattle takes several weeks to develop to a stage where it is detectable. For the single intradermal comparative test used in the UK and Ireland, this period of "unresponsiveness" or latency varies between 30 and 50 days.
To allow for random and natural variation in the latency period of individual animals, the legislation requires repeat testing to be carried out at intervals of at least 60 days from the date of the removal (or isolation) of all the reactors identified at the previous skin test.
§ Mr. PatersonTo ask the Secretary of State for Environment, Food and Rural Affairs what significant variations in incubation period have been observed in herd breakdowns involving several cattle reactors resulting from infection with M.bovis.[144439]
§ Mr. BradshawMany factors influence the progression of Mycobacterium bovis, infection into detectable disease, including the strain of the bacterium, size of bacterial challenge and route of infection. Other factors include affected animal (species, breed, genotype, age) or the effects of its environment (nutritional status, stress, other infections and environmental bacteria).
§ Mr. PatersonTo ask the Secretary of State for Environment, Food and Rural Affairs how many strains of M.bovis have been found in(a) cattle and (b) badgers in the UK; and what assessment has been made of the virulence of each strain.[144440]
§ Mr. BradshawM.bovis isolates are routinely typed using a DNA fingerprinting technique called spoligotyping. In Great Britain 30 different spoligotypes have been identified in cattle and in 16 badgers. Of those in cattle, 12 of those account for 99 per cent. of the isolates.
§ Mr. PatersonTo ask the Secretary of State for Environment, Food and Rural Affairs what assessment she has made of whether development of lesions in cattle following exposure to M.bovis is the result of(a) a more virulent strain, (b) the level of infective dose and (c) the frequency of the infective dose. [144441]
§ Mr. BradshawThe pathogenesis of bovine TB is not yet fully understood. As a result, Defra is funding several research projects into the pathogenesis and immunology of the disease.
§ Mr. PatersonTo ask the Secretary of State for Environment, Food and Rural Affairs what the average length of herd breakdown was in(a) 2002–03 and (b) 1998; how many 60 day tests were needed to clear (i) suspect and (ii) infected herds in each year; and what the cost of the tests were.[144442]
§ Mr. BradshawThe information is as follows:250W
Information on the cost of tests needed to clear unconfirmed and confirmed herd incidents in each year is not readily available and can be obtained only at a disproportionate cost.
- (a) The average duration of TB incidents ending in 2002 was skewed by those herds already restricted when TB testing was suspended during the foot and mouth disease outbreak of 2001. The figures for TB incidents ending in 2002 (the last year for which statistics are available) were as follows: unconfirmed incidents—149 days; confirmed incident—291 days.
- The mean length of unconfirmed new TB incidents (herd breakdowns) ending in 1998 was 114 days, i.e. slightly less than two short interval (60-day) tests. In the same year, the mean length of confirmed new incidents was 208 days.
§ Mr. PatersonTo ask the Secretary of State for Environment, Food and Rural Affairs what proportion of badgers which appeared TB free in post-mortem examination were culture positive to M.bovis, in the last year for which figures are available.[144443]
§ Mr. BradshawThe last year for which data are available is 1999. These are from Badger Removal Operations and the Road Traffic Accident (RTA) survey that predate the Randomised Badger Culling Trial and associated RTA survey.
In 1999, 874 badger carcasses were considered suitable for post-mortem examination. 753 displayed no visible lesions suggestive of TB. Mycobacterium bovis was isolated in 54 of these.
Therefore, the proportion appearing TB free at postmortem, but culture positive for m. bovis is 7.2 per cent.
§ Mr. PatersonTo ask the Secretary of State for Environment, Food and Rural Affairs what proportion of cattle showed no visible lesions in post mortem examination but were culture positive for M.bovis, in the last year for which figures are available.[144444]
§ Mr. BradshawLast year, 6,600 samples were sent for laboratory culture after no visible lesions were found at post mortem. Mycobacterium bovis was successfully cultured in 5.6 per cent. of these.