Clicky

 

Ways in which New Zealand has reduced bovine TB

This site requires Javascript.
 You have Javascript disabled.

TB prevalence in Great Britain and New Zealand cattle

In New Zealand in 1990 the proportion of TB in cattle was about 7 times greater than it was in Great Britain. However in 1997 the proportions were about equal. Currently (in 2011) the proportion in New Zealand is about 40 times less than what it is in Great Britain. Since the early nineties, control of the principal wildlife vector, the possum, in New Zealand has increased whilst in Great Britain since 1986 control of the principal wildlife vector, the badger, has reduced.

TB prevalence in Great Britain and New Zealand

In the above plot, data was sourced as follows.

Great BritainRequest
Request
Reply
Reply
(See reply)
Received data
New ZealandRequestReplyReceived data

The proportion of cattle slaughtered was calculated by dividing the number of TB reactors by the total number of cattle which existed in that year. Cattle numbers for each year in Great Britain before 1998 were taken from Reference 21.

TB infected herds in Great Britain and New Zealand


Number of bovine TB infected herds in Great Britain and New Zealand

In the above plot, data for Great Britain were supplied by DEFRA and were extracted from AHVLA Chief Veterinary Officer's reports from 1967 to 1994, TB incidents in Great Britain, county herd statistics, and detailed TB statistics.

Data for New Zealand were supplied by the Technical Manager of New Zealand's Animal Health Board (AHB) and were extracted from this spreadsheet.

In New Zealand data, the year is financial (starting 1st July), and in the above plots the year refers to the year in which the financial year ends. In Great Britain data, the year is the calendar year, starting 1st January, so when comparing data between the 2 countries there is a 6-month offset.

Great Britain milestones

  • 1960 Great Britain gained attested status for cattle testing
    The whole of Great Britain became attested on 1st October 1960 (i.e. each cattle herd was certified as being subject to regular tuberculin testing with immediate slaughter of any reactors). Progress was maintained throughout the 1960s and 1970s. Unfortunately, the progressive reduction in TB incidence stalled in the mid-1980s. TB herd incidence in parts of the Southwest of England had remained about three times higher than in the rest of GB, despite the retention of an annual (and occasionally more frequent) tuberculin testing regime in those areas.10
  • 1975-1982 Gassing
    Ministry for Agriculture and Food became responsible for badger culling operations in 1975, which it implemented by gassing badgers in their setts using cyanide gas. Under this policy gassing operations were conducted in a total of 166 areas, averaging 7km2, throughout the South West of England.15
  • 1982-1986 Clean ring
    The 'clean ring strategy' was a badger culling strategy introduced in 1982. It involved cage trapping badgers on land occupied by affected cattle herds, then on adjoining land, expanding outwards until no further infected animals were captured.16 It was abandoned in 1986 because a cost-benefit analysis showed that it could not be economically justified.15
  • 1986-1997 Interim strategy
    The interim strategy was a badger culling strategy where badgers were cage trapped and shot10. Culling was undertaken only where infection could be reasonably attributed to badgers, and was restricted to the land occupied by the breakdown herd.15
  • 1994-1996 Live test
    The live test was a badger culling trial where badgers were cage trapped and shot. Badger groups were randomly allocated to test or interim strategies. Badgers were tested using the BROCK ELISA antibody test.10 The prevalence of TB in badgers culled on the basis of BROCK test positivity was found to be 37.5% and in badgers culled under the interim strategy in the 'no live test' control areas was found to be 34.1%.11
  • 1998-2005 Randomised Badger Culling Trial
    During this trial 10,979 badgers were cage trapped and shot in a population estimated to be between 300,000 and 350,000.20
  • 2005-2012 No badgers were officially culled in Great Britain

New Zealand milestones

  • 1837 Brush-tailed possums were introduced to New Zealand from Australia
    Brush-tailed possums were introduced to New Zealand from Australia in 1837 in an attempt to start a fur trade.12
  • 1970 Department of Agriculture increased the frequency of cattle testing to every three months
    In 1970, the Department of Agriculture increased the frequency of cattle testing to every three months and farmers were forced to comply.13 This was applied to the West Coast region.17 However in 1972, 3,555,000 tests were performed on a cattle population of 8,631,413. (See data supplied by New Zealand in the table above.) This would imply that by 1972 the 3-monthly testing regime had been abandoned.
  • 1972 Intensive possum control programme was started
    The initial control operations focused on Tb possums between 1974 and 1978.18 A graph which shows funding for control operations between 1977 and 2009 shows that funding was relatively low between 1977 and 1994.19
  • 1994-1996 Use of 1080 poison peaked
    Between 1972 and 2000, 1080 poison had been used to reduce possum numbers over 3 periods. These were from 1972 to 1976, 1987 to 1989, and 1993 to 1999. In a report published in 2000, a graph shows that between 1968 and 1999, use of 1080 strongly peaked in the years 1994, 1995 and 1996.14
  • 1994-2009 Vector control funding substantially increased
    Between 1994 and 2003 funding for vector control steadily increased so that in 2003 it was about 7 times more than it was in 1994. In a graph which extends up to 2009, it is shown that funding between 2003 and 2009 then stayed roughly level.19

The New Zealand way

This section gives insight into the approaches used by New Zealand to tackle bovine TB, why these approaches have been so outstandingly successful and the limitations associated with some of these approaches. It also refers to the visit which New Zealand made to the UK and Ireland when offering advice in November 2008. It offers an opinion as to what needs to be in place before England can start to make progress with its eradication programme and may offer an insight into what advice was given in November 2008.

The following is an extract from an email received on 07Apr09 from Dr Paul Livingstone who is the Technical Manager of the Animal Health Board (AHB) in New Zealand. The AHB is an independent non-government organisation that receives 63% of its funds from industry and 37% from Government. New Zealand's annual expenditure for TB control is NZ$83m which is about 33 million pounds sterling. This works out at a cost per cattle herd to be about half of what it is in England.

" New Zealand has made good progress with its TB control programme because we have been able to control our wild-life TB vector - the possum. There are three components to our TB control programme - Test and slaughter (with a high degree of intelligent retesting of test-positive animals based on epidemiological analysis); Movement control (both at a herd and area level) and wild animal control. The latter element has been the critical element that has seen our infected herd numbers reduced by over 90% in the last 12 years (now down to 126 infected cattle and 8 infected deer herds). There have been herds which have been overdue for testing in New Zealand, of which maybe one or two may have been found infected when they were tested. However, as stated before, the main reason for TB in cattle and deer herds in New Zealand is due to Tb possums. In some small localities, Tb ferrets may play a role. TB wild animals are the source of infection for >80% of our infected herds. The balance of infection is largely due to movement of infected animals with a smaller proportion due to residual infection in herds that apparently clear through testing but have an anergic animal left in the herd that at some later date becomes a source of infection to its herd mates.

Over time, TB possums (and other wild animals) have been identified in 25 different geographic areas - that together amount to about 38% of New Zealand's land area. However, possums are a non-native (imported from Australia) conservation pest in New Zealand and thus we are able to kill them. As a result, we have eradicated TB from 10 of the geographic areas through targeted killing of possums. In those areas where TB possums are still present, we undertake control to maintain very low possum densities such that spread of infection from possums to cattle is significantly reduced. This is the reason why the New Zealand programme has been successful. We probably do less herd testing than in the UK, but what is done is targeted at risk areas. Similarly, we have strict cattle and deer movement control for those areas where TB possums pose the greatest risk to herds. These assist in preventing spread of infection through movement of cattle and deer.

With regard to the UK and Irish TB control programme, it is possible that reducing overdue tests may assist in stopping the spread of a small amount of infection, but in my considered view, this would be insignificant alongside your main source of infection for cattle, which is the badger. I understand that you are not able to kill badgers in England, though Wales is attempting to undertake some limited killing of badgers and Ireland has a relatively large badger control programme. I understand that the latter has been very successful where it has been applied.

Given that in the UK you are not able to control badgers, vaccination of badgers against TB appears to be your only option (vaccination of cattle has so far not shown to be efficacious). I note that your government is starting a badger vaccination programme, though catching and parental vaccination of badgers. The AHB and Otago University in New Zealand have developed an oral TB vaccine for possums. This is being managed by a company Immune Solutions Ltd (ISL). The vaccine is stable at room temperatures for about 4 weeks and is fed to possums in baits. In November 2008 we visited UK and Ireland to assess interest from Defra and DAFF regarding use of this vaccine for badgers in the UK and Ireland respectively. The oral vaccine has already being evaluated in Ireland and seems to be relatively efficacious in preventing TB in badgers. Further research is currently being undertaken in Ireland. Provided Ireland and the UK are prepared to undertake badger research to determine efficacy of the oral vaccine in infected badger populations sufficient to support registration of the vaccine in badgers in the UK and Ireland, and are prepared to then purchase and use the vaccine correctly, ISL will look to register the oral vaccine for use in badgers. As I understand, it will take about 3 - 4 years to gain sufficient information to register the vaccine for use in badgers in the UK and Ireland. However, to eradicate TB from badger populations through vaccination will mean annual vaccination of badger populations for some 4 - 5 badger generations or around 20 years - which is some commitment.

The other main difference between the New Zealand and the UK programme is that in New Zealand, farmers fund and are deeply involved in all aspects of the TB programme. Representatives of dairy, beef and deer industries together with regional and central government elect the Directors to the AHB Board. All 6 Directors of the AHB are either farmers or have farming connections. In comparison, from my understanding of the UK situation, UK farmers don't appear to want to be involved - especially don't want to pay. Once farmers accept that they should pay, then they can start having a say in the form of the programme. From the New Zealand experience, it wasn't until farmers started paying and taking responsibility for the programme that it started making progress.

A rather long email, which I hope conveys from some 35 years of involvement with New Zealand's TB control programme, that overdue testing is not likely to be the panacea that you were hoping for. I suggest that you should direct your attention to using all means at your disposal to keep badgers separate from your cattle until such time as you know though vaccination or other means, that they no longer pose a risk to your herd.
"

References

  1. Request for information: Overdue bovine tb tests. This request prompted the off-topic response given above.
  2. World bovine tuberculosis experts gather in Wellington, New Zealand in August 2009 for the 5th International Bovine Tuberculosis Conference.
  3. Tackling bTB the New Zealand way. An update from NFU Head of Food and Farming, Kevin Pearce, at the 5th international conference on bovine TB.
  4. Tb-infected herds first-time fall below 100
  5. New Zealand's top TB experts back from Wales
  6. Dr Paul Livingstone is awarded the Queen's Service Order for services to veterinary science
  7. Dr Paul Livingstone receives QSO from Governor-General
  8. Dr Paul Livingstone of the Animal Health Board awarded the Queen's Service Order
  9. Number of TB-infected herds in New Zealand in November 2011 was at an all-time low
  10. History of TB control in the UK
  11. Krebs, J.R., Anderson, R.M., Clutton-Brock, T., Morrison, W.I., Young, D. and Donnelly,C.A., Bovine tuberculosis in cattle and badgers, MAFF Publications, PB3423, London.(1997)
  12. The reassessment of 108O
  13. A message from the chief executive of TBfree New Zealand
  14. Possum control
  15. Final Report of the Independent Scientific Group on Cattle TB
  16. The effects of annual widespread badger culls on cattle tuberculosis following the cessation of culling - Supplementary Information
  17. The development of long term management plans for bovine TB possum control
  18. The use of 1080 for pest control
  19. Is the New Zealand TB control programme making an impact
  20. Great Britain and Republic of Ireland badger culling trials: An initial comparative study. Published in 2009 by C.M O'Connor et al at Glasgow University
  21. Number of cattle in England, Wales, Scotland, Northern Ireland, Great Britain and the UK for each year from 1866 to 2010
  22. Making TB History - Chapter 4: Why is possum control the key to beating bovine TB in New Zealand?
If you would like to send to me your comments, please contact me.
Last Modified 10 Apr 2014 22:11
Cookies policy
Most recent
additions and updates
PDF icon Laboratory study of Mycobacterium bovis infection in badgers and calves. TW Little et al. Vet Rec. 1982 Dec 11;111(24):550-7.
Added or updated 18 minutes ago
 A critique of the Randomised Badger Culling Trial (RBCT)
Added or updated 53 minutes ago
 Objective
Added or updated 5 days ago
 Bovine TB in different regions of GB since 2008
Added or updated 7 days ago
 Accuracy of the TB test for cattle
Added or updated one week ago
PDF icon Tuberculin manufacturing source and breakdown incidence rate of bovine tuberculosis in British cattle, 2005-2009. S. H. Downs et al. Journal of the British Veterinary Association. Accepted 10 Oct 2012. Published Online 16 Nov 2012.
Added or updated one week ago
 Prevalence of bovine TB in Wales, England, Scotland and Ireland
Added or updated one week ago
 Bovine TB in Ireland
Added or updated one week ago
 Bovine TB in the UK, England, Ireland, Wales and New Zealand
Added or updated 2 weeks ago
 TB test interval maps
Added or updated 2 weeks ago
 Bovine TB in New Zealand
Added or updated 2 weeks ago
PDF icon Andrew George MP promoting badger vaccination at the green fair. Thursday 1Oth April 2014 in News. www.smallholder.co.uk
Added or updated 2 weeks ago
PDF icon A model for assessing the relative humaneness of pest animal control methods. Second edition June 2011 by Trudy Sharp and Glen Saunders. Vertebrate Pest Research Unit. Commonwealth of Australia.
Added or updated 2 weeks ago
 Targeted gassing of badgers and associated challenges
Added or updated 2 weeks ago
PDF icon Tuberculin Test Report and Certificate of Clinical Inspection for Veterinary Inspectors. TB52/VI (09/08). DEFRA, Scottish Executive, Welsh Assembly Government.
Added or updated 3 weeks ago
PDF icon Pilot Badger Culls in Somerset and Gloucestershire. Report by the Independent Expert Panel. Chair: Professor Ranald Munro. Presented to DEFRA Secretary of State Owen Paterson MP, March 2014.
Added or updated 3 weeks ago
PDF icon The Strategy for achieving Officially Bovine Tuberculosis Free status for England. April 2014. www.defra.gov.uk
Added or updated 3 weeks ago
PDF icon Bovine tuberculosis: Infection status in cattle in GB. Extract of the executive summary and figures from the annual surveillance report. For the period January to December 2010. Commissioned by DEFRA, Scottish Government, and Welsh Government under Project SB4500. Project Leader: Mr P A Upton.
Added or updated one month ago
PDF icon Bovine tuberculosis: Infection status in cattle in GB. Extract of the executive summary and figures from the annual surveillance report. For the period January to December 2011. Commissioned by DEFRA, Scottish Government, and Welsh Government under Project SB4500. Project Leader: Mr P A Upton.
Added or updated one month ago
PDF icon Bovine TB - The Facts. Bovine TB Advisory Group. DEFRA. April 2009.
Added or updated one month ago