All posts by lisa lee

Species at Risk

A variety of mammalian species are susceptible among livestock, wild, and domestic animals (O’Reilly and Daborn, 1995).

Badger and cow, two main hosts of bTB

Susceptible species, in addition to humans, include:

Livestock:

  • Cattle (main host)
  • Goats
  • Pigs
  • Sheep

Wildlife:

  • Badgers
  • Deer

Domestic animals:

  • Cats
  • Dogs

Bovine Tuberculosis

(WARNING: This post contains a graphic image!)

What is bovine tuberculosis (bTB)?

  • Highly infectious, chronic respiratory disease
  • Caused by the bacteria, Mycobacterium bovis
  • Results in granulomatous lesions in respiratory tract and infected organs, and potentially death
  • Affects livestock, wildlife, and domestic animals, as well as humans
  • Has potential to greatly damage livestock industries as infected cattle must be culled to prevent widespread outbreak
Deer infected with bTB, with numerous lesions on the lungs and ribs.

History of bTB in Great Britain

Pre 1960s – Height of infection:

  • Up to 40% bTB infected cattle in 1930s (Reynolds, 2006)
  • Lack of milk pasteurization = 40,000 human infections annually
  • Implementation of movement restrictions and voluntary cattle testing in 1947

1960s – Reduced levels due to cattle testing:

  • Compulsory cattle testing further drops bTB levels significantly

1970s – First badger culls:

  • Badgers discovered to be infected with bTB in 1971
  • Trial badger culls begun in 1975 through hydrogen cyanide gassing of setts (Lodge and Matus, 2014)
  • Hydrogen cyanide gassing eventually considered inhumane -> switch to live cage trapping and shooting

1990s – Increasing bTB infections & Krebs Report:

  • Rapid increase in new cases, correlated with Foot and Mouth Disease outbreak as replacement herds may have been infected with bTB
  • Krebs Report (1997) find link between badger and cattle infection, but actual risk not quantified
  • Development of government Five Point Plan to control bTB

1997 to 2008 – Randomized Badger Culling Trials (RBCT):

  • Found culling ineffective over long term, unless occurs over large areas of land
  • Due to findings, government does not proceed with culling policy in 2008

2010 – A new government, a new policy:

  • Farmers allowed to cull badgers for min. 4 years (controversial decision)
  • Culling delayed until 2013 due to unknown badger populations and lack of police to regulate culling

2013 to present – Free shooting culls:

  • Trial culling by free shooting
  • Minimum cull numbers not reached in pilot areas in Somerset and Gloucestshire
  • No evidence of effectiveness but culls to be continued anyway…

Timeline of Events

Bovine tuberculosis has ranged in degree of impact to Great Britain over the past century, from the height of cattle infection in the 1930s to diminishing levels in the 1960s. However, with the outbreak of other livestock diseases such as Foot and Mouth Disease, a rapid increase in bTB has appeared in Britain. This section aims to highlight the major events occurring regarding bTB in Great Britain.

no_of_cattle_reacting_to_TB_skin_test

Alternatives to Free Shooting Cull

no hunting no shooting

Free shooting badger culls, currently used in Britain, is not considered by many scientists and animal rights activists to be the most humane or effective method of controlling bovine tuberculosis. There exists a number of different ways that this disease can potentially be controlled, and may be used in combination with badger culling for increased efficiency:

  • Vaccinations
  • Livestock Management & Surveillance
  • Fertility Control

In addition, alternatives to a free shooting method for culls may involve:

  • Gassing Setts (underground badger dens)
  • Cage Trapping