Can hunting spread bovine TB?

Can hunting spread bovine TB? This is an interesting question which has never been researched. For those who experience the hunt on their land, very few are likely to consider the biosecurity risks from so many dogs, horses, people and vehicles as they pass unhindered from one farm to another. Interestingly hunts were suspended for around 10 months during the Foot and Mouth outbreak in 2000-2001. In the battle against bovine TB there has been much emphasis on the importance of bio-security, so surely any potential source of bacteria spread should not be ignored if the risks of bovine TB are to be believed? However, saying that we know that some basic areas of concern, eg spreading slurry on land, whilst being recognised as potential sources of infection, have been largely ignored, with such practices continuing, presumably because this is a difficult area to control. This is extracted from an NFU advice sheet; “Bovine TB organisms can be excreted in the faeces of infected cattle – potentially contaminating the farm environment. Storing slurry or manure helps kill off the TB bacteria over time. You can use slurry or manure on your own land while TB restrictions are in place, although you should consider the risk of spreading the disease to other stock or wildlife.”

It was VIVA, the Vegetarians' International Voice for Animals, that posed the question recently about the potential role hunts play in spreading TB in cattle (and wildlife). Could hunting with hounds carry some of the blame? This group raised the issue with James Paice, Minister for Environment, Food & Rural Affairs. The group included a map highlighting the areas of bovine TB and hunting. Viva suggested there is a correlation between areas where hunting takes place and TB; "The South and Southwest of England and Wales appears to have a higher concentration of hunting than anywhere else in the country – and it is here where TB infection is at its highest Of course there is hunting in other parts of the country, but our suggestion is not that hunting is a lone vector but is a possible accelerant to existing disease spread." A hunt will typically be made up of 20 horses, 20-40 dogs and quad bikes which race across the fields of about five farms on each outing and often operate over such wide areas that it can include two counties or more. They go out up to three times a week and vary their courses.

The NFU offers this advice: “Cleansing and disinfection is an important disease control measure and may help reduce the risk of infection spreading to other cattle or to other susceptible animals on your farm. Under certain conditions, M. bovis can survive in the environment for a long time, so it is good practice, and will be a requirement under notice, served by Animal Health, to cleanse and disinfect thoroughly all buildings where reactor cattle have been kept.  It is particularly important to clean and disinfect any fittings or equipment that may have come into contact with sputum, faeces or milk from TB reactors.” The NFU also says: that whilst TB bacteria may only be infectious on pasture for a few days (but potentially more depending on the weather) it can remain infectious in cattle faeces for up to 8 weeks. It can remain infectious in soil for over 12 weeks. Viva says 'What better clod-flying rotavator (outside farm machinery) could there be than 20 galloping horses and many dogs? Is it really such a stretch to imagine that this could be a route for passing TB to presently uninfected herds (and potentially to uninfected wildlife)?'

In a letter dated 5 May 2011 from Professor Christianne Glossop, she says; 'I do not deny that hunts could potentially increase the risk of spread of TB, however, there is no evidence of this. It would not, therefore, be proportionate to prevent hunts accessing the countryside, nor is it within my power to do so.' She goes on to say; '... biosecirity is about putting in place measures to mitigate the risks of disease spread. I am clear that farmers should put in place appropriate measures to reduce disease transmission that are practical and proportionate. I also expect those who utilise the land for recreational purposes to be respectful and mindful of the potential for disease spread'. One does wonders just how proportionate it is to kill healthy cattle and badgers under the existing archaic policy that clearly is not working and is worse than the disease itself?

Defra letter
Thank you for your email of 13 February to Jim Paice about bovine TB.

You asked whether hunting has been considered as a vector for the spread of TB. There is no evidence that hunting contributes to the spread of TB. In addition, we are not aware of any evidence to indicate that hunting or any other countryside activity or recreation may be a significant factor. There is no obvious correlation on your map between the locations of hunts and high incidence of TB in cattle. The map clearly shows that hunting also takes place in areas of low TB incidence.

The M. bovis bacterium is not like the highly contagious viruses such as Foot and Mouth disease where we are concerned about spread by fomites (objects or vehicles that are capable of transmitting infectious organisms from one individual to another). This is because of differences in how well the pathogen survives in the environment and how it spreads between animals. 

You suggest that there is no evidence that hunting contributes to the spread of bovine TB because we have not looked for it. Our bovine TB Research & Development Programme is overseen by an independent TB Science Advisory Body, which provides expert oversight of Defra-funded bovine TB research, identifies gaps in the current evidence base and provides independent advice on the strategic direction of, and priorities for, all Defra-funded TB-related research.

New research ideas can be submitted by researchers as a concept note that should provide details of: any preliminary evidence to support the hypothesis put forward (including references to any relevant published scientific papers); how it is proposed to test the hypothesis including statistical justification for the proposed sample size; who would carry out this research and their expertise in this type of study; and the proposed length of time and cost of this research.

Further details and the CSG16 form are available for download via:
http://www.defra.gov.uk/corporate/evidence/science/research-funding/research-forms/
VIVA www.viva.org.uk/campaigns/badgers/hunting.php