Badgers were first discovered to carry bovine tuberculosis (bTB) in 1971. Since then much research has been undertaken and badgers are now widely considered to represent a significant wildlife ‘reservoir’ of this disease.
Cattle are by far the most susceptible domestic species to the M.bovis bacteria, although farmed deer, boar, bison, buffalo, goats, llamas and alpacas can also be affected.
How does TB spread?
In hotspot areas of cattle TB, the badger population is considered to play a significant role in maintaining the disease and in preventing its eradication. Although other wild mammals carry the disease, badgers have high rates of infection (the number of animals contracting the disease) and high rates of being infectious (where an infected animal then starts spreading the disease).
The ecology and behaviour of badgers means the potential transmission to cattle is high. For example, badgers often forage in pasture, and can spread the disease by cattle sniffing infected faeces and urine. It is considered that these factors make badgers an important link in the cycle of disease. Other routes of disease transmission include direct contact between badgers and cattle and transmission within farm buildings where cattle are housed or feed is stored.
Once a bovine (e.g. a cow) is infected, however, it does not immediately start spreading the disease. TB develops very slowly and it takes time for lesions to grow in the lungs, and these lesions have to open up before cattle start coughing out the bacteria.
What are the symptoms of TB?
TB is primarily a disease of the respiratory system but very few cases are reported in cattle. This is possibly because the symptoms are very similar to other respiratory diseases but also because regular TB testing of dairy herds catches the infection long before it becomes a chronic disease visually affecting the animal.
As lesions are most common in the lungs (called tubercules) a hard, dry, short cough is usually the first symptom, leading to more frequent coughing and laboured breathing. As this continues cattle will lose condition and later cough up blood.
What is the scale of the TB issue in humans?
The Department of Health still views TB as a ‘major public health problem’ and of the 9.2 million new worldwide cases of TB in 2007 (resulting in 1.7 million deaths!) around 7,750 were in the UK.
In the UK and across the world, more than 99 per cent of new cases in humans are caused by M.tuberculosis and not M.bovis. The risk is still there and so TB is a notifiable disease in all farmed animals. TB in humans presents with the same symptoms whether it is caused by M.tuberculosis and not M.bovis.
How do farmers prevent their cattle being infected by TB?
Farmers are required to undertake regular dairy herd surveillance testing for the disease. If cattle test positive they are sent for compulsory slaughter. In 2010 around 25,000 cattle were slaughtered costing the taxpayer tens of millions of pounds. Once a farm has had TB detected in its herd, movement restrictions are placed on that farm. This means animals cannot be moved off the farm (unless straight to slaughter) until the herd passes two further tests, to ensure TB is no longer detected in the herd.
Farmers can often be surprised at the level of badger activity in and around farm buildings, so they also take practical measures to prevent their animals contracting the disease from badgers. Husbandry measures, such as ensuring gates on cattle sheds and feed stores fit well and are shut at night and raising troughs and salt licks.
The financial implication to farmers.
Regular testing and slaughter of animals is a stressful and costly affair. Although farmers receive money for the animals slaughtered, the amount received does not always accurately reflect the true cost of that animal, for example when high value breeding stock contract the disease.
Government figures state that every time a farmer has a breakdown in the herd it will cost an average of £33,000, although this figure can vary greatly between farms. The compensation paid does not cover any consequential losses, for example the loss in milk sales, or the cost of hiring more labour to help with TB testing.
Is culling badgers the right answer?
A poll conducted by the BBC last year found that about two-thirds of the public oppose culling, with majorities in every age group, region and across both genders.
I’m sure the general perception of badgers is a classically beautiful English animal, but before the question of, ‘do you oppose killing badgers to curb cattle tuberculosis’ with a simple yes or no answer, might it be better to enlightened the general public that it’s ultimately costing the taxpayer about £100m per year and resulting in the death of tens of thousands of cattle?
Your views & thoughts?