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Tuberculosis affects mammals, including people, and birds. The causal organism, Mycobacterium tuberculosis, is sub-classified into types, human, bovine and avian. The avian type is referred to as M. avium or more often the avian/intracellulare complex because it is not a uniform species. M. avium itself infects mainly birds but is also found in the environment along with M. intracellulare which is predominantly saprophytic or free living. Pigs are rarely infected by the human or bovine types but are commonly infected by the avian/intracellulare complex.

The avian/intracellulare complex also causes sub-clinical non-progressive infection in healthy people. The main concern is that it could cause more serious disease in immuno-suppressed people and people with AIDS.

In most countries if lesions are found in the neck at slaughter the whole head is condemned and if they are found in the mesenteric lymph nodes which drain the intestines the offals are condemned. If they are more widespread in the body, which is rare, the whole carcass may be condemned or cooked. If small lesions are missed by the meat inspector normal kitchen cooking destroys the organism.


All Pigs
  • It causes small nodules in the lymph nodes of the neck and those that drain the small intestine.
  • In the great majority of cases the lesions are non-progressive, they do not spread through the body, do not make the pig ill and are not excreted.
  • There are no clinical symptoms and there is no difference in performance between infected and non-infected pigs.

Causes / Contributing factors

  • The disease does not spread between pigs and should be regarded as an environmental infection. It is rarely diagnosed in living pigs.
  • Paddocks that have been treated with poultry manure up to one year previously, (or, in the case of bovine TB, which have been grazed by infected cattle or badgers).
  • Avian TB as the name implies is found in wild birds. The organism is shed in large numbers via droppings and therefore food, grain or bedding contaminated by birds becomes a potent source.
  • Peat often contains M. intracellulare. Peat is used both for bedding and gut stimulation in the young piglets. It should only be used if it as been pasteurised.
  • Water contaminated by M. avium/intracellulare is often a source.


In living pigs diagnosis is by the skin tuberculin test but usually it is brought to the farmer's attention by high condemnation rates at slaughter.

Further Reading

Click on the links below to find out more about this disease, including treatment, management control and prevention information. The top link is the main article on this disease.