Of the many serotypes of salmonella that exist, the ones that are most likely to cause clinical disease in pigs are Salmonella choleraesuis , and Salmonella typhimurium and to a lesser extent Salmonella derby . Many such carriers do not shed the bacteria in faeces unless they are stressed. Pigs may be intermittent or continuous faecal shedders of other serotypes but the carrier state is usually short, weeks or a few months and is self limiting. S. typhimurium and S. derby are more likely to cause milder disease, the main sign of which is usually diarrhoea. The serotype most commonly found in pigs, however, is Salmonella typhimurium which sometimes is associated with diarrhoea in young pigs but which is also a major cause of food poisoning in people.
Some strains have multiple medicine resistance.
If it is diagnosed in your pigs you should take hygienic precautions not to become infected yourself. Many other so called exotic types may also be detected in pigs without causing disease. Remember that S. typhimurium , which occasionally can be isolated from pigs, are common causes of food poisoning in people. Salmonellosis can occur at any age but is most common in growing pigs over eight weeks of age. Severe S. choleraesuis infection occurs typically at around 12 to 14 weeks.