Salmonellosis

What is salmonellosis?
Salmonellosis is a very common infection of the gastrointestinal tract caused by a bacterium called Salmonella. This group of bacteria can pass from the faeces of people or animals, to other people or other animals. There are many different kinds of Salmonella bacteria. Salmonella serotype Enteritidis and Salmonella serotype Typhimurium are the most common in Ireland.

What are the symptoms of infection?
People infected with Salmonella develop diarrhoea, fever, and abdominal cramps 12 to 72 hours after infection. The illness usually lasts 4 to 7 days, and most people recover without treatment. However, diarrhoea can occasionally be severe enough to warrant hospital admission. The elderly, infants, and those with impaired immune systems are more likely to have a severe illness.

How is it diagnosed?
A simple laboratory test on a sample of stool (bowel motion) can usually confirm the diagnosis. Your doctor may order this test if he/she suspects salmonella. It is important to diagnose it because of the likelihood of spread. People who prepare food, the elderly, and children who are not properly toilet trained are at greater risk of spreading salmonella. In the case of such people, your doctor may decide to send off a sample of stool to the lab for testing. 

How is it treated?
Salmonella infections usually resolve in 4 to 7 days and often do not require treatment unless the patient becomes severely dehydrated or the infection spreads from the intestines. Persons with severe diarrhoea may require rehydration, often with intravenous fluids. Antibiotics are rarely necessary and are reserved for use in the very ill. 

Are there long term consequences to a Salmonella infection?
Patients usually recover completely, although occasionally they may have some upset in their bowel habit for a number of months. A very small number of individuals who are infected with Salmonella, will go on to develop joint pains, irritation of the eyes, and painful urination. This is called Reiter's syndrome. 

How do you catch Salmonella?
Salmonella live naturally in the intestinal tracts of humans and other animals, especially birds. Salmonella are usually passed to humans by eating foods contaminated with animal faeces. It is rarely possible to tell if food has been contaminated as it usually looks and smells normal. Contaminated foods are often of animal origin, such as, poultry, milk, eggs or beef, but all foods, including vegetables may become contaminated. Thorough cooking kills Salmonella. Food may also become contaminated by the unwashed hands of an infected food handler, who forgot to wash his or her hands with soap after using the bathroom.

Salmonella may also be found in the faeces of some pets, especially those with diarrhoea. Reptiles such as tortoises and lizards are particularly likely to carry Salmonella and hands should always be thoroughly washed immediately after handling a reptile, even if the reptile is healthy. Adults should also be careful that children wash their hands after handling a reptile.

What can I do to prevent salmonellosis?

• Cook poultry, minced beef, and eggs thoroughly before eating. Do not eat or drink foods containing raw eggs, or raw unpasteurised milk. 
• Wash hands, kitchen work surfaces, and utensils with soap and water immediately after they have been in contact with raw meat or poultry.
• Wash your hands before eating or preparing food and after using the toilet. 
• If you are served undercooked meat, poultry or eggs in a restaurant, don't hesitate to send it back to the kitchen for further cooking. 
• Be particularly careful with foods prepared for infants, the elderly, and the immunocompromised. 
• Wash hands with soap after handling reptiles or birds, or after contact with pet faeces. 
• Avoid direct or even indirect contact between reptiles and infants or immunocompromised persons. 

What is the situation in Ireland?
The number of human cases of salmonellosis has decreased since the year 2000. For the past number of years all poultry farms in the Republic of Ireland have been tested and monitored for Salmonella and any flocks found to be harbouring with a common Salmonella, S. Enteritidis are slaughtered. However, not all eggs on the market originate in the Republic of Ireland. Over the last number of years, an increasing percentage of those with Salmonella have become infected outside Ireland, holiday destinations in particular leading to a significant number of infections.

The Food Safety Authority have an excellent resource on salmonella.

Content based on the CDC factsheet.

Last reviewed: 2nd July 2010