Salmonella is a bacterium of which more than 2400 different types (called serotypes) have been identified. The bacterium can be found in the gastrointestinal tract of wild and domestic animals, birds (especially poultry), reptiles, amphibians (for example, terrapins), and occasionally humans.
Infection with salmonella can cause watery and sometimes bloody diarrhoea, abdominal pain, headache, nausea, vomiting, and fever. Salmonella is one of a number of organisms that gives rise to illness collectively known as 'food poisoning'
Who gets it and how serious is it?
Anyone can become infected with salmonella. Infection is frequently associated with eating foodstuffs (most commonly red and white meats, raw eggs, milk, and dairy products) containing the bacterium, most usually following contamination of cooked food by raw food or by failing to achieve adequate cooking temperatures.
Person to person spread, usually during the acute diarrhoeal phase of the illness, and contact with infected animals can also cause infection.
The illness can range from mild to severe. The elderly, infants, and those with impaired immune systems are more likely to have a severe illness. In some cases, the salmonella infection may spread from the intestines to the blood stream, and then to other body sites and can be fatal without treatment. More information on salmonella is available from the World Health Organisation (WHO) website.
The majority of patients with infections caused by salmonella do not require specific treatment and make a full recovery although the advice of a health professional should be sought in all cases of severe diarrhoea and hospital treatment may be necessary.
If infection spreads from the intestines to the blood stream, prompt hospital treatment with certain antibiotics is required.
How common is it?
Many cases of salmonella appear sporadic but outbreaks occur in the general population and in institutions.
Rates of salmonella in Wales and the UK have fallen dramatically in recent years from a peak of infection recorded in 1997.
This falling trend may be attributable to many reasons including greater public awareness about food safety but the most important factor is the compulsory vaccination of the UK egg-laying flock, introduced in 1998, against Salmonella Enteriditis.
In Wales during 2011, the reported rate of salmonella infection in the general population was 15 cases per 100,000 people. This compares to a rate of 80 cases per 100,000 in 1997. More information about the monitoring of salmonella is available from the Public Health Wales Health Protection microsite from the link: rates and surveillance of salmonella in Wales
As many people with salmonella do not seek medical treatment for their illness, the number of reported cases of Salmonella will be less than the actual number of cases occurring. However, data collected provides important information on the general trend on the rate of Salmonella infection in Wales.
Many cases of salmonella can be prevented by the correct storage and cooking of foods and employing hygienic food handling and preparation procedures. Avoidance of certain foods, for example milk and dairy products that are unpasteurised and raw eggs can also lower the risk of illness.
Advice on the safe preparation, storage, cooking and handling of food is available from the Food Standards Agency website.
Washing hands thoroughly before eating or preparing food, after using the toilet, changing nappies or cleaning up after others with diarrhoea and after contact with domestic or farm animals can also prevent infection.
Minimising impact in Wales
Surveillance of salmonella is undertaken in Wales by Public Health Wales to provide timely reporting of sporadic cases, detection and containment of outbreaks and to identify any trends in the rates of infection over time.