Atlas of foodborne infections
transmitted by contaminated food and water

Atlas of Patogens Contents Information sources Glossary Administration

Salmonella

CZ: salmonela
EN: salmonella

Occurrence:
Meat and Meat Products
Milk and Milk Products
Fruits and Vegetables
Eggs


Category:
Bacteria


Foodborne Disease:
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salmonellosis - diarrhoea, fever, and abdominal cramps


Description:
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Salmonella spp.
are microscopic bacteria living in the intestinal tracts of humans and other animals, including birds and pass from the faeces of people or animals, to other people or other animals. This infection is called salmonellosis. Serotypes Salmonella typhimurium and Salmonella enteritidis are the most common.

Salmonella are usually transmitted to humans by eating foods contaminated with animal faeces. Contaminated foods usually look and smell normal. Many raw foods of animal origin, such as beef, poultry, milk, or eggs, but all foods, including vegetables may become contaminated. Thorough cooking kills Salmonella!

Most persons 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 persons recover without treatment, but diarrhoea may be so severe that the patient needs to be hospitalized and require rehydration.
Determining that Salmonella is the cause of the illness depends on laboratory tests of samples of stools. Salmonella bacteria have become resistant to antibiotics, largely as a result of the use of antibiotics to promote the growth of feed animals.

A small number of persons who are infected with Salmonella, will go on to develop pains in their joints, irritation of the eyes, and painful urination. This is called Reiter’s syndrome. It can last for months or years, and can lead to chronic arthritis, which is difficult to treat.

Salmonella species can be split into more than 2000 serotypes according to the Kauffman-White surface antigens scheme. A small number of serotypes accounts for most of the infections, with S. typhimurium and S. enteritidis predominating. Salmonella typhi and S. paratyphi are responsible for the so-called enteric fevers (typhoid and paratyphoid, respectively), which are primarily water-borne. Salmonella is the second most commonly reported bacterial cause of gastroenteritis after Campylobacter.

Undercooked (or improperly heat treated) food from infected food animals is most commonly implicated. Egg-associated salmonellosis is an important public health problem in the USA and Europe. It is caused by S. enteritidis that infects the ovaries of apparently healthy hens, which then lay contaminated eggs. If the eggs are eaten raw or undercooked, salmonellosis may result.


Pictures:

Salmonella
Source: Detail of Salmonella colonies on the agar
Salmonella
Source: A magnified view of salmonella bacteria - scan microscopy
Salmonella
Source: A magnified view of salmonella bacteria (colored)
Salmonella
Source: A salmonella under the light microscope (colored)
Salmonella
Source: Eggs - source of bacterial infection
Salmonella
Source: Modes of Salmonella transmission
Salmonella
Source: Poultry meat - source of bacterial infection
Salmonella
Source: Salmonellosis: food-borne disease campaign

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