Salmonellosis

Salmonellosis is a gastrointestinal disease caused by bacteria of the genus Salmonella. The bacteria multiply in unrefrigerated foods and are then usually ingested when these foods are eaten. 

In Germany, this foodborne infection occurs primarily after consuming dishes containing raw eggs or raw meat that have not been heated sufficiently. This typically causes diarrhea. Antibiotics should only be used for certain risk groups when treating salmonellosis.

Salmonellosis causes acute intestinal inflammation. This typically results in sudden-onset diarrhea. There may also be a mild fever, headache and abdominal pain, discomfort and, sometimes, vomiting. The symptoms can last for several days and then subside on their own.

If severe diarrhea persists for a long time, there may be a significant loss of fluid (dehydration), in which important salts are also lost. This further impacts a person’s general condition. In infants, young children, and the elderly, severe fluid and salt loss can cause significant strain on the person’s circulation and become life-threatening. 

In rare cases, the inflammation spreads from the intestine to other organs and leads to high fever (septic course).

A salmonella infection is caused by bacteria of the genus Salmonella. Salmonellosis is one of the classic foodborne infections. It is different from typhoid and paratyphoid that are caused by other types of Salmonella bacteria and are usually accompanied by fever and severe illness. Both of these illnesses are rare in Germany and are usually brought into the country by travelers.

In most cases, the salmonellosis pathogens enter the body through infected food. However, they can also be spread from person to person or from animal to human.

Infection through food containing eggs

In Germany, the Salmonella enteritidis bacteria is widespread. It is transmitted primarily through raw or insufficiently heated eggs, or food containing eggs.

Infection through meat

Another type of Salmonella bacteria, Salmonella typhimurium, is also widely found throughout Germany. It is primarily transmitted through raw meat or meat products that have not been heated or have not been heated sufficiently, such as minced meat or “Mettwurst” meat paste.

Infection from person to person

Infection from person to person can occur through a smear infection, especially if hygiene is inadequate. Infection can also occur via contaminated surfaces.

Infection from animal to human

Infections through direct contact with domestic animals are rare. Reptile owners are most likely to become infected via the animals’ feces. Surfaces contaminated with feces can also be a source of infection.

Other, rarer sources of infection in Germany

Plant foods can also contain Salmonella. For example, herbal tea, mung bean sprouts, and melons have been previously identified as sources of infection. Chocolate and smoked eel are other rare sources of infection in Germany.

In most people, symptoms last a few days. For certain risk groups, however, salmonellosis can sometimes be dangerous, for example, if it leads to severe fluid and salt loss or if the bacteria spread into the body beyond the intestine. This can lead to longer and more severe courses of the disease.

The following groups are at an increased risk of a severe infection: 

• infants
• elderly people
• people with pre-existing conditions 

It is also possible that taking antacid medications increases the risk of contracting the disease. However, the data on this is not clear.

Salmonella infections are common worldwide. Illnesses occur as sporadic cases, clusters of cases, such as in families, or as larger outbreaks. In 2019, there were 277 outbreaks in Germany with more than 1,000 people affected. Due to the measures taken to prevent the spread of COVID-19 between 2020 and 2022, the figures from those years are of limited value.

Mandatory vaccination was introduced in Germany in 2008 for laying hens, broilers, and turkeys. Since then, the number of human infections with Salmonella enteritidis has significantly declined.

There were 13,173 reported cases of salmonella poisoning in Germany in 2023. This figure is similar to those recorded in the years before the COVID pandemic. Every year, around one third of cases are acquired in countries visited for a vacation. Many infections occur in late summer. Children under 5 years of age are most frequently affected. Deaths are rare in Germany. 

After a person becomes infected, symptoms usually appear within 12 to 36 hours (known as the incubation period). Typically, the disease progresses without complications.  

Mild cases

Salmonellosis begins as an acute intestinal inflammation with the symptoms of a gastrointestinal infection. The symptoms subside on their own within 4 to 10 days.

Severe case 

In rare cases, intestinal inflammation can spread to other organs. 

Possible complications are:

• inflammation of the joints
• gall bladder inflammation
• inflammation of the innermost layer of the heart (endocardium) and heart valves
• meningitis
• pericarditis
• pneumonia
• skin disorders
• inflammation of the renal pelvis and kidneys

If severe, salmonellosis should be treated with antibacterial drugs (antibiotics). Treatment in hospital is sometimes necessary.

Fewer than one in 1,000 people die from salmonellosis. Those most at risk are the elderly and people with weakened immune systems.

Salmonella multiplies in a temperature range between 10 and 47 degrees Celsius, and in some cases as low as 6 to 8 degrees. It can survive for several months in its surroundings and in various foods.

Food handling 

The following measures will reduce the risk of Salmonella infection:

• Salmonella can be reliably killed at temperatures above 70 degrees Celsius with a minimum cooking time of 10 minutes.
• Raw meat and sausage products, poultry, seafood, eggs, creams, salads, and mayonnaises with raw egg should be stored in the refrigerator. Ice-cream should be put in the freezer immediately after purchase.
• The cooling time must be kept short for precooked foods. Hot foods should be consumed within 2 hours of the last time they were heated.
• When thawing frozen poultry and game, the water produced often contains Salmonella. It should therefore be collected separately and disposed of immediately. All items that came into contact with it should be thoroughly cleaned with hot water immediately afterwards.
• When meals are heated up in the microwave, a sufficient cooking time is essential to ensuring that the food is fully heated. 
• Baby food should be prepared with water with a temperature of at least 70 degrees Celsius, then allowed to cool quickly and consumed within 2 hours.

The Bundesinstitut für Risikobewertung (Federal Institute for Risk Assessment) has compiled further information on protection against foodborne infections in private households.

Hygiene when cooking

• Wash hands thoroughly with soap after contact with food potentially containing Salmonella.
• Meat should always be prepared on a separate surface, away from vegetables and salad.
• Change kitchen towels frequently and wash them at a minimum temperature of 60 degrees Celsius.

Prevention in kindergartens, schools, and homes

The most important precaution is hand washing. This is especially true after using the toilet, after contact with suspected infectious items such as diapers. Handwashing is also always essential before preparing meals and following contact with foods such as poultry. 

Avoiding infection by affected persons

• Sick persons with symptoms are usually not able to work and should stay home.
• Sick children under 6 years of age should not visit community facilities such as daycare centers and schools. Once recovered, they must be symptom-free for 2 days before returning. Parents must inform community facilities of their child’s illness. 
• Special rules apply to certain food establishments or community food service facilities. Persons suspected of having salmonellosis, who are ill, or who are excreting (“shedding”) Salmonella are temporarily prohibited from working in these locations.

Further information on what to do in the event of a salmonella infection is provided in various languages by the Bundeszentrale für gesundheitliche Aufklärung (Federal Center for Health Education) on its website infektionsschutz.de.

It is not usually necessary to determine the cause of a gastrointestinal infection. Detection of the precise pathogen responsible is only required in certain cases. Diagnostic identification of pathogens is required, for example, in severe cases, in people with certain pre-existing illnesses or those who work with food. It is also useful to detect the pathogen if several people become ill and an outbreak is suspected.

If salmonellosis is suspected, the following specimens may be tested:

• stool
• vomit
• suspicious food
• blood (in severe cases)

All detected cases of salmonella infection must be reported to the local health authority.

Treatment of salmonellosis depends on the progression and severity of the infection.

Treatment of a mild infection

Salmonellosis usually clears up without treatment provided that it is confined to the gastrointestinal tract. However, it is important to compensate for the loss of fluids and salt that it causes. For this reason, it’s important to drink plenty of fluids. Electrolyte solutions, available from pharmacies, can also be beneficial. Antibiotics are not used to treat the infection because they are not required by this patient group and may prolong bacterial excretion so that people remain contagious for longer periods.

Treatment of a severe infection

In severe cases, for example those accompanied by a very high temperature, treatment with antibacterial medication (i.e., antibiotics) is necessary. This treatment serves to prevent inflammation in other organs.

To avoid complications, antibiotics may also be used to treat mild cases in high-risk groups. 

These high-risk groups include:   

• babies in the first year of life
• elderly people
• persons with congenital or acquired immunodeficiency
• patients with known damage to the heart valves or blood vessels.