Salmonellosis (patient information)
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Assistant Editor(s)-in-Chief: Laura Linnemeier; João André Alves Silva, M.D. [2] Jolanta Marszalek, M.D. [3]
Overview
Salmonellosis is one of the most common and widely distributed foodborne diseases and is caused by the bacteria salmonella. There are many different kinds of Salmonella bacteria. Salmonella are usually transmitted to humans by eating foods contaminated with animal feces. Symptom onset commonly occurs 6 to 72 hours after ingestion of the bacteria. Symptoms of salmonellosis include: fever, abdominal pain, diarrhea, nausea and vomiting. These are relatively mild, and patients make a recovery without specific treatment in most cases. However, in some groups, such as children, elderly and immunocompromised patients, complications may occur. Salmonellosis may be diagnosed following laboratory tests that identify Salmonella in the stool of infected persons. Salmonellosis usually resolves in 5-7 days and often does not require treatment other than oral fluids and electrolyte replacement, yet antibiotic treatment may be required in certain cases. Since there is no vaccine against salmonella, preventive measures for public and travelers, food handlers and producers of fruits and vegetables should be applied.
What are the symptoms of Salmonellosis?
The onset of disease symptoms occurs 6 - 72 hours (usually 12-36 hours) after ingestion of salmonella. It is usually characterized by acute onset of:
The illness usually lasts 4 to 7 days. Symptoms of salmonellosis are relatively mild and patients make a recovery without specific treatment in most cases. However, in some cases, particularly in the very young and in the elderly patients, the associated dehydration can become severe and life-threatening. The diarrhea may be so severe that the patient needs to be hospitalized. In these patients, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites. Unless the person is treated promptly with antibiotics, death may occur.
What causes Salmonellosis?
Salmonellosis is caused by salmonella. For salmonella species, over 2 500 different strains (called "serotypes" or "serovars") have been identified to date. Salmonella is a ubiquitous and hardy bacteria that can survive several weeks in a dry environment and several months in water. The bacteria live in the intestinal tract of humans and other animals, including birds.
Transmission
Salmonella are usually transmitted to humans by eating foods contaminated with animal feces. Contaminated foods usually look and smell normal. Contaminated foods are often of animal origin, such as beef, poultry, milk, or eggs, but any food, including vegetables, may become contaminated.
Food may become contaminated by the hands of an infected food handler who did not wash hands with soap after using the bathroom.
Salmonella may also be found in the feces of some pets, especially those with diarrhea, and people can become infected if they do not wash their hands after contact with pets or pet feces. Reptiles, such as turtles, lizards, and snakes, are particularly likely to harbor Salmonella. Many chickens and young birds carry Salmonella in their feces.
Who is at highest risk?
Children are at highest risk to get salmonellosis. The rate of diagnosed infections in children less than five years old is about five times higher than the rate in all other persons.
Persons at risk of severe disease or complications, include:
- Children
- Elderly
- Immunocompromised persons
Salmonellosis is more common in the summer than winter.
Diagnosis
Many different kinds of illnesses can cause diarrhea, fever, or abdominal cramps. Determining that Salmonella is the cause of the illness depends on laboratory tests that identify Salmonella in the stool of an infected person. Once Salmonella has been identified, further testing can determine its specific type.
When to seek urgent medical care?
The illness usually lasts 4 to 7 days, and most persons recover without treatment. However, in some persons, the diarrhea may be so severe that the patient needs to be hospitalized. In these patients, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated promptly with antibiotics. The elderly, infants, and those with impaired immune systems are more likely to have a severe illness.
Treatment options
Salmonella infections usually resolve in 5-7 days and often do not require treatment other than oral fluids and electrolyte replacement. Persons with severe diarrhea may require rehydration with intravenous fluids.
Antibiotic therapy can prolong the duration of excretion of non-typhoidal Salmonella and is recommended only for patients with severe illness (e.g., those with severe diarrhea, high fever, bloodstream infection, or who need hospitalization) or those at risk of severe disease or complications, including young infants, older adults (over 65 years old) and immunocompromised persons. Antibiotics may include trimethoprim-sulfamethoxazole, or ciprofloxacin.
Some Salmonella bacteria have become resistant to antibiotics, largely as a result of the use of antibiotics to promote the growth of food animals, therefore, susceptibility testing can help guide appropriate therapy.
Where to find medical care for Salmonellosis?
Directions to Hospitals Treating Salmonellosis
Prevention of Salmonellosis
There is no vaccine to prevent salmonellosis.
Contact with Animals
- People should wash their hands after contact with animal feces.
- Because reptiles are particularly likely to have Salmonella, and it can contaminate their skin, everyone should immediately wash their hands after handling reptiles. Reptiles (including turtles) are not appropriate pets for small children and should not be in the same house as an infant.
- Salmonella carried in the intestines of chickens and ducklings contaminates their environment and the entire surface of the animal. Children can be exposed to the bacteria by simply holding, cuddling, or kissing the birds. Children should not handle baby chickens or other young birds.
- Everyone should immediately wash their hands after touching birds, including baby chicks and ducklings, or their environment.
Recommendations for the public and travelers
Prevention requires control measures at all stages of the food chain, from agricultural production, to processing, manufacturing and preparation of foods in both commercial establishments and at home.
- Ensure food is properly cooked and still hot when served.
- Avoid raw milk and products made from raw milk. Drink only pasteurized or boiled milk.
- Raw eggs may be unrecognized in some foods, such as:
- Homemade Hollandaise sauce
- Caesar and other homemade salad dressings
- Tiramisu
- Homemade ice cream
- Homemade mayonnaise
- Cookie dough
- Frostings.
- Avoid ice unless it is made from safe water.
- When the safety of drinking water is questionable, boil it or if this is not possible, disinfect it with a reliable, slow-release disinfectant agent.
- Wash hands thoroughly and frequently using soap, in particular after contact with pets or farm animals, or after having been to the toilet.
- Wash fruits and vegetables carefully, particularly if they are eaten raw. If possible, vegetables and fruits should be peeled.
- Cross-contamination of foods should be avoided. Uncooked meats should be kept separate from produce, cooked foods, and ready-to-eat foods. Hands, cutting boards, counters, knives, and other utensils should be washed thoroughly after touching uncooked foods. Hand should be washed before handling food, and between handling different food items.
Recommendations for food handlers
- Both professional and domestic food handlers should be vigilant while preparing food and should observe hygienic rules of food preparation.
- Professional food handlers who suffer from fever, diarrhea, vomiting or visible infected skin lesions should report to their employer immediately.
- The WHO Five Keys to Safer Food serve as the basis for educational programmes to train food handlers and educate consumers. They are especially important in preventing food poisoning. The Five Keys are:
- Keep clean
- Separate raw and cooked
- Cook thoroughly
- Keep food at safe temperatures
- Use safe water and raw materials
Recommendations for Producers of Fruits and Vegetables
- The WHO "Five keys to growing safer fruits and vegetables" is an educational manual for rural workers, including small farmers who grow fresh fruits and vegetables for themselves, their families and for sale in local market. It provides them with key practices to prevent microbial contamination of fresh produces during planting, growing, harvesting and storing.
- The five keys practices are:
- Practice good personal hygiene
- Protect fields from animal fecal contamination
- Use treated fecal waste
- Evaluate and manage risks from irrigation water
- Keep harvest and storage equipment clean and dry
What to expect (Outlook/Prognosis)?
The illness usually lasts 4 to 7 days, and most persons recover without treatment. However, in some persons, the diarrhea may be so severe that the patient needs to be hospitalized. In these patients, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated promptly with antibiotics.
Persons with diarrhea usually recover completely, although it may be several months before their bowel habits are entirely normal. A small number of persons with Salmonella develop pain 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. Antibiotic treatment does not make a difference in whether or not the person develops arthritis. Other possible complication is typhoid fever, a more serious disease caused by a certain strain of Salmonella, however, it is not common in the United States, frequently occurring in developing countries.