Centers for Disease Control and Prevention
(Frequently Asked Questions)
Salmonellosis is an infection with a bacteria called Salmonella. Most
persons infected with Salmonella develop diarrhea, fever, and abdominal cramps 12
to 72 hours after infection. 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
The Salmonella germ is actually a group of bacteria that can cause diarrheal
illness in humans. They are microscopic living creatures that pass from the feces of
people or animals, to other people or other animals. There are many different kinds
of Salmonella bacteria. Salmonella serotype Typhimurium and Salmonella
serotype Enteritidis are the most common in the United States. Salmonella has
been known to cause illness for over 100 years. They were discovered by a American
scientist named Salmon, for whom they are named.
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 stools of an infected person. These tests are
sometimes not performed unless the laboratory is instructed specifically to look for the
organism. Once Salmonella has been identified, further testing can determine
its specific type, and which antibiotics could be used to treat it.
Salmonella infections usually resolve in 5-7 days and often do not require
treatment unless the patient becomes severely dehydrated or the infection spreads from the
intestines. Persons with severe diarrhea may require rehydration, often with
intravenous fluids. Antibiotics are not usually necessary unless the infection
spreads from the intestines, then it can be treated with ampicillin, gentamicin,
trimethoprim/sulfamethoxazole, or ciprofloxacin. Unfortunately, some Salmonella
bacteria have become resistant to antibiotics, largely as a result of the use of
antibiotics to promote the growth of feed animals.
Persons with diarrhea usually recover completely, although it may be several months
before their bowel habits are entirely normal. 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. Antibiotic treatment does not make a difference in whether or not the person
later develops arthritis.
Salmonella live in the intestinal tracts of humans and other animals, including birds. 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 all foods, including vegetables may become contaminated. Many raw foods of animal origin are frequently contaminated, but fortunately, 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 feces of some pets, especially those with
diarrhea, and people can become infected if they do not wash their hands after contact
with these feces. Reptiles are particularly likely to harbor Salmonella and
people should always wash their hands 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.
There is no vaccine to prevent salmonellosis. Since foods of animal origin may be contaminated with Salmonella, people should not eat raw or undercooked eggs, poultry, or meat. Raw eggs may be unrecognized in some foods such as homemade hollandaise sauce, caesar and other salad dressings, tiramisu, homemade ice cream, homemade mayonnaise, cookie dough, and frostings. Poultry and meat, including hamburgers, should be well-cooked, not pink in the middle. Persons also should not consume raw or unpasteurized milk or other dairy products. Produce should be thoroughly washed before consuming.
Cross-contamination of foods should be avoided. Uncooked meats should be keep separate from produce, cooked foods, and ready-to-eat foods. Hands, cutting boards, counters, knives, and other utensils should be washed thoroughly after handling uncooked foods. Hand should be washed before handling any food, and between handling different food items.
People who have salmonellosis should not prepare food or pour water for others until they have been shown to no longer be carrying the Salmonella bacterium.
People should wash their hands after contact with animal feces. Since reptiles
are particularly likely to have Salmonella, 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.
Every year, approximately 40,000 cases of salmonellosis are reported in the United
States. Because many milder cases are not diagnosed or reported, the actual number
of infections may be twenty or more times greater. Salmonellosis is more common in
the summer than winter. Children are the most likely to get salmonellosis.
Young children, the elderly, and the immunocompromised are the most likely to have severe
infections. It is estimated that approximately 1,000 persons die each year with
It is important for the public health department to know about cases of salmonellosis. It is important for clinical laboratories to send isolates of Salmonella to the City, County, or State Public Health Laboratories so the specific type can be determined and compared with other Salmonella in the community. If many cases occur at the same time, it may mean that a restaurant, food or water supply has a problem which needs correction by the public health department.
Some prevention steps occur everyday without you thinking about it.
Pasteurization of milk and treating municipal water supplies are highly effective
prevention measures that have been in place for many years. In the 1970s, small pet
turtles were a common source of salmonellosis in the United States, and in 1975, the sale
of small turtles was halted in this country. Improvements in farm animal hygiene, in
slaughter plant practices, and in vegetable and fruit harvesting and packing operations
may help prevent salmonellosis caused by contaminated foods. Better education of
food industry workers in basic food safety and restaurant inspection procedures, may
prevent cross-contamination and other food handling errors that can lead to
outbreaks. Wider use of pasteurized egg in restaurants, hospitals, and nursing homes
is an important prevention measure. In the future, irradiation or other treatments
may greatly reduce contamination of raw meat.
The Centers for Disease Control and Prevention (CDC)
monitors the frequency of Salmonella infections in the country and assists the
local and State Health Departments to investigate outbreaks and devise control
measures. CDC also conducts research to better identify specific types of Salmonella.
The Food and Drug Administration inspects imported foods,
milk pasteurization plants, promotes better food preparation techniques in restaurants and
food processing plants, and regulates the sale of turtles. The FDA also regulates
the use of specific antibiotics as growth promotants in food animals. The US Department of Agriculture monitors the health of food
animals, inspects egg pasteurization plants, and is responsible for the quality of
slaughtered and processed meat. The US Environmental
Protection Agency regulates and monitors the safety of our drinking water supplies.
You can discuss any medical concerns you may have with your doctor or other heath care
provider. Your local City or County Health Department can provide more information
about this and other public health problems that are occurring in your area. General
information about the public health of the nation is published every week in the "Morbidity and Mortality Weekly Report",
by the CDC in Atlanta, GA. Epidemiologists in your local and State Health
Departments are tracking a number of important public health problems, investigating
special problems that arise, and helping to prevent them from occurring in the first
place, or from spreading if they do occur.
For more information contact:
Office of the Director, Mailstop C09
Division of Bacterial and Mycotic Diseases
National Center for Infectious Diseases
Centers for Disease Control
1600 Clifton Road
Atlanta, Georgia 30333
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