Chris never thought that his pet iguana would make him sick. But when he started having a fever, abdominal cramps, and diarrhea, the doctor diagnosed him with an infection called salmonellosis and said that the iguana may have been the cause.
It's not just pets like iguanas and turtles that carry the Salmonella bacteria. Sometimes, these bacteria can find their way into foods. And recent food poisoning outbreaks involving tomatoes show that these foods aren't always animal products.
What Is Salmonellosis?
An infection with Salmonella bacteria usually affects the gastrointestinal system (the stomach and intestines) in humans. In more severe cases, Salmonella can spread to the blood, the bones, or even to the fluid around the brain, but these types of infection are less common.
An American scientist named Daniel E. Salmon is credited with the discovery of the Salmonella family of bacteria in the late 1800s. Since then, scientists have identified more than 2,400 types of Salmonella bacteria. They've also figured out where Salmonella live, how they spread to humans, and how to reduce their spread among the general public. Even so, each year the United States has about 40,000 cases of salmonellosis. And many more cases go unreported.
Salmonella bacteria are often found in the feces (poop) of some animals, particularly reptiles. Iguanas, for example, carry Salmonella marina. People who have these animals as pets are at more risk of getting salmonellosis because the bacteria from a reptile's feces can get on its skin. Then, when people handle the reptiles, they get the bacteria on their hands. (Hand washing is a good way to reduce the risk of getting salmonellosis.)
Other strains of Salmonella can spread to people in foods that have come into contact with infected animal feces. These exposures happen when foods such as poultry, eggs, and beef are not cooked enough. Fruit and vegetables can also become contaminated from feces in the soil or water where they are grown.
If fruit and vegetables are not washed thoroughly before they are eaten, they can spread Salmonella. The bacteria can also be spread through prepared foods if infected food handlers do not wash their hands properly after using the bathroom.
Who Is at Risk?
Lots of different things influence whether someone will be infected, including the person's age, general health, and immune system strength. Whether a person becomes sick or not can also depend on how many bacteria enter the digestive system.
People who are more likely to become ill from Salmonella include:
- young children and infants (their developing immune systems have a harder time fighting off the infection)
- older people
- those with weakened immune systems (such as people with HIV and those with sickle cell anemia)
- people who take cancer drugs
- people who take antacids or stomach acid suppression medication
In these higher risk groups, Salmonella is more likely to invade beyond the gastrointestinal tract and cause bacteremia (bacteria in the bloodstream). From there the bacteria can spread deeper into the body and cause more serious diseases, like meningitis.
What Are the Symptoms?
Symptoms of salmonellosis can include diarrhea that may be bloody, abdominal cramping and pain, and fever. These symptoms can take anywhere from 6 to 72 hours to appear after someone ingests the bacteria. Not everyone who swallows the bacteria will become ill. In most people, the illness lasts 4 to 7 days once symptoms begin.
Some strains of Salmonella can cause a more serious form of the disease known as typhoid or enteric fever. The symptoms of typhoid fever can include a prolonged fever, abdominal pain, headache, tiredness, a distinct rash, constipation or diarrhea, and a change in mental state. Typhoid fever is rare in the United States, but it can be common in developing countries.
What Can You Do to Protect Yourself and Others?
- Wash your hands. Good hygiene is important if you want to reduce your risk of getting salmonellosis and other food-borne illnesses. You can help prevent salmonellosis by encouraging your family to wash their hands thoroughly and frequently, particularly after going to the bathroom and before preparing food.
- Be cautious with pets, especially reptiles. Wash your hands thoroughly after touching them or cleaning their cages. Small children should not have reptiles, especially turtles, as pets.
- Be careful about food preparation. Because the bacteria appear most often in animal foods, avoid eating raw or undercooked eggs, poultry, or meat. Proper cooking will kill Salmonella, so poultry and meat should be cooked to the proper temperature.
Eggs can carry Salmonella bacteria both inside and outside the shell. Infection from contamination outside the shell is much less common today because egg producers follow strict procedures for cleaning and inspecting eggs. But another form of Salmonella infection can contaminate eggs before the shells are formed. Your best bet is to avoid eating raw or undercooked eggs, like sunny-side up or poached eggs with a soft center.
Unpasteurized milk and juices can also be contaminated, so stick with pasteurized.
- Avoid cross-contamination. When raw meat or eggs touch other food, it can lead to salmonellosis. And meat or eggs don't have to touch the food directly — sometimes cutting boards, counters, or utensils can transfer the bacteria from raw meat to foods like fruits and vegetables. To protect against this, keep uncooked meats and eggs separate from all other foods, cooked or raw. Avoid cutting raw meat with a knife and then using the unwashed knife to cut another food you are preparing — use a clean knife. And when you're done preparing raw meat, wash your hands, cutting boards, counters, and knives thoroughly with soap and hot water.
If you're planning to travel overseas — especially to a developing country — be sure to receive a typhoid vaccine before traveling if it is recommended. And once you're there, be cautious about drinking nonbottled drinks and eating foods sold by vendors on the street.
How Is Salmonellosis Treated?
If you think you may have salmonellosis, make an appointment to see your doctor. Because many different illnesses can cause similar symptoms, the doctor may send a stool (poop) sample to the lab for testing.
If you do have salmonellosis and the infection is not severe (that is, it has not spread beyond the gastrointestinal system), your doctor will probably let you get better on your own.
The doctor probably will not give you antibiotics unless you have a severe infection or you're in a high-risk group and unable to fight off the infection. Antibiotics do not appear to help a healthy person whose infection is not severe — and may actually lengthen the amount of time the person will carry the bacteria. Some people with salmonellosis may have to stay in the hospital to be treated for dehydration (an abnormally low level of fluid in the body), which can be a complication of any type of diarrhea.
A severe Salmonella infection will require further testing to determine the specific type behind the illness and which antibiotics can be used to treat it.
People who are infected with Salmonella may still be contagious from several days to several weeks after they've been infected — even if their symptoms have disappeared or they've been treated with antibiotics. So while you recover, be sure to wash your hands frequently and don't share your food or drinks with anyone. And if you work in a restaurant or your work involves handling food, check with your doctor before returning to work.
What Can I Do to Help Myself Feel Better?
Because any diarrhea can lead to dehydration — and because the diarrhea caused by Salmonella can be severe — drink plenty of water or drinks that contain electrolytes (such as sports drinks).
You may be tempted to treat yourself with anti-diarrheal medicines, but they're not usually recommended for people with salmonellosis. They can make the infection last longer, so be sure to check with your doctor first. If you have a fever, you can take acetaminophen or ibuprofen to reduce your temperature if your doctor says it's OK.
Reviewed by: Joel Klein, MD
Date reviewed: September 2011