Salmonella Food Poisoning (Salmonellosis)

What is Salmonella food poisoning?

          Salmonella infection, or salmonellosis, is sometimes referred to as Salmonella food poisoning. Salmonella are a type of bacteria that have been known to cause illness for over 125 years. The organism is named for a scientist named Daniel Elmer Salmon, who discovered the bacteria. Salmonellosis is a food-borne infection typically caused by consumption of contaminated foods. There are about 42,000 cases of salmonellosis reported each year in the U.S., but it is estimated to cause over 1 million illnesses per year. Because the illness is not always reported or diagnosed, it is estimated that the actual number of infections may be much higher than this.
Different types of the Salmonella bacteria can cause the illness. The two most common types in the U.S. are S. typhimurium and S. enteritidis. Specific strains of the bacteria can be responsible for outbreaks of the disease. For example, an outbreak in 2013-2014 was linked to multidrug-resistant Salmonella Heidelberg. This strain and some other strains have become resistant to many drugs traditionally used to treat the infection, posing a risk to public health.
Some types of Salmonella bacteria cause typhoid fever, a serious illness that occurs most often in nonindustrialized areas of the world.

What causes Salmonella outbreaks? How does Salmonella spread?

          Poultry, beef, milk, and eggs may contain Salmonella bacteria, since the bacteria live in the intestines of humans and animals. Thorough cooking of these foods destroys the bacteria.
Foods, including vegetables and fruits, may also be contaminated during handling or processing of the food, and this is another common source of outbreaks. For example, food may be contaminated by the feces of infected people or animals or from the unwashed hands of a person handling or preparing the food.
Small rodents such as hamsters, as well as baby chicks and ducklings, may also carry the bacteria, and contamination of food after handling these animals may also result in salmonellosis. Reptiles may also harbor Salmonella bacteria. In the 1970s, outbreaks were associated with baby turtles kept as pets. Further, the infection may be spread by contaminated surfaces (such as cutting boards) that have had contact with contaminated foods.
Contaminated foods usually look and smell normal. Over the past years, outbreaks of salmonellosis have been associated with a number of different foods, including chicken, cucumbers, alfalfa sprouts, ground beef, mangoes, peanut butter, and cantaloupe. These are just a few examples. An outbreak in Dec. 2014 was linked to contaminated bean sprouts.

What are risk factors for Salmonella food poisoning?

          Since foods contaminated with Salmonella are not obvious, anyone may consume contaminated foods. Owning pets such as small rodents, chicks, ducklings, turtles and some other reptiles, and some birds may increase the risk of coming in contact with Salmonella bacteria. People who are exposed to many people, such as those living in group housing, may have an increased risk. Children under 5 years of age have the highest reported incidence of infection.
People with medical conditions that lead to immune suppression are at risk for a more severe illness when they do become infected.

What are symptoms and signs of Salmonella poisoning?

         Symptoms usually begin 12-72 hours after infection. Diarrhea, abdominal cramping, and fever are common symptoms. The diarrhea is typically loose and not bloody. Nausea, vomiting, headache, and muscle aches may occur. The symptoms usually go away on their own after four to seven days.

Is Salmonella contagious?

          Salmonella food poisoning is usually acquired from eating contaminated foods. It is possible to spread the infection to others through fecal-oral contamination, meaning that fecal material contaminates the hands of an infected person who then contaminates foods that are consumed by others.

What is the incubation period for a Salmonella infection?

          Symptoms usually begin 12-72 hours after infection.

What is the contagious period for salmonellosis?

          Those with Salmonella infection can be contagious for days to weeks, even after symptoms have disappeared.

How do physicians diagnose Salmonella food poisoning?

          Many infections can cause similar symptoms, so diagnosis of Salmonella infection requires identification of the organism in a stool sample from the affected person. Specific tests can be done to identify the exact type of Salmonella responsible for an infection.

What is the treatment for Salmonella food poisoning?

          In most cases, the symptoms resolve on their own without treatment within four to seven days. Taking plenty of fluids is essential to replace fluid lost by diarrhea to prevent dehydration. People with severe illness or who are unable to take oral liquids may need intravenous fluids. Antibiotics have been shown to prolong the time period in which the bacteria are present in the stool and are therefore not recommended for most cases. People with severe illness, those at high risk for complications (such as the elderly or infants), or those with decreased immune function may require treatment with antibiotics.

What are complications of Salmonella food poisoning?

          Complications can include dehydration from vomiting and diarrhea. Spread of the infection to the bloodstream is a further possible complication. This is most likely to occur in people with suppressed immune function. The elderly and very young are also at increased risk for complications.
An uncommon complication called reactive arthritis involves the development of joint pains, irritation of the eyes, and pain on urination. Reactive arthritis may persist for months to years and can lead to chronic arthritis.

What is the prognosis of Salmonella food poisoning?

          Most cases of salmonellosis resolve completely without long-term complications, but bowel habits may be abnormal for months. About 450 people die from salmonellosis each year in the U.S.

Is it possible to prevent Salmonella food poisoning?

         There is no vaccine available to prevent Salmonella infection. However, one can take the following steps to reduce the likelihood of getting the infection:

1. Wash hands thoroughly after using the bathroom.
2. Cook meats and eggs thoroughly.
3. Do not consume raw eggs or unpasteurized milk.
4. Wash hands and kitchen surfaces with soap and water after contact with raw meat or eggs.
5. Do not allow uncooked meats to come in contact with other foods in the kitchen, including utensils and work surfaces that will be used to prepare other foods.
6. Wash hands thoroughly after contact with animal feces and after all contact with reptiles, birds, and small rodents.
7. Chill foods after serving and when transporting from place to place.

 

 SOURCES:

1. Klochko, Alena. "Salmonellosis." Medscape.com. Sept. 25, 2014. <http://emedicine.medscape.com/article/228174-overview>.

2. United States. Centers for Disease Control and Prevention. "Salmonella." Sept. 4, 2015. <http://www.cdc.gov/salmonella/>.