Salmonella Food Poisoning (Salmonellosis)

Picture of Salmonella

• Salmonella bacteria live in the intestinal tract of humans and animals and are excreted in feces. Poultry, beef, milk, and eggs all can contain Salmonella bacteria.
• Salmonella infection is a foodborne illness that occurs from consumption of raw meats and eggs, contaminated dairy foods such as unpasteurized (raw) milk, or fruits and vegetables contaminated by food handlers.
• A Salmonella bacterial infection causes gastrointestinal symptoms, including
  • diarrhea,
  • abdominal pain,
  • nausea, and
  • vomiting.
• Symptoms develop within 12-72 hours and typically last four to seven days.
• The two most common types in the U.S. are S. typhimurium and S. enteritidis. Some types of Salmonella bacteria cause the illness known as typhoid fever.
• In most cases, no specific treatment is needed other than adequate hydration.
• Most cases of salmonellosis are not life-threatening and resolve on their own without complications.
• People at risk for complications or those with particularly severe illness or a weakened immune system may need antibiotic therapy.
• There is no vaccine to prevent Salmonella infection.
• Salmonella may infect reptiles, rodents, and birds. Contact with these animals increases the likelihood of getting the infection.
• People may prevent infection by following established food safety practices, including attention to hygiene during food preparation and handling of animals.

Salmonella infection, or salmonellosis, is another name for Salmonella food poisoning. Salmonella are a type of bacteria known to cause food-borne 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. Salmonella causes an estimated 1 million food-borne illnesses every year in the U.S. and about 19,000 hospitalizations.

Different types (called serotypes or serovars) of the Salmonella bacteria can cause the illness. The two most common serotypes 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 serotype 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 (S. typhi) cause typhoid fever, a serious illness that occurs most often in nonindustrialized areas of the world.

Salmonella illness causes an inflammation of the gastrointestinal tract; this is known as gastroenteritis.

• Symptoms of Salmonella poisoning 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
• Muscle aches

The symptoms usually go away on their own after four to seven days.

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, bean sprouts, ground beef, mangoes, peanut butter, and cantaloupe. These are just a few examples. An outbreak in February 2016 caused by the strain Salmonella muenchen was linked to contaminated alfalfa sprouts. In 2017, an outbreak was linked to papayas from Mexico. A breakfast cereal known as Honey Smacks caused an outbreak in 2018.

Since foods contaminated with Salmonella are not obvious, anyone may consume contaminated foods. Owning pets such as small rodents, chicks, ducklings, small 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. Young 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.

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

Symptoms usually begin 12-72 hours after infection with salmonella.

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

Salmonellosis may be treated by

• primary care doctors,
• pediatricians,
• emergency medicine doctors, or
• internal medicine doctors.

In severe or complicated cases, other doctors may be consulted, including gastroenterologists or critical care specialists.

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.

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 with risk factors for complications (such as the elderly or infants), or those with a weakened immune function may require treatment with antibiotics.

Most cases of salmonellosis resolve completely without long-term complications, but bowel habits may be abnormal for months. About 380 people die from salmonellosis each year in the U.S.

Complications of Salmonella food poisoning 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.

There is no vaccine available to prevent Salmonella infection. However, one can take the following steps to help ensure good hygiene and food safety, reducing 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.