Salmonella infections in children linked to pet frogs

Robin Wulffson MD's picture
salmonella, pet frogs, African dwarf frog, salmonella enterocolitis

If you have pet frogs in your home, it would be advisable to take precautions when caring for them or consider another type of pet. According to a new government study, contact with the little hoppers carries a risk of a salmonella infection.

Researchers affiliated with the Centers for Disease Control and Prevention (CDC) and a number of federal and state agencies published their findings online in the journal Pediatrics on March 11. The researchers noted that amphibians are known salmonella carriers, no such outbreaks have been reported. Therefore, they conducted a study to determine whether the animals were indeed responsible for infections in humans. They investigated a nationwide outbreak of human Salmonella typhimurium infections occurring predominantly among children from 2008 to 2011.

The researchers designed a matched case-control study. Cases were defined as individuals with Salmonella Typhimurium infection yielding an isolate indistinguishable from the outbreak strain. Controls were individuals with recent infection with salmonella strains other than the outbreak train and matched to cases by age and geography. Environmental samples were obtained from patients’ homes; traceback investigations were conducted.

From January 1, 2008, to December 31, 2011, the investigators identified 376 cases from 44 states; 56/193 (29%) of the patients were hospitalized and none died. The average patient age was five years (range: under age 1 to 86 years). Of those individuals, 253, 367 were children under age 19. Among 114 patients interviewed, 69 (61%) reported frog exposure. Of patients who knew which type of frog they were exposed to, 44/56 (79%) reported African dwarf frogs, a type of aquatic frog. Among 18 cases and 29 controls, illness was significantly associated with frog exposure (67% cases versus 3% controls). Environmental samples from aquariums containing African dwarf frogs in eight patients’ homes, two African dwarf frog distributors, and a day care center were found to contain bacteria indistinguishable from the outbreak strain. Traceback investigations of African dwarf frogs from patient purchases converged to a common breeding facility for that amphibian. Environmental samples from the breeding facility yielded the outbreak strain.

The authors concluded that African dwarf frogs were the source of this nationwide pediatric predominant outbreak. They recommended that pediatricians should routinely inquire about pet ownership and advise families about illness risks associated with animals.

The California breeder linked to the outbreak briefly suspended distribution and cooperated with authorities. The CDC advises washing hands after touching the frogs' aquarium water and says young children should not clean aquariums. Wear gloves when handling the animal or its feces. Good hand washing is important.


About salmonella:

  • Salmonella enterocolitis is one of the most common types of food poisoning. It occurs when you swallow food or water that is contaminated with the salmonella bacteria. Any food can become contaminated if food preparation conditions and equipment are unsanitary.

You are more likely to get this type of infection if you have:

  • Eaten improperly prepared or stored food (especially undercooked turkey or chicken, unrefrigerated turkey dressing, undercooked eggs)
  • Family members with recent salmonella infection
  • Had a recent family illness with gastroenteritis
  • Been in an institution
  • Eaten chicken recently
  • In addition to amphibians, a pet iguana or other lizards, turtles, or snakes (reptiles are carriers of salmonella)
  • A weakened immune system
  • Approximately 40,000 people develop salmonella infection in the United States each year. Most patients are younger than 20. The highest rate occurs from July through October.

The time between infection and symptom development is 8 - 48 hours. Symptoms include:

  • Abdominal pain or cramping or tenderness
  • Chills
  • Diarrhea
  • Fever
  • Muscle pain
  • Nausea
  • Vomiting


  • The goal of treatment is to replace fluids and electrolytes lost by diarrhea. Electrolyte solutions are available without a prescription. Antidiarrheal medications are generally not given because they may prolong the infection. If you have severe symptoms, your doctor may prescribe antibiotics. People with diarrhea who are cannot drink anything due to nausea may need medical attention and intravenous fluids. This is especially true for small children. Fever and aches can be treated with acetaminophen or ibuprofen.
  • If you take diuretics, you may need to stop taking them during the acute episode, when diarrhea is present. Ask your health care provider for instructions.
  • Changing your diet while you have diarrhea may help reduce symptoms. This may include avoiding milk products and following a BRAT diet. BRAT stands for bananas, rice, applesauce, and toast. These are binding foods that make the stools firmer.
  • Infants should continue to breastfeed and receive electrolyte replacement solutions as directed by your healthcare provider.

Expectations (prognosis)

  • The outcome is usually good. In otherwise healthy people, symptoms should go away in 2 - 5 days.
  • The acute illness lasts for 1 - 2 weeks. The bacteria are shed in the feces for months in some treated patients.
  • Some people who shed the bacteria have a carrier state for 1 year or more after the infection.


  • Dehydration from diarrhea, especially in young children and infants, is a dangerous complication. Life-threatening meningitis and septicemia may also occur. Food handlers who become carriers can pass the infection along to the people who eat their food.

Reference: CDC


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