The cluster was detected in July 2020 by PulseNet, the national molecular subtyping network for enteric disease surveillance. The isolates were closely related genetically to each other by whole genome sequencing (WGS) analysis and related to isolates from two previous outbreaks of Salmonella Typhimurium infections linked to pet hedgehogs.

There were 49 patients identified in 25 states, including 14 in children younger than 5 years old. Eleven of 42 patients with available information were hospitalized. Among 36 interviewed patients, 30 reported hedgehog contact before becoming ill.

Hedgehogs carrying Salmonella bacteria can appear healthy and clean and show no signs of illness. Salmonella bacteria are shed in their droppings and can easily contaminate their bodies and anything in the area where hedgehogs live and roam.

Investigating: Whole Genome Sequencing and interviews
These cases were defined by having an isolation of Salmonella Typhimurium closely related by WGS to the outbreak strain in specimens from patients with illness onset from April to November 2020.

Animal and environmental sampling of hedgehog enclosures was conducted at some patient residences. Hedgehog purchase locations were contacted to identify a possible common source or supplier of hedgehogs.

Samples collected from hedgehogs in patients’ homes in New York and North Dakota and from a hedgehog habitat in California yielded the outbreak strain of Salmonella Typhimurium. Isolates were closely related genetically. The Public Health Agency of Canada identified 31 cases highly related by WGS to U.S. cases, also traced to hedgehog contact.

Hedgehog purchase locations were available for 20 of the 36 patients interviewed and included U.S. Department of Agriculture licensed breeders, unlicensed breeders, pet stores and online sales. Traceback graphic can be seen here. No common hedgehog supplier was identified as the single source for either the U.S. or Canadian outbreaks.

Among 27 identified U.S. hedgehog sources, six breeders were interviewed. All six breeders reported that they provide educational information to new owners when they purchase hedgehogs; four of the six provide information on prevention of disease transmission from pets to humans. Five of the six breeders reported that they work with a veterinarian or veterinary clinic. Only one breeder reported having a protocol in place for testing hedgehogs for Salmonella.

This particular outbreak strain of Salmonella has continued to cause disease despite targeted outreach to hedgehog breeders and industry groups during two previous outbreaks with the strain linked to hedgehogs. Officials say this highlight that additional efforts are needed to reduce the prevalence and spread of Salmonella among hedgehogs and to limit transmission from hedgehogs to humans.

Preventing Salmonella infections
Prevention and control of Salmonella in hedgehogs is complicated because of asymptomatic carriage and persistent or intermittent fecal shedding; however, Salmonella mitigation is possible through prevention and control measures focused on good sanitation and husbandry practices. To prevent future outbreaks linked to contact with pet hedgehogs, breeders and veterinarians need to educate owners on the risk and prevention of Salmonella transmission from hedgehogs and advise that hedgehogs might be inappropriate pets for children younger than 5 years old.

The pet industry, veterinarians and public and animal health officials could collaborate to help prevent disease transmission to humans by establishing and disseminating information on ways to reduce the prevalence of Salmonella in hedgehog breeding colonies intended for use in the pet industry.

The CDC provides the following recommendations for protecting yourself and others, especially children, from contact with Salmonella bacteria that hedgehogs may carry:

Wash your hands:

Wash your hands for at least 20 seconds with water and soap right after touching hedgehogs or anything in the area where they live and roam. This includes after handling pet food and treats.
Thorough hand-washing is especially important before preparing, serving or eating food, drinks or preparing baby bottles. Also, always wash hands right after handling or cleaning up after any pets.
If soap and water are not readily available, use hand sanitizer until you are able to wash your hands thoroughly with soap and water.
Adults should supervise young children when washing hands.
Pet owners should make sure friends and family wash their hands after touching their pet hedgehogs.

Practice safe handling of hedgehogs:

Do not let hedgehogs in areas where food or drink is prepared, served or stored, such as kitchens or outdoor patios.
Do not snuggle or kiss hedgehogs, touch your mouth, or eat or drink around hedgehogs.
Some hedgehogs may get ill from a Salmonella infection and can have diarrhea.
If your hedgehog has diarrhea, see your pet’s veterinarian immediately.

Clean up properly when handling hedgehogs:

To prevent cross-contamination, do not bathe hedgehogs in the kitchen sink or in bathroom sinks or bathtubs. Hedgehogs should be bathed in a small plastic tub or bin that is dedicated for hedgehog use only.
Clean any equipment or materials associated with caring for hedgehogs outside the house, such as cages or feed or water containers or items used for bathing.

Be careful with children and hedgehogs:

Young children are especially at risk for illness because their immune systems are still developing and because they are more likely than others to put their fingers or other items into their mouths.
Children younger than 5 years of age should not be allowed to touch or eat pet food, treats, or supplements and should be kept away from hedgehog feeding areas to prevent illness and injury.

About Salmonella infections
Salmonella bacteria is microscopic and therefore cannot be seen with the naked eye. Anyone can become sick with a Salmonella infection. Infants, children, seniors, and people with weakened immune systems are at higher risk of serious illness because their immune systems are fragile, according to the CDC.

Anyone who has developed symptoms of Salmonella infection should seek medical attention. Sick people should tell their doctors about the possible exposure to Salmonella bacteria because special tests are necessary to diagnose salmonellosis. Salmonella infection symptoms can mimic other illnesses, frequently leading to misdiagnosis.

Symptoms of Salmonella infection can include diarrhea, abdominal cramps, and fever within 12 to 72 hours after exposure to the bacteria. Otherwise, healthy adults are usually sick for four to seven days. In some cases, however, diarrhea may be so severe that patients require hospitalization.

Older adults, children, pregnant women, and people with weakened immune systems, such as cancer patients, are more likely to develop a severe illness and serious, sometimes life-threatening conditions.

Some people get infected without getting sick or showing any symptoms. However, they may still spread the infections to others.

(To sign up for a free subscription to Food Safety News, click here.)