Reptile-associated salmonellosis in Minnesota

A recent paper in Zoonoses and Public Health (Whitten et al, 2014) describes reptile-associated salmonellosis cases in Minnesota between 1996-2011. Like similar reports, the data underestimate the problem because it’s thought that for every documented case, approximately 30 cases go undiagnosed. Regardless, there are some useful findings.

Twelve to 30 cases of reptile-associated salmonellosis were identified in the state each year. That represented  about 3.5% of all sporadic (non-outbreak-associated) cases.

  • This is lower than is often reported, but Minnesota is also known to have one of the lowest pet ownership rates among states, which might account for this discrepancy, at least in part.

Kids bore the brunt of disease (as is normal), with the median age of victims being 11 years. 17% were less than one year of age, 31% were less than five years of age, and 67% were under 20.

  • The very young kids presumably had little or no direct contact with reptiles. This highlights the fact that living in the house with a reptile is a risk factor, even if there’s no direct contact. That’s why reptiles shouldn’t be in the house if there are high risk people present (i.e. kids less than five years of age, elderly individuals, pregnant women, immunocompromised individuals). Just trying to keep the high risk people from having contact with the reptile isn’t enough.

23% of cases had to be hospitalized. Fifteen (5%) had invasive infections, where Salmonella made it out of the intestinal tract and into the rest of the body.

  • These types of infection are a major concern, and the report included one case where the bacterium was found in the cerebrospinal fluid (indicating the person presumably had Salmonella meningitis).

Fortunately, none died.

Over half of the people who got sick and who were asked (i.e. not including the young kids) reported knowing that reptiles can be sources of Salmonella.

Almost half reported exposure to a lizard, with 20% reporting snake contact, 19% reporting turtle contact and some reporting contact with more than one type of reptile.

A quarter of those who reported turtle contact and indicated the size of the turtle said the turtle was less than four inches in length.

  • That’s relevant because it’s illegal to sell turtles that small in the US.  The rule was put in place due to the increased risk of kids handling small turtles and getting exposed to Salmonella. The finding isn't surprising, though, since this law is widely ignored.

Some people consented to having their reptile tested. 86% of the tested reptiles were shedding Salmonella at the time the follow-up was performed. 96% of those were the same strain that caused disease in the person.

Overall, not a lot has changed, which is concerning. There’s a risk of disease with any pet contact, but reptiles are undeniably high risk. We’ll never completely eliminate the problem, but logical pet ownership and animal management are needed to reduce the risk. A good start is getting young kids away from reptiles. Reptiles can make great pets… but not for young kids, and not without some risk.

Salmonella from bearded dragons...Canadian style

Not surprisingly (since bacteria don't respect borders), the Salmonella Cotham outbreak in the US associated with bearded dragons has also affected people in Canada. Nine cases of human salmonellosis associated with this rare Salmonella strain have been identified, many with a link to bearded dragons.

It's not particularly remarkable, but should be yet another reminder of the need to take care with reptiles, because they are such common carriers of Salmonella.  Remember that basic hygiene and common sense (like keeping reptiles away from any and all food preparation areas, like the kitchen) go a long way to reducing the risk of disease transmission from these critters.  High-risk individuals (young children, elderly, pregnant or immunosuppressed) need to be extra careful, or ideally just stay away from reptiles and other high-risk animals.

Salmonella outbreak from bearded dragons

The US CDC is reporting yet another multistate Salmonella outbreak linked to reptiles. This one is an outbreak of Salmonella Cotham that, as of April 21, has infected at least 132 people in 31 states.

The story is pretty similar to other reptile-associated Salmonella incidents.

58% of infected individuals are kids five years of age or younger.

  • That’s presumably a result of both higher risk contact by young kids (especially kissing reptiles) and the fact that young kids are at increased risk of getting sick when exposed to the bacterium.

42% of infected people have been hospitalized.

  • That’s a pretty high number compared to many other outbreaks. However, the actual overall hospitalization rate is probably lower, since it’s likely that many people had mild infections that were not diagnosed. Fortunately, no one died.

This Salmonella type is pretty rare, which makes it easier to trace it to a specific source. The investigation in this case traced it back to bearded dragons purchased as pets from a variety of stores in different states. Further investigation of the source is ongoing, and breeders that supplied the pet stores are being identified.

Of particular concern here was the presence of resistance to ceftriaxone, an important antibiotic, in a strain from at least one person. That’s something we don’t want spreading, since ceftriazone is often used to treat people with serious Salmonella infections.

Bearded dragons have a lot of personality (for reptiles), and are interesting little critters, so they’ve become popular pets. Like all other reptiles, they pose a risk of Salmonella exposure, and they shouldn’t be in households with high-risk individual (i.e. kids less than five years of age, elderly individuals, pregnant women, immunocompromised individuals). People who own "beardies" should use good hygiene practices and a solid dose of common sense to reduce the risk of salmonellosis. 

More information about Salmonella and reptiles is available on the Worms & Germs Resources - Pets page.

Things not to do with reptiles

I would have thought this would fall under the realm of common sense, but as the saying goes: Common sense is like deodorant, the people that need it the most don’t use it.

A recent report out of Scotland is warning people not to kiss their pet reptiles, in response to four people who were hospitalized with salmonellosis after kissing bearded dragons, and other reptiles.

Reptile-associated salmonellosis is a major concern, and while there are ways to make reptile ownership very safe for most people, some risk will always remain. Certain behaviours will increase that risk. A large percentage of healthy reptiles have Salmonella in their intestinal tracts, and anything that’s in the intestinal tract ends up in the animal’s habitat and on its skin. Kissing reptiles is an obvious way to be exposed to this bacterium, which can cause serious disease in some situations.

Among the report's recommendations are:

  • Families that own a bearded dragon or similar reptiles are advised to consult their doctor if they become ill with symptoms of fever, vomiting, abdominal pain and/or diarrhoea.
  • They should also inform their GP that they keep a reptile. Children are particularly at risk because they like to stroke and handle pets.
  • NHS Forth Valley have also issued a guide for pet owners to reduce the risk of catching Salmonella from lizards, which includes supervising children to make sure they do not put the animal, or objects it has been in contact with, near their mouths.
  • It also recommended washing hands with soap and water immediately after handling a reptile, its cage or any other equipment, keeping a reptile out of rooms where food it prepared or eaten, and disposing of droppings and waste water down a toilet, rather than in a sink or bath.

Just common sense.

More information about reptiles and Salmonella can be found on the Worms & Germs Resources - Pets page.

Salmonella in baby from pet reptile

.A five-month-old Britich baby was hospitalized with salmonellosis that was presumably acquired from a family pet. The baby developed severe diarrhea and was rushed to hospital. Fortunately, the child has recovered, something that's far from assured in such cases, since salmonellosis can be life-threatening in infants.

As expected, an investigation followed the diagnosis of salmonellosis. Typically, these investigations focus on food and animal contact, and since this family had a bearded dragon (see picture) and tortoises, the investigation honed in on the reptiles. Reptiles are high risk for Salmonella shedding and are commonly implicated in human infections. Further, the type of Salmonella that infected the infant, S. Pomona, is commonly associated with reptiles. It doesn't sound like they've confirmed that the same strain of Salmonella was present in the reptiles, but I assume that testing is underway.

Reptiles should not be present in households with infants. It doesn't matter if the animal never leaves its enclosure, because while the critter may not leave the enclosure, Salmonella will.

In low risk households (households without kids less than five years of age, elderly persons, pregnant women or immunocompromised individuals), good management practices can be used to minimize the risk of transmission of Salmonella, but given the potentially fatal nature of salmonellosis in infants and other high-risk individuals, these precautions are not adequate in high-risk households. While reptiles can be great pets, they're just not worth the risk in some situations.

Bearded dragon leads to gravy Salmonella contamination

No, not gravy made from bearded dragons (a type of reptile), but foodborne Salmonella with a link to the reptile.

Reptiles are an important source of Salmonella, which is why standard guidelines recommend that high-risk people (e.g. children less than 5 years of age, elderly individuals, people with compromised immune systems, pregnant women) not have contact with reptiles or have them in the house. A report in Zoonoses and Public Health (Lowther et al 2011) highlights another possible risk.

The report describes a Salmonella outbreak that was traced back to a potluck dinner. Nineteen cases were identified, 17 primary cases (people that attended the dinner) and two secondary cases (household members of people that attended the dinner). Overall, 29% of people that attended the dinner got sick. A further 18 people had some intestinal disease but strictly speaking didn't fit the definition for a case (however it is suspected that they were part of the outbreak). Salmonella subspecies IV (a type mainly associated with reptiles) was isolated from the stool of five people, confirming the occurrence of an outbreak.

As is typical, food consumption history was evaluated. Sixteen of the 17 primary cases reported consuming turkey gravy, which was a statistically higher proportion than that of people who did not get sick. The gravy was made at the private home of a person who didn't attend the dinner. This was the only home of the people involved where reptiles were kept. Two healthy bearded dragons lived in the house, in a terrarium in the living room.

The investigation focused on the reptiles, since the Salmonella strain found is typically associated with reptiles, and the turkey (the source of the gravy) had no evidence of Salmonella contamination based on testing. Samples from the environment of the household where the gravy was made were collected, and two types of Salmonella were identified. One of these Salmonella types (Salmonella Labadi, which was different from the outbreak strain) was isolated from one of the bearded dragons, as well as the inside and outside of the terrarium glass, other terrarium surfaces, surfaces around the terrarium, the bathroom sink drain and kitchen sink drain.

A common question that comes up when people have reptiles and high risk people in the house is "If I don't take the critter out of the cage, I should be ok, right?" Unfortunately, that's not true. Human Salmonella infections have been clearly identified in situations where reptiles don't leave the terrarium because (as was the case here), while the reptile may not leave the terrarium, Salmonella often does.

The person who made the gravy said that the bearded dragons had not been out of the terrarium when food was being prepared. A child was responsible for feeding the reptiles and cleaning the terrarium, and was supposed to use the bathroom for terrarium cleaning. However, it was reported that the reptiles' dishes "might have" been cleaned in the kitchen sink during the the day period when food was being prepared for the party.

The overall conclusion was that this outbreak "probably resulted from environmental contamination from bearded dragon faeces." It's a reasonable conclusion. Even though the same Salmonella strain wasn't found in the reptile, it makes sense because the reptiles were the most likely source of environmental contamination in the household, and that was the most likely source of the foodborne contamination. Reptiles can shed various Salmonella strains and they can shed intermittently. It takes multiple samples over time to get a real idea of the scope of Salmonella shedding, and I assume that one or both of these reptiles were shedding the outbreak strain at some point.

How can something like this be prevented, since the standard recommendation of having high risk people avoid contact with reptiles doesn't apply to this type of situation?

  • Good hygiene practices should be used when handling reptiles and their environments. In particular, there should be proper attention to hand hygiene after contact with reptiles or their cages.
  • Reptiles should not be allowed in the kitchen. Ever.
  • Food and water bowls should not be cleaned in kitchen sinks. Terrariums should not be cleaned in kitchen sinks. Ideally, they shouldn't be cleaned in bathroom sinks either. (If possible they should be cleaned outdoors with a hose.)
  • Good food handling practices are critical. Here, gravy wasn't re-heated to a high enough temperature to kill the contaminating Salmonella. Adequate re-heating would have prevented this outbreak.