Saturday, July 31, 2010

Of Mice and Men . . . And Snakes and Salmonella

Frozen reptile feed fingered in multiple Salmonella outbreaks

People who keep pet snakes are a special breed. It takes a certain kind of person to use live critters as pet food.

Fortunately for many reptile owners, a couple of companies discovered that there was a market for frozen or freeze-dried reptile feed, in the form of mice, rats and chicks. Unfortunately, the entrepreneurs that filled this niche market have since learned what any microbiologist could have told them in a heartbeat.

Freezing does not kill Salmonella.

The latest company to find this out is MiceDirect (Cleveland, GA), whose "frozen reptile feed" has been linked to 30 or more cases of Salmonella Typhimurium infections in 17 states, including two victims in New York State. MiceDirect recalled the implicated frozen critters and has announced that "Products shipped after 07/24/2010, will be irradiated in a similar manner as raw food for human consumption in order to address the Salmonella issue associated with these products."

The recall encompasses product codes M-SP100, M-P100, M-PF100, M-F100, M-H100, M-W50, M-A50, M-JA25, R-P100, R-F50, R-PUP50, R-W50, R-S50, R-M20, R-L10,R-J5, R-C5, R-M3 followed by E9, F9, G9, H9, I9, J9, K9, L9 or A10, B10, C10, D10, E10, F10, G10 and whole frozen chicks in 25 count bags. Recalled products were distributed in 49 states (none were shipped to Hawaii) through pet stores and by mail order and direct delivery.

In contrast to the official recall notice, the explanation that is posted on the MiceDirect web site makes no mention whatsoever of the Salmonella outbreak that triggered the company's action. Instead, it gives the following explanation:
This is to inform you that MiceDirect has issued a voluntary recall. Over the years we have regularly tested our rodents for any potential issues. During one of these recent tests it was detected that a portion of our rodents may be potentially carrying Salmonella. Because of this we are offering a voluntary recall option to our customers.


This particular type of Salmonella cannot be passed to your reptile. Reptiles carry other specific strains.

  • Salmonella is common in almost all groups of both domestic and wild animals
  • Salmonella can make you sick, small children and frail or elderly people are more susceptible.
  • Washing your hands prevents this risk of illness from Salmonella. Please wash your hands when handling.

When handling raw product, such as rodents, chicken, pork, beef or any dead animal, it is very important to thoroughly wash your hands. Washing your hands should keep you from becoming sick in the event you come into contact with Salmonella.


Where did MiceDirect uncover the "Fact" that this strain of Salmonella Typhimurium cannot be passed to reptiles? And what difference does that make, anyway? It clearly can be – and has been – passed to humans.

Indeed, according to an article in the New York Times, frozen reptile food supplied by MiceDirect was responsible for a large and enduring outbreak of Salmonella Typhimurium illnesses in the United Kingdom that has sickened more than 400 people – two-thirds of them children less than 10 years old – since August 2008.

The UK's Health Protection Agency detected the appearance of the outbreak strain in December 2008, and followed its progress across England, Scotland, Wales and Northern Ireland. Patient interviews unearthed a link between the illnesses and exposure to pet reptiles – especially snakes. In most cases, the snakes had been fed frozen mice that had been imported from a single US company. And, notwithstanding MiceDirect's assurances, the outbreak strain was recovered from two snakes that belonged to outbreak victims.

The New York Times reports that, in May 2009, UK authorities advised the US Centers for Disease Control and Prevention (CDC) of the outbreak and of its link to MiceDirect. CDC, upon checking its database, found no matching US cases but says that it advised FDA of the British report.

The first US case was reported to CDC in January 2010. The agency realized in the spring that something was brewing, and began its investigation. In May, CDC notified FDA that an outbreak was in progress, but only established a link to MiceDirect at the beginning of July. FDA and CDC visited the MiceDirect facility on July 6th to inspect the location and take samples of the environment and the rodents. On July 21st, FDA notified MiceDirect that the agency had found Salmonella in the company's products and facility.

CDC has not yet posted an investigation report on its web site, but expects to do so in the near future. At that time, we'll learn the scope of the outbreak and more about the victims and the investigation.

The MiceDirect outbreak is not the first time that Salmonella-contaminated rodents were linked to an outbreak of human disease. Between December 2003 and September 2004, 28 people in 10 states were infected with Salmonella Typhimurium after being exposed to pet rodents, including mice and hamsters. Nor is it the first outbreak that has been linked to frozen reptile food.

From December 2005 to August 2006, 21 people in Minnesota, Michigan, Pennsylvania and Wyoming developed infections with Salmonella Typhimurium. Most of the victims reported exposure to snakes. Nineteen of the 21 outbreak victims were interviewed and seven of the 19 reported contact with frozen vacuum-packed rodents from a single Internet-based supplier located in Texas. Upon investigation, the Texas Feed and Fertilizer Control Service traced the rodents to a single, unlicensed facility in the central part of the state. Inspection of the facility revealed numerous problems, including rodents that were infected with the outbreak strain of Salmonella Typhimurium.

The authors of the 2005/06 outbreak investigation report had this to say:
This outbreak, along with the previously reported outbreak, demonstrate the need for more detailed oversight of the commercially distributed rodent industry. We recommend that states assess the feed rodent facilities in their states and require that proper infection control procedures be maintained. Efforts need to be made to educate rodent breeders and distributors about proper infection control and biosecurity practices, and to develop regulations of this industry that will facilitate control of zoonotic diseases in rodents. Public education regarding the risk of salmonellosis after handling rodents, especially in vulnerable populations at risk for severe complications, is another key component in preventing such outbreaks in the future.

Thoughtful recommendations, but was anybody listening? Obviously not MiceDirect or the company's home state of Georgia.

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  1. Several quick points, because oy this article is all over the place.
    -There's not 'a couple companies'. There is a huge market in frozen/thawed feed, and the majority of reptile owners use this method. It's safer for the animals, cleaner, and a painless euthanasia for the food.
    -the fact that this strain cannot be passed to your reptiles is HUGE, because reptiles can become carriers that will reinfect humans over and over, making it worse than simply a human-passed strain that's killed when you're done suffering from it.

    This could all be avoided if more people washed their hands.

  2. @Anonymous. I have not done a market survey to determine the number of companies. The more companies, the greater the potential hazard.

    I grant that this method of feeding has the benefits of painlessness and physical safety. But the company's assertion that this strain cannot be passed to reptiles is simply wrong. The British investigation of their outbreak - caused by the identical strain carried by mice supplied by MiceDirect - found the strain in at least a couple of the snakes that had been fed the frozen/thawed rodents and that were kept by people who, in turn, had become infected with the Salmonella.

    You are correct. The reptiles simply carried the Salmonella without showing any symptoms. The owners had no way of knowing that their snakes had been infected.

    Washing hands helps avoid spreading the infection, but it is not 100% effective. Nor can children who play with their pet reptiles (and many of the outbreak victims were children) be relied upon to wash their hands assiduously after each time they touch their pets.

    Companies that produce and sell pet foods (including frozen rodents) have a legal and moral obligation to ensure that these foods do not contain contaminants that may harm either people or their pets.


  3. @Phyllis

    I agree that the companies have a huge obligation to safety of people, and I think we're agreeing on that much. But salmonella is going to be with live rodents too, and many of these places also provide stock to petstores, labs and zoos.

    So getting to the base of the matter, it's the rodent suppliers and has little to nothing to do with the reptiles or their owners, beyond them being victims.

    (personally I'm just glad that I looked into hiring the company Disneyworld Animal Kingdom trusts)

  4. @Anonymous

    Yes, Salmonella definitely inhabits live rodents, and these have been the source of Salmonella infections in people, too.

    MiceDirect has taken the very sensible step of irradiating their frozen rodents, effective July 24th. Can't do that with the live ones, unfortunately!



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