Pet food/Salmonella outbreak
An article released today in the journal Pediatrics (Behravesh et al, 2010) provides more information about a salmonellosis outbreak linked to pet food. The outbreak itself is old news - I commented about it almost two years ago. What is new is the detailed epidemiological analysis of the outbreak, and there is some interesting information in the paper that is worth reporting. Here are the highlights:
Almost 50% of people who were infected were kids two years of age or younger.
- That's not too surprising considering kids less than five years of age are a high-risk group for getting sick after being exposed to Salmonella.
Households with sick people were almost 7 times as likely to have recently purchased the affected food.
- This provides good evidence of the link between the contaminated food and disease.
The Salmonella strain that was found in people was also found in bags of pet food at the manufacturing plant, samples from the manufacturing plant environment, and fecal samples from dogs that had eaten the food.
- This is pretty convincing evidence that the food was the source. Because they were able to type the Salmonella strain in people and it was an uncommon strain, and they then found the same uncommon strain in food, animals and people, it paints a pretty clear picture of what happened.
Illnesses occurred over a 3 year period.
- This is pretty concerning. This was more than a little lapse at a plant that led to contamination of a single batch of food or a short term event. This was a major failure in quality control that was undetected for a long period of time, resulting in at least 79 human infections in 21 US states.
A cluster of infections caused by the strain involved here, S. Schwarzengrund, was identified early in the outbreak. However, a link with pet food was not considered until the following year.
- That's unfortunate but maybe not surprising. There are a lot of other more likely sources of infection that were probably focused on initially. "What kind of pet food do you feed your dog?" was unlikely to be a routine question asked of people with infections. Identification of outbreaks caused by uncommon events is difficult and typically takes more time.
People that fed their dog in the kitchen were 4 times as likely to have an infection.
- Feeding a pet in the kitchen presumably increased the chance of cross-contamination with human food or contamination of the food preparation environment.
The cause of contamination was never identified. The authors of the paper suspected that contamination occurred after extrusion (the process during which the kibble is formed), which makes the most sense. The extrusion process results in high enough temperatures to kill bacteria like Salmonella. Possible causes of contamination include contaminated equipment used after extrusion, cross-contamination of pre- and post-extrusion food and contamination of substances (e.g. flavour enhancers) sprayed on kibble after extrusion. The fact that Salmonella was found in the room where materials were sprayed on the kibble supports this further.
In general, dry pet food is quite low-risk in terms of Salmonella contamination, but just like with other non-raw-animal products such as lettuce, tomatoes and sprouts, contamination can occur and human infections can result. The best way to reduce the risk is to use good general hygiene practices, particularly washing hands after handling food, keeping pet food and pet food bowls out of kitchens and limiting contact of young children and other high-risk individuals with pet foods.
Salmonella recalls: When to test
The recent run of Salmonella recalls in dry foods, raw foods and supplements has resulted in a lot of questions about when animals should be tested for Salmonella. In general, testing is only indicated in animals that have disease suggestive of salmonellosis. Diarrhea is the main issue, but other problems such as fever, decreased appetite and bloodstream infections can also occur. Clearly, any animal with signs such as these needs to be tested for Salmonella. However, there is no indication to test healthy dogs and cats that have been exposed to recalled products.
Why is that? An important concept in medicine is that you should always have a plan about what to do with the results of diagnostic tests - the result should have an impact on what you do. When you think about what would happen with a negative versus a positive test for Salmonella in a healthy pet, it shows why testing is not useful.
What would I tell you about a negative result?
- I'd say it means the animal is probably negative, but it could be a false negative because of intermittent shedding of Salmonella in stool or a false negative test result.
- I'd also say that even if there was no Salmonella, every animal is shedding multiple potentially harmful pathogens in its stool.
- So, I'd emphasize that if the animal became sick, Salmonella still needs to be considered and that good hygiene measures should be used around the animal (particularly its stool).
What would I say about a positive result?
- I'd say that means the animal was shedding Salmonella at the time the sample was collected, but that doesn't tell us if the animal is still shedding or how long it will do so.
- There's no indication to treat the animal. There is no evidence that treatment of dogs and cats that are shedding Salmonella is needed. There's also no evidence that it's effective. In fact, there are concerns that giving antibiotics could prolong shedding of Salmonella and that it could increase antibiotic resistance.
- Salmonella is certainly a public health concern, but there's not much specific to be done.
- So, I'd emphasize that if the animal became sick, that Salmonella still needs to be considered and that good hygiene measures should be used around the animal (particularly its stool).
Since my recommendations for a positive result and a negative result from a healthy animal would be the same, why test?
Expanded Iams recall
Following on the heels of a limited recall of feline dry renal diets because of potential contamination with Salmonella, Proctor and Gamble has now recalled all Iams Veterinary Dry Products, as well as Eukanuba Naturally Wild, Eukanuba Pure and Eukanuba Custom Care Sensitive Skin. These products are sold across the US and Canada, and all products with best-before dates between July 1, 2010 and Dec 1, 2010 (so, presumably everything that is on the market at the moment) are included. The broad scope of the recall is apparently a proactive measure based on the premise that since Salmonella was found in some products made at a particular production facility, there is the potential for contamination of everything made there. More data about what they have found and how widespread the contamination is would be nice (but is not forthcoming at the moment).
No illnesses have been reported. If your pet is being fed one of the recalled diets and develops diarrhea, vomiting or other signs of illness (e.g. weakness, fever, decreased appetite), it is important to consider the possibility of Salmonella. Similarly, if any people in the house develop these types of symptoms, they should make sure their physician knows they may have been exposed to Salmonella. Presumably, the level of contamination was low and the risks to the general public (human and canine/feline) are relatively low, with higher risks to people and animals with compromised immune systems or other diseases that limit their ability to fight off a bug like Salmonella.
Frozen mice recall: Salmonella
MiceDirect, a company that sells frozen mice, rats and chicks as reptile feed, has issued a recall because of Salmonella contamination of their product. Contaminated critters have been sold across the US (except Hawaii) through mail order and pet stores, and recalled product codes can be found in the FDA recall notice. Contamination isn't a big deal for the reptiles, since carriage rates for Salmonella are already high and they are usually healthy carriers. The concern is for people who handle the frozen rodents/chicks (or who can be exposed indirectly from contaminated surfaces in the home). There have been previous outbreaks of human Salmonella infections associated with contaminated frozen rodents.
Unlike many other recalls where the product is recalled because of contamination but without evidence of human illness, human illnesses suspected to be linked to contaminated reptile food have been identified in 17 states. In reality, reported cases may be the tip of the iceberg, and I suspect that if cases in 17 states are confirmed, there will be (or may already be) many more. Other details regarding these cases and the recall, such as the strain of Salmonella involved, haven't been released.
In response to this problem, the FDA report and the company website indicate that products from MiceDirect will be irradiated. It's not clear if this will be a standard protocol from now on, or whether it's a short-term response to the contamination problem. Considering the repeated outbreaks associated with frozen reptile food, irradiation sounds like a good standard practice. Perhaps the best way to help make (or keep) it a standard practice industry-wide is for consumers to vote with their wallets: ask for irradiated or otherwise treated (e.g. high pressure pasteurization (although I'm not sure what that would do to a mouse)) feeds to reduce the risks of contamination.
Because of recurrent problems with contaminated frozen reptile feed, if people are not buying products that are treated to eliminate contamination, they should assume that all such feed is contaminated and handle it accordingly. That means using basic practices such as:
- keeping frozen reptile feed away from human food
- if defrosting it in the refrigerator, keep the reptile feed in a sealed container that is not used for human food and that is disinfected afterward
- washing hands after handling the feed
- disinfecting any potentially contaminated surfaces that come in contact with the feed
- discarding uneaten food promptly, since Salmonella can multiply as uneaten food sits in the open, especially in a nice, warm reptile terrarium
A link to more information about MiceDirect is available through a post on Barfblog.
Iams recall: Salmonella
Proctor and Gamble has announced a recall of two lots of Iams' Veterinary Formulas Feline Renal, a prescription dry cat food. The lot numbers are 01384174B4 and 01384174B2. Anyone that has this food should stop using it immediately. Since these are prescription diets that should only be available through a veterinarian, affected customers should presumably contact their veterinarian for information about a replacement or refund. If a cat that has eaten this food develops diarrhea, Salmonella should be considered as a possible cause and a stool sample should be tested.
As with most of these recalls, no illnesses have been reported, although lack of reported cases doesn't necessarily mean lack of cases. While Salmonella contamination of dry pet food diets is quite uncommon, it can happen. It's a good reason for people to make sure they wash their hands after having contact with any pet food or the pet's food bowl, and to make sure that pet food is kept separate from food meant for human consumption.
Salmonella recalls
A couple of more Salmonella recalls have occurred recently. Feline's Pride Natural Chicken Formula, a raw chicken diet, has been recalled, as has Natural Balance Sweet Potato and Chicken, a kibble diet.
Finding Salmonella in commercial raw diets is expected and I'm surprised about the recalls that have happened. If you buy raw meat, you need to assume that it's contaminated with Salmonella and various other potential pathogens. Salmonella in kibble diets is more surprising, and is a concern because people do not tend to handle kibble as potentially contaminated.
These recalls highlight a few points to me:
- Always assume you have Salmonella and other nasties in raw meat. Careful attention to handling of raw meat and personal hygiene (e.g. handwashing) is critical.
- While lower risk, kibble is not innocuous, so wash your hands and prevent cross-contamination of kibble with human foods.
- "Natural," along with "organic," "super premium" and other marketing catch-words tell you nothing about the quality and safety of a product. There's no evidence that any products marketed as organic, natural, or anything else along that line are at all superior to diets produced by reputable companies, particularly diets that have undergone proper development and testing, including AAFCO feeding trials.
Salmonella recall: Pet vitamins
All lots of "Pro-Pet Adult Daily Vitamins" have been recalled by United Pet Group, Inc. because of Salmonella contamination. At least one lot has tested positive for Salmonella, although there is no mention about whether the bacterium was detected during routine testing or in response to a problem. Regardless, Salmonella contamination of these products is a concern because of the potential for disease in dogs fed the vitamins. Further, people could become infected from contact with dogs that become infected from the vitamins, or from handling the vitamins directly. If you have these vitamins, stop using them immediately. If your pet has been receiving these vitamins and develops fever, diarrhea, anorexia or any other signs of illness, take your pet to your veterinarian and make sure he/she knows there has been a chance of Salmonella exposure.
Raw food recall expanded
Nature's Variety has expanded their recall based on more concerns about Salmonella contamination of their products. In a lot of ways, this makes no sense to me since you have to assume that raw meat is contaminated with Salmonella, E. coli, Campylobacter and various other pathogens. That's been clearly shown in studies of raw meat for humans and animals, and that's why we cook meat intended for human consumption and emphasize good food handling practices. It's also why there are concerns about feeding raw meat to pets, and the explanation for various studies showing pets fed raw meat have much higher rates of shedding potentially harmful bacteria like Salmonella. You have to assume that a reasonable percentage of Nature's Variety's food has been contaminated with Salmonella, not that this is an uncommon and preventable event.
Because of the problem or consumer concerns, Nature's Variety has announced that they will be treating all of their diets using high pressure pasteurization. Basically, this process uses very high pressures (with only a slight increase in temperature) to reduce bacterial levels. I can't find any scientific literature about the effectiveness of this method on Salmonella contamination of raw meat (it's mainly used with milk and cheese) but it should be able to greatly reduce bacterial levels in meat. That's a good thing, as long as it works. What's important to know, however, is whether it is really highly effective in this situation and whether all potentially harmful bacterial will be eliminated every time.
I'm concerned that if people think this food is "sterile" and it's not, they might not take the necessary food handling precautions. If this method usually, but not always, kills all of the bad bacteria, or if it reduces levels greatly but not completely, then there could still be the risk of infection of people and pets. This information is critical. In the absence of clear scientific data, I think we need to assume that some level of contamination could still be present (although probably much less often and at a much lower level), and make sure that proper food handling practices are used.
It's good to see this company taking measures to reduce the risks associated with raw meat feeding. Let's hope that some objective research is made available to indicate what risks might remain.
Image source: www.defendingfoodsafety.com
Raw food recall: Salmonella
Nature's Variety has recalled chicken-based raw meat products because of Salmonella contamination. After a customer complaint about "digestive problems," they tested the food and found Salmonella, prompting the recall. (For more details about the recall, click here.) In some ways, this doesn't make a lot of sense to me. If you think Salmonella contamination should be an uncommon event and a problem, you should test routinely, not wait until animals get sick. If you think that Salmonella contamination of raw meat is expected (which it is), then why test or recall? Just assume that every raw meat sample is positive for Salmonella (and Campylobacter, and E. coli). Recalling raw meat for Salmonella isn't logical. Presumably, a large percentage of the raw meat that they have sold and which they will sell in the future is contaminated, based on various studies of commercial raw meat. Handling and feeding raw meat carries an inherent risk of human and animal infections with Salmonella, Campylobacter, E. coli and other bacteria. People that feed raw meat need to understand that risk, and consider whether it's a reasonable risk for their pets and the people in the household. I don't think feeding raw meat is a good idea, but in some situations it's a particularly bad idea (e.g. when there are infants, elderly persons or immunocompromised people in the household, when the pet is very old or very young, when the pet visits high risk people).
More information about raw meat feeding can be found on the Worms & Germs Resources page.
Listeriosis in a dog from recalled meat?
A Windsor, Ontario woman is convinced that her dog acquired listeriosis afetr eating recalled hot dogs. Last week, Maple Leaf Foods recalled various hot dog products because of low-level contamination with the bacterium Listeria monocytogenes, the cause of listeriosis. Her dog Tigger was fed four hot dogs one evening, and the next morning starting vomiting. He recovered after a few days of treatment. No specific testing was done to investigate the possibility of listeriosis.
Dogs can get listeriosis. Non-specific signs of infection including vomiting, diarrhea and fever are most common. Neurological disease can occur in a small percentage of cases. Listeriosis is extremely rare in dogs, however, despite the fact that dogs are certainly exposed to the bacterium periodically. Just because the dog ate recalled meat and got sick, it does not mean that the dog had listeriosis.
No human illnesses have been reported in association with this recall, and it's very unlikely that this dog actually had listeriosis. It's possible but I really doubt it. Dogs get gastrointestinal disease like this all of the time, from a variety of causes. Eating four hot dogs in one night could itself cause diarrhea in some dogs.
Some tips come to mind from this story:
- Limit feeding of treats to dogs. Four hot dogs is pretty excessive. Low fat, nutritious treats are better.
- Pay attention to recalls. Don't eat recalled food or feed it to your pet. At the same time, don't overreact to recalls. We are exposed to potentially infectious agents on a daily basis, but a combination of our immune system, normal bacterial populations in the intestinal tract, low levels of contamination and other factors mean that we don't usually get sick. If you are concerned about listeriosis, make sure processed meats are cooked before feeding.
- If you are really concerned or suspicious about a disease, make sure testing is done.
- If you think food is the source of a problem, save a sample. It might be useful to test the food.
More information about listeriosis in animals is available in the Worms & Germs archives.
Bird seed recall: Salmonella
As you undoubtedly know, a large Salmonella outbreak has occurred in the US, associated with contaminated peanuts. The scope of this outbreak continues to expand in unexpected areas, including pets. The latest development is a voluntary recall of bird seed. The recall affects 20-pound packages of Wild Birds Unlimited Wildlife Blend bird food (produced by Kentucky-based Burkmann Feeds) with the manufacturing date code 81132200 2916 08124.
The contaminated bird seed was linked to the deaths of several birds in North Carolina, and it was confirmed that the bird seed manufacturer received peanuts from the Georgia facility that was implicated in the Salmonella outbreak.
People that have used this bird seed should clear out their bird feeders, ideally while wearing gloves. The feeders should be thoroughly cleaned and then disinfected (although this may be easier said than done). Hands should be washed after handling the bird seed, potentially contaminated feeders or any other potentially contaminated items.
The risk to people is presumably quite low, but people handling the bird seed could potentially contaminate their hands with Salmonella and then inadvertently swallow some of the bacteria. Concerns are greatest in people with compromised immune systems, the very young, the elderly and people taking antibiotics, as they are more likely to get sick following exposure to small numbers of Salmonella.
More information about Salmonella can be found on the Worms & Germs Resources page.
Dog infection linked to peanut butter Salmonella outbreak
Maybe the only thing surprising about this is that it's taken this long, but there has now been a dog infection reported in association with the massive peanut butter recall due to Salmonella contamination. This outbreak has made hundreds of people sick, and caused a few deaths so far. Pets that eat contaminated "people food" or pet treats are also at risk. So, it's not too surprising that an infection in a pet has now been reported (and reported cases are usually just the tip of the iceberg).
The case reported involves a dog in Oregon that was diagnosed with salmonellosis after being fed Happy Tails dog biscuits. The Salmonella strain recovered from the dog, who had severe diarrhea, was from the same serogroup as the strain involved in the peanut product outbreak. The product (Happy Tails Multi-Flavor dog biscuits, UPC 41163 42403, 4 lb box, “best by” date Oct 31 09) was tested at IEH Laboratories & Consulting Group in Lake Forest Park, WA and Salmonella was identified. Other products from this and several other companies have been recalled, so pet owners should check the products against recall lists. If in doubt, do not feed your pet(s) any treats until their safety can be verified.
Salmonella can cause disease in dogs ranging from mild diarrhea to severe bloody diarrhea and bloodstream infection that can be fatal in some cases. Dogs with salmonellosis can also transmit the infection to people, because they can shed large numbers of Salmonella in their stool.
If pets have been fed potentially contaminated peanut butter or treats, they should be watched carefully for signs of diarrhea, lack of appetite or decreased activity, and taken to a veterinarian promptly if there are any concerns. There is no indication to test or treat healthy pets that have potentially been exposed. Even if stool samples were tested and Salmonella was found, treatment of healthy animals would not be recommended. As always, careful handling of stool and frequent handwashing are key factors for preventing transmission of disease to people.
Peanut butter recall now affects pet products
I'm sure you've heard about the large outbreak of salmonellosis in people in the US associated (again!) with contaminated peanut butter. Based on the extent of the outbreak, it probably should not come as a surprise that pet treats are now caught up in the recall. The FDA has announced that the recall now includes some pet food products that contain peanut paste produced by the Peanut Corporation of America (PCA) at its Blakely, Georgia processing plant. The concerns here are two-fold: the risk of disease in pets fed the treats, and risk to people handling the treats. If you have peanut butter-containing pet treats, you should stop feeding them to your pet(s) until you can determine whether or not they are affected by the recall.
The recommendation in the recall notice really applies at all times: "It is important for people to wash their hands--and make sure children wash their hands--before and, especially, after feeding treats to pets."
More information on Salmonella and pets can be found on the Womrs&Germs Resources page.
