The CDC has released the findings of an investigation of a prolonged multistate outbreak of salmonellosis that was linked to dry dog food in 2006-2007. This outbreak implicated two different dog food brands, both made by the same manufacturer in the same plant in Pennsylvania, as the source of a particular strain of Salmonella Schwarzengrund. The strain infected numerous people, and was also found in some dry dog food samples and stool samples of dogs that were fed the food, with which the affected people had had contact. No illness was reported in the pets. It is unclear whether people were infected from contact with the food or contact with the pets’ stool.
This is the first report of salmonellosis associated with dry pet food. Previous outbreaks have been associated with contact with raw pet treats such as pig’s ears. Overall, the risk from contact with dry pet food is quite low, although this outbreak clearly demonstrates that some risk exists. Handwashing after contact with pet food should greatly reduce the already low risk.
This report is certainly not a reason not to feed your dog or cat a commercial pet food. One concern that I have is that this report will (and already seems to) be used by proponents of raw meat diets as support for this feeding practice. Feeding of raw meat has been clearly shown to increase the rates of shedding of potentially dangerous bacteria such as Salmonella. Illness and death from these bacteria have been identified in dogs fed raw meat. The high rates of Salmonella shedding in raw-fed dogs are a significant public health concern, and these concerns have been previously reviewed. Outbreaks of human salmonellosis have not been reported in association with raw meat feeding. This could indicate minimal risk, but could equally be due to lack of identification of sporadic cases that would be more likely with raw food than large-batch commercial contamination or better hand hygiene practices associated with raw meat handling.
– The risk of Salmonella exposure is still much lower with good quality commercial pet food compared to raw meat.
– Wash your hands after handling pet food (of any variety), as well as food and water bowls.
– Care should be taken when handling animal stool to avoid any direct contact with it. Wash your hands after picking/cleaning up any type of stool, even if you use a plastic bag or a designated scoop to do so.