The CDC is investigating CDC is investigating more cases of salmonellosis associated with feeder rodent contact, caused by the less-than-catchy-named Salmonella I 4,,12:i:-. This strain is the same one that was implicated in a large and prolonged outbreak in the US and UK in 2009-2010 which was also associated with frozen feeder rodents (rodents sold frozen as reptile food) from a single US supplier. The current outbreak has affected people in 22 US states from August 2011-February 2012, and involvement of the same strain from the same source certainly leads to suspicion that this is actually an ongoing problem.
In the latest outbreak:
- 46 people have become sick. As is common, kids have borne the brunt of this outbreak, with the median age of affected persons being 11 years.
- 37% of affected people were kids five years of age or younger. Since this outbreak involved feeder rodents, clearly people aren’t heeding the guidelines that kids of that age shouldn’t be in households with reptiles.
- No two affected people reported buying rodents from the same store. This shows how widespread the problem is and that it must be originating from the place where the rodents are bred and/or distributed, not a focal pet store issue.
Record-keeping at the pet stores complicated figuring out the source. However, two breeders that supplied pet stores received mice from the company that was the source of the 2009-2010 outbreak. This suggests that not only were people exposed from frozen feeder rodents in the earlier outbreak, but that breeding colonies in different areas were infected from that source. This may have allowed wide dissemination of this Salmonella strain into numerous rodent breeding colonies, creating many possible sources of exposure for members of the public purchasing feeder rodents. The large-scale commercial nature of rodent breeding and wide distribution network creates a great opportunity for widespread outbreaks, as is apparent here and with various other outbreaks (including salmonellosis outbreaks from guinea pigs and baby poultry).
If you are going to buy feeder rodents:
- Treat them as if they are carrying Salmonella, because they just might be.
- Keep them away from human food. Keep them in a separate freezer or fridge, or in a sealed container if they have to be in the same fridge as human food.
- Don't handle them in the kitchen.
- Wash your hands thoroughly after handling.
- Keep them away from young children, as well as people with compromised immune systems, elderly individuals and pregnant women. None of these groups should have contact with reptiles either.
Image: A package of frozen rats, as sold commercially for feeding reptiles.