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Friday, February 28, 2014

What to Make of Rat Bite Fever

Rat Bite Fever has been all over the news lately due to the very tragic death of a 10-year-old boy in California who contracted the disease and died from it last summer.

This is the story: Family Blames Petco for 10-Year-Old's Death.

I am sure this story is giving people everywhere pause about keeping rats as pets. But before you pass any judgment on the suitability of rats as pets, keep a few facts in mind.

The bacteria in question,  Streptobacillus moniliformis, is very common in rats, but disease from it is extremely rare. It is more common in wild rats (colonization rate between 50% and 90%), but is also present in domesticated rats - both lab rats and pet rats (colonization rate between 10% and 90% - I know, not a very helpful range there). This is one of those bacteria that animals can harbor without actually contracting a disease from it.

Rats are not the only animals that carry this bacteria. Ferrets, weasels, mice, gerbils, guinea pigs, and squirrels all carry the bacteria, among others. Cats and dogs can also carry the bacteria, likely contracting it if they catch a wild squirrel or mouse or rat.

While the bacteria itself is pretty common, disease from the bacteria is extremely rare. In the US, there have only been 200 cases of Rat Bite Fever reported since 2004. The CDC does not even consider Rat Bite Fever to be a reportable disease. That 200 cases is likely underrepresented, because in the vast majority of cases (about 90%), it will clear up without treatment. Most people just assume they had the flu. In the remaining 10%, it can be easily treated with penicillin. Tetracyclines and some other antibiotics are also effective. It is very unlikely to be fatal if treated. It is most likely to require treatment in young children.

Prevention is simple. If you are bitten (and rats are far less likely to bite than other small animals), wash the wound and disinfect. Should you develop flu-like symptoms after having been bitten (the bite can happen as many as 2-4 weeks before symptoms) be sure to alert your doctor to the bite. If you develop flu-like symptoms that worsen or do not resolve quickly, be sure to alert your doctor that you have rats. It is always good to practice good hygiene and wash your hands after handling your rats or cleaning the cage. Most cases of Rat Bite Fever happen after a bite, but supposedly, it is possible to contract it without being bitten.

Also remember, if you do research into this, that some articles have made the claim that 10% of rat bites will result in infection with Rat Bite Fever. Debbie Ducommun looked into this further and discovered that this statistic was taken out of context from a study of wild rat bites in a 2-mile urban area, where cases of Rat Bite Fever were being reported. It is by no means representative of the pet rat population.

The Philly Rat Rescue reported on their Facebook page that a 7-day course of doxycycline will ensure your rats do not carry the bacteria. That post was later changed to say "proper course of antibiotic treatment" and suggest that if you have ever treated your rats with antibiotics, they are likely free of the bacteria anyway (the original wording is still in one of the comments of the post). If you are still concerned about your existing rats, you can certainly check with your vet about using antibiotics preventatively.

The news story that has triggered all of the attention has drawn comment by some rat fanciers that the facts do not add up. The way some stories read is that the boy was fine and then 24 hours later, severely ill and died. That description does not coincide with how we know Rat Bite Fever presents. It could be that there were other medical factors at play. It could be that the media has their facts wrong or do not have all of the facts. It could be that symptoms were missed earlier on. It could just be that this was some very rare severe presentation of the disease. I do not know. I do know that the way this case is being reported would be an extremely rare way for an already extremely rare disease to present.

From the reports, it appears that while the boy was taken to a pediatrician the day before, he was not treated for Rat Bite Fever. Being aware of this disease is essential. Likely, the child was not treated because the physician was not told that he had rats.

If you are still concerned about Rat Bite Fever, also keep this in mind:
  • If you feel that rats are not safe to keep as pets, remember that neither are gerbils, guinea pigs, mice, ferrets, cats, and dogs, because they all can carry the same bacteria.
  • Almost all types of animals can carry some type of disease that can be fatal to humans in very rare circumstances. For example, cats can carry Cat Scratch Disease and birds can carry Psittacosis. They are diseases that owners should be aware of, but not something that we should live in fear of.
  • The list of zoonoses (diseases that can be passed from animals to humans) is much longer for cats and dogs than it is for rats. There are actually very few diseases overall that can be spread from rats. You can check and see what diseases can be spread from your various pets to you on the CDC website: Note that Rat Bite Fever is not even listed here because the CDC does not consider it needing reporting. Only two diseases are listed, one being salmonella, which can be spread from any type of animal.
There are risks everywhere. You are far more likely to die in your car than from any illness you acquire from your pet, and yet we still get into cars every day. We take precautions - we drive safely and we fasten our seatbelts and put our children in safety seats. Likewise, we take precautions with our pets, by being knowledgeable about the illnesses they can spread and by practicing good hygiene. But there is no need to panic and abandon them altogether.

This case being reported is tragic and I feel for the boy's family. Just because something is very rare, doesn't mean that it cannot happen, and that is why we need to be informed - so we can make sure proper treatment is received if something terrible does happen. At least this news story is helping people to be informed about this disease. Unfortunately, it is also spreading uninformed fear and panic among some people and also painting a negative picture of pet rats in the eyes of many uninformed Americans. I want to help put this information in context.

Finally, there is always the question of whether Petco is at fault here. I honestly don't see it unless there is some type of negligence - some awareness on their part that this rat was a potential danger. But many rats carry this bacteria and will never spread disease. It is true that pet store rats are more at risk for this problem, as they come from mills. At the mills, the rats are stored in overcrowded bins in warehouses and warehouses are notorious for also housing wild rats. Exposure to wild rats will always increase risk. It is no secret that I do not support the mill industry and strongly support the rescue community. But still, I don't see this as being Petco's fault, unless further information is disclosed that they were aware or should have been aware that something out of the ordinary was wrong with this particular rat. The family claims they want to make things safer for others, but I am not sure that that is possible. The bacteria is very common, the disease is very rare. Unless the rat they bought was suffering illness from the bacteria and not just carrying it, it is probably no different than thousands of other rats in the pet industry.


  1. I had pet rats for years, and fostered babies for a rescue. The key is cleanliness. Of all of the rats I had, only one had been treated with antibiotics for an upper respiratory infection. I had young children while I had rats. My first rat was adopted from a litter produced from a "found" domestic rat that was pregnant. We have always gone into pet parenting with the mind that animal have bacteria, especially when cleaning up after them or handling them. SOAP. I washed my dogs, I washed my rats, I washed my hands and demanded that my children wash theirs, before and after handling any and all pets and their droppings, cages, pooper scooping. I've been scratched and bitten by rats..not maliciously, but nonetheless. I immediately washed with very warm water and soap for several seconds, then made a mental note to keep an eye on it. I didn't even know there was this disease until I read the story..but common sense says to keep any injury caused by an animal as clean as possible. It's a very sad story..I don't condone Petsmart selling rats, but I wouldn't claim them as a culprit in housing diseased rats either. Thanks for this article. Education and Soap are both preventives.

  2. You article says "200 cases since 2004" Everything I have read says 200 cases since 1839