A Montreal pediatrics resident has expressed concern about rat bite fever in kids.
Dr. Karine Khatchadourian described three cases of this bacterial infection in a paper called “The rise of the rats: a growing paediatric issue,” published last year in the journal Paediatrics and Child Health. The article didn’t really present any evidence that this is a “growing” issue, but it is a disease of concern.

Rat bite fever is a bacterial infection most commonly (but not exclusively) associated with bites from rats. Healthy rats often carry the bacterium that causes the disease (Streptobacillis moniliformis in North America), and infection can occur when the bacterium is inoculated into the body by a bite, or when it’s spread to mucous membranes like the mouth through direct mouth-mouth contact with pet rats (yes, some people kiss their rats).

The disease can be serious, and even fatal, if not properly diagnosed and treated. It’s also a classic example of why physicians need to ask their patients about pet contact and why people need to take bites from pets seriously. Knowing that a rat is in the house, and particularly if a bite has occurred, is a key factor in helping make the diagnosis. If the physician doesn’t ask the question, this critical piece of information may be missed, along with the diagnosis.

Being concerned about rat bite fever (and other zoonoses) is good, and ways to educate pet owners and physicians about such diseases are needed. However, extrapolating “rat bite fever is bad” to “rats are bad” is a stretch. The statement in the paper Should we, as health care professionals, advocate to have rats banned from being sold in pets stores?” is over the top.

Every animal carries many microorganisms that can cause disease in people, given the right circumstances. Similarly, every person you meet is carrying something infectious. The key things to consider are:

  • What is the likelihood of infection?
  • How severe is the disease that may occur?
  • What can be done to reduce the risk of infection?
  • What is the cost-benefit, i.e. how do the potential risks compare to the potential benefits?

How can the risks be reduced?

  • Rat owners need to be aware of the disease.
  • Good handling practices are needed to reduce the risk of bites.
  • Any bites that occur should be promptly cleaned and a physician contacted if there are concerns.
  • Contact of rat saliva with broken skin or mucous membranes (e.g. kissing the rat) should be avoided.
  • Physicians need to know whether their patients own pets, including rats, and know what diseases may be associated with those types of animals.

With this type of approach, the risk of infection can be reduced and the ability to properly and promptly diagnose the disease, in the odd case that it occurs, can be maximized.

I don’t want to downplay rat bite fever. It certainly can cause illness, particularly in children under the age of 12.  A recent paper reported a fatal case in a 14-month-old boy, however in that case the infection was associated with ferrets, not a rat.

Parents of small children need to think about the risks of zoonotic diseases, as well as injuries (e.g. bites) when deciding whether to get a pet, and what type of pet to get. If people like rats, take care of them properly and communicate well with their physician (and if their physician is aware of the issues), then the risks of serious disease are quite low.

Dr. Khatchadourian suggests that parents “should stick to cats and dogs, and steer clear of rats.” However, that’s no assurance that a zoonotic infection will not occur. There’s no evidence indicating the risk of disease is less with those species. It doesn’t even eliminate the risk of rat bite fever, since Streptobacillus moniliformis can be found in the mouths of dogs too.

Rather than banning rats from pet stores, we should focus on educating pet owners, veterinarians and physicians about zoonotic diseases.


  • Jordan

    There are millions of bacteria surrounding you 24/7. The key is good hygiene, making sure your rat is socialized properly and doesn’t have an immature abusive child pestering it, and they are no more likely to bite than the nicest of dogs. In any case that you get a scrape/cut/bite from an animal or really anything it is best to wash the wound and sterilize it. I have owned rats since I was 8 years old (26 now). I have been bit on several occasions by new rats that were not socialized yet, and never once had an adverse reaction other than pain. Rats are great pets, and they keep themselves extremely clean in a clean environment. Take care of your rat, keep their cage and toys clean, hold/talk to/ play with your rat, and you should have no fear of them biting you. And if they happen to, just go wash it off and put some Bactine on it. I must stress though, children who are not mature enough to handle the responsibility of having a small animal SHOULDN’T!

  • syd

    I agree with Jordan. Just remember hygiene and you should be all right. Ive been bitten by a rat at the pet store and nothing happened!

  • Zoonia

    Rats are extremely clean. Like any animal, it can “actually” may be carrying barctéries, diseases, germs (Although More often it is more problematic for their health and for ours! “Cancer, tumors, insufisance any kind, genetic defects due to inbreeding “…

    I manipulate the rat “domestic” since the age of 12 years (28 years today). I’ve never had any illness caused by my pet. That said, as you say in your article, it is the responcabilité owner to properly maintain their animals. I think anyway that any animal should not aproach a young child! This is more of a problem of society and education than cleanliness or animal disease …

  • Meaghan Edwards

    I had rats ever since I was eight years old. I wonder how I survived . . .

  • Kz

    Ridiculous. I’ve been kissing rats on the mouth for many years and I’m miraculously still alive. The only reason kids shouldn’t have rats is the risk of them injuring the RAT.