Every couple of months there’s a news report about a person with infection caused by the dog-associated bacterium Capnocytophaga canimorsus. Most of these reports don’t get too much attention, but every once in a while they get picked up pretty widely, resulting in another round of questions about this strange bacterium. It’s a bit of an oddball bug that can be found in the mouths of most healthy dogs. It doesn’t often cause disease in people, but when it does, it’s usually severe and is often fatal. One reason we don’t see much disease, despite the commonness of the bacterium, is that it tends to only sicken certain types of people, particularly those who don’t have a spleen.

While it’s a rare cause of illness, it happens more often than the news reports.  I hear about additional cases from people who have been infected themselves or have affected family members. Some common themes tend to come up, which can be frustrating because they’re issues we’ve been talking about for a while.

Here are a few of the comments that are commonly heard:

I’ve never heard of this bug before.

That’s not really surprising since it is a rare cause of disease, and not one most people would be expected to have heard about.

My doctor didn’t seem to know anything about it. Neither did my vet.

Again, not too surprising. It’s not something most MDs or veterinarians see regularly (or ever) in practice. Medicine and veterinary curricula are already packed, so rare things like this don’t get much, or any, attention. I’ve talked to physicians and most say they haven’t heard of it. I talk to veterinarians about Capno regularly as part of zoonotic disease talks, and only occasionally does someone know about it.

I’m missing my spleen and I didn’t know this was a concern.

That’s a problem. People who lose their spleen (or have a spleen that doesn’t work) have lost one of their immune organs. That makes them more susceptible to certain infections, such as this one. They need to know that, and what it means to them (e.g. if you are bitten by a dog, you need antibiotics, regardless of the location or severity of the bite).

No one at the hospital knew I was missing my spleen.

Unless (until, hopefully) we have a universal medical record system that takes your health info with you, things like this get missed. Someone who’s undergoing chemotherapy and is immunocompromised is highly aware of their immunocompromised status, and is motivated to tell their healthcare providers and it might be more obvious to the healthcare team. Someone who lost their spleen years ago may have no outward signs and may not think about it (especially if they haven’t been adequately informed about the risks). Sometimes (often, perhaps) that big risk factor isn’t identified in Capno cases until very late in disease, after it’s diagnosed. (e.g. Dr: “This is a disease that occurs most often in people that have lost their spleen.” Response: “Oh, he lost his spleen in a car accident years ago.”)

No one asked about animal contact.

This is a major area of concern and one on which we’re not making a ton of progress. I get involved with lots of cases of various types of infections each year where the simple “do you have animals?” or “have you had contact with animals?” question would have likely lead to a quicker diagnosis. Sometimes, like with Capno, quicker might be the difference between eventual recovery vs lifelong consequences vs death. It’s an easy question but it’s not asked often enough.

I didn’t think to mention the bite (or other exposure, such as a lick over broken skin).

This is another weak link. If no one asks, people need to know to offer the information and to make sure someone’s paying attention to it. Too often, no one mentions it because it was a minor bite, and that can sometimes mean the difference between life and death.

Fortunately, infections from this bacterium are rare. Unfortunately, when they occur they are usually very bad. They’re also highly preventable with some basic understanding of who’s at increased risk and what to do. Like a lot of things, a little communication goes a long way.

More information about Capnocytophaga is available on the Worms & Germs Resources – Pets page.