The headline’s true, but a bit sensational. However, it’s from a recent paper that has attacked a lot of attention (Being Licked by a Dog Can Be Fatal: Capnocytophaga canimorsus Sepsis with Purpura Fulminans in an Immunocompetent Man, Mader et al 2019).
This recent fatal Capnocytophaga canimorsus infection in a German man has gotten a lot of attention. It’s a bit of an obscure bacterium (despite being present in the mouths of pretty much all dogs) and one that I disproportionately talk about because it’s not well known. Most veterinary audiences don’t have much background on it (reasonably, since it doesn’t typically cause disease in animals), but it’s an important thing to know when talking to dog owners about risks from bites. When I talk to physicians, there’s usually a similar lack of recognition.
While this bug is common in dogs, human infections are rare. They usually occur in people without a functional spleen or in people that have compromised immune systems. In those individuals, a bite or other type of contact of dog saliva with wounds or mucous membranes (mouth, nose, eyes) creates the potential for disease, and is an indication for prophylactic antibiotics.
However, in the general population, infections are exceptionally rare.
The case report describes a fatal infection in a 63 year old man who was otherwise healthy and had no known immunocompromise.
- That’s really rare.
He had a dog and had not been bitten, but had been licked.
- That’s rare too but happens.
He developed severely progressive disease and ultimately died after 16 days of aggressive care.
- Unfortunately, that’s not rare. A large percentage of infected people die, and those that survive often have devastating complications.
The authors drew a couple conclusions
Pet owners with flu-like symptoms should urgently seek medical advice when their symptoms exceed those of a simple viral infection, which in this case were severe dyspnoea and petechiae. Physicians confronted with such patients should ask about contact with dogs and cats.
- I’d expand that to contact with any animal, since this bacterium is not the only issue. Further, everyone plays a role here. Patients or their families should report animal contact if their healthcare provider doesn’t ask.
They [healthcare providers] should consider C. canimorsus infections also in the presence of purpura fulminans and the absence of animal bites or scratches, and any immunodeficiency. In such cases, the clinician should immediately start empiric treatment with a penicillin in combination with a beta-lactam inhibitor until a definite diagnosis is established.
- It’s hard to say that Capno should be considered in every person. I guess it’s fine to say ‘think about it’, but common things occur commonly, and this infection in a healthy person isn’t one of them. Early recognition is important and fortunately, someone coming with this severe of an infection would be expected to be started on an antibiotic that would also kill Capno (since it’s susceptible to a range of antibiotics).
For me, the key is preventing it from getting to this stage. That doesn’t apply to an odd case like this, but to the majority of cases, where there’s a known (but not necessarily recognized) risk factor, lack of recognition of the potential problems from a dog bite and frequent lack of communication about animal exposure and bites. Failure to realize the risk in a typical high risk person contributes to many deaths.
More information about Capnocytophaga canimorsus can be found in the fact sheet in our Resources section.