Feline Zoonosis (part two): Only Rock n Roll?

As you learned in our last piece, toxoplasmosis has been burdened with an ominous reputation which sometimes led physicians to recommend eviction for the pet cats of pregnant women. In reality, toxoplasmosis is pretty hard to get from a pet cat. On the other hand, contracting cat scratch fever is a cinch. The CDC has estimated that 12,000 Americans get it every year, and 500 of those end up in the hospital.

Wait, cat scratch fever, you say? But that’s not a real thing. It’s only rock and roll. True, “Cat Scratch Fever” is the title of a song by Ted Nugent, who is neither a doctor nor an especially reliable source of information about infectious disease. It is, however, a real thing.

For clarity, this usually goes by the name cat scratch disease. Human beings catch it from normal play behavior with a healthy pet cat. A shallow scratch from tooth or claw is the usual means of delivery. It is extremely common for cats to carry this organism around for long periods of time, because it has little to no effect on them. Not so harmless inside a human, though. Bartonella, the disease-causing agent, enters at the site of a minor scratch, creating a tiny abscess, then fever with tenderness and enlargement of the nearby lymph nodes. For example, a small wound on your hand might result in a large, firm, painful swelling at your armpit. Many people recover (after weeks to months of discomfort) without permanent consequences, but this infection can be extremely serious, even fatal, for someone with a compromised immune system.

It’s challenging for cat scratch disease to make the jump from pet to human without any assistance from a flea. Fleas can go unnoticed because their bite seems to be less irritating for cats than for dogs; thus, scratching and hair loss may be subtle. Furthermore, most cats don’t have any naturally occurring bald spots (like the undercarriage of a dog) where fleas can be easily observed going about their business. This parasite spends all of its time extracting blood from the skin and digesting it, periodically defecating wherever it happens to be standing. The end result is a nearly infinite supply of concentrated Bartonella pellets, widely distributed over the surface of the host and ready to contaminate any minor skin abrasion you receive when playing with your pet. Eliminate fleas from this environment, and the chain is broken. Many products and strategies are available to eradicate them from your home.

Many people with subpar immune systems really want to own pets. If this bacteria is so common in healthy animals, is it safe for an elderly person or chemo patient to have a cat? The CDC does advise immunocompromised people to avoid kittens less than a year old, but the true villain here is the flea. Team up with your vet for this, because a top-tier parasite prevention strategy is vital in maintaining the important bond between high-risk owner and feline companion. 

Dr. M.S. Regan