The song "Cat Scratch Fever" may be playful in nature, but the disease is no laughing matter (and neither are the fleas that spread it).
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cat scratching and biting woman's hand
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Cat scratch fever is a bacterial infection that humans can get when a seemingly healthy kitty scratches or bites them (or licks an open wound). The condition is pretty rare in humans with only about 12,000 people being diagnosed with cat scratch fever each year—compared to 40 percent of cats that carry, or have carried, the bacteria.

Unlucky for me, I was one of those 12,000 people. Lucky for you, I've teamed up with a panel of experts for a first-hand scoop on cat scratch fever in cats and humans. Learn how cat scratch fever spreads, the signs you might have it, and how you can avoid getting it (and keep your cat from catching it, too!).

What Is Cat Scratch Fever and What Does It Look Like?

Cat scratch fever (also called cat scratch disease) is an infectious disease in humans caused by the bacteria Bartonella hensela. Children between the ages of five and nine, young adults, and those with compromised immune systems are more prone to symptoms and infection, but people of all ages can get sick.

Cat scratch fever first presents as a bump, or a few bumps, where an infected cat bit, scratched, or licked you, explains Steven McGaughey, MD, Assistant Professor, Department of Emergency Medicine at Oregon Health & Science University. But, this first sign of infection could be hidden in the fold of the skin and missed, he adds.

What Causes Cat Scratch Fever?

Fleas carry bacteria that causes cat scratch fever. Less commonly, it's spread by biting parasites like ticks and flies. "The process begins with a flea biting a cat and feeding on the cat's blood," explains Erin Katribe, DVM, Medical Director of Best Friends Animal Society. "The cat may become infected with the organism and then can transmit it to another flea, which in turn, may transmit it to another cat."

Once cats carry the bacteria, they typically show no symptoms. The few cats that are symptomatic, may have the following signs of cat scratch fever, according to Katribe:

Infected cats transfer the bacteria to people by scratching or biting them, or licking an open wound. "Cats that have fleas carrying the bacteria scratch themselves, causing flea dirt to be present on their claws," Katribe explains. "And they then scratch a person, causing a wound that is contaminated with the flea dirt."

Cat Scratch Fever Symptoms in Humans

The first symptom of cat scratch fever in humans is an easy-to-miss bump, or group of bumps, at the exposure site. The rash develops three to 10 days after the bite, lick, or scratch and usually goes away on its own one to three weeks after developing. In healthy adults, the immune system typically stops the infection there.

If the infection persists, it makes its way to the lymph nodes about two weeks after the initial exposure. The lymph nodes become swollen and painful, eventually forming a one-half to two-inch hard mass under the skin. "This can occur at different places on the body depending on where the infection site is, however, the head, neck, and arms are most common," McGaughey says.

My cat-scratch-fever lump developed in my armpit and while I didn't have other symptoms, McGaughey says these other signs of infection are common:

  • Fever
  • Fatigue
  • Decreased appetite
  • Headache

Cat scratch fever in humans is typically not life-threatening. It's self-limiting and symptoms may persist up to a month alongside treatment. Long-term effects are rare, but McGaughey says in patients with a comprised immune system, a secondary infection of the heart muscle, spleen, brain, eyes, and bones is possible.

As for the kitty spreading cat scratch fever, she'll likely remain asymptomatic with a transient illness only presenting during times of prolonged stress.

Is Cat Scratch Fever Contagious?

Cat scratch fever is commonly spread through an infected cat to a human (aka a zoonotic disease), and rarely passes from flea to human. If you're wondering if cats can spread Bartonella hensela to one another through general contact, experts say it's not likely. But an infected cat could spread her fleas to household pets including other cats and dogs. Infection by Bartonella in dogs is rarely transmitted to humans but could cause symptoms in pups.

McGaughey says there are cases of multiple human family members contracting cat scratch fever, but it's likely due to the household kitty making her rounds. There's no evidence that the disease is contagious between humans.

Cat Scratch Fever Treatment Options

Upon discovering the lump under my arm, my parents rushed me to the emergency room. While an understandable reaction, McGaughey says cat scratch fever rarely requires hospitalization.

Medication

Many cases of cat scratch fever resolve without treatment in the comfort of your home, McGaughey says. For cases with severe symptoms, a course of antibiotics prescribed by your healthcare provider will do the trick.

Veterinary Treatment

Because most cats show no symptoms of carrying Bartonella hensela, veterinary treatment isn't common. Katribe says if a cat is treated for the bacteria, a two- to four-week course of antibiotics is recommended. But the best medicine of all is flea treatment and prevention.

Can Cat Scratch Fever Go Away on Its Own?

In both cats and humans, cat scratch fever could run its course and then disappear. However, a course of antibiotics can help get rid of it faster.

How to Prevent Future Cases of Cat Scratch Fever for You and Your Pets

"The best way to prevent infection is to prevent fleas," Katribe says. If you're wondering how to spot and treat fleas in cats, we're rounded up tips from the experts plus the most effective flea treatments for your furry BFF.

If you have cuts or other open wounds, McGaughey says it's best not to handle cats or kittens. In the unfortunate situation that you get a love bite or are otherwise exposed to cat saliva or flea dirt, thoroughly wash the area with soap and water. If you notice any signs of redness or swelling, contact your primary care physician for treatment.