Cat scratch fever, known medically as cat scratch disease, affects roughly 12,500 people per year in the United States. That works out to about 4.7 cases per 100,000 people under age 65. It’s common enough that most doctors recognize it quickly, but uncommon enough that the average cat owner will never experience it.
Who Gets It Most Often
Children between ages 5 and 9 have the highest infection rate of any age group, at 9.4 cases per 100,000, roughly double the overall average. Kids under 14 account for about a third of all diagnoses. This makes sense: young children are more likely to play roughly with cats and kittens, picking up scratches and bites in the process.
Women and girls make up 62% of outpatient diagnoses and about 56% of hospitalizations. Among adults, the gap between women and men widens with age, with women 60 to 64 having the highest adult incidence at 6.6 cases per 100,000. The reasons likely involve higher rates of cat ownership and close contact with pets among women, though the data doesn’t confirm a biological explanation.
Geography and Seasonal Patterns
Where you live matters. The southern United States has the highest rate at 6.4 cases per 100,000, nearly 50% above the national average. Warmer, more humid climates support larger flea populations year-round, and fleas are the key link in the chain of transmission. Studies in Japan found the same geographic pattern: southwestern regions with warmer climates reported significantly more cases than northern areas.
Infections also follow a seasonal rhythm. Positive antibody rates for the bacteria peak between September and January, then drop between March and July. Late summer and fall are prime kitten adoption season, and flea activity tends to surge in warm months, setting up a wave of infections that shows up in testing a few weeks later.
Kittens Carry Far More Risk Than Adult Cats
Not all cats pose the same level of risk. Cats younger than one year are about 5.3 times more likely to carry the bacteria than older cats. Kittens haven’t yet built up the immune defenses needed to clear the infection from their bloodstream, so the bacteria persist longer and at higher levels. They’re also more likely to scratch and bite during play, creating more opportunities for transmission.
Two other factors increase the odds that a cat is carrying the bacteria: not being neutered (3.5 times higher risk) and not receiving proper flea control (3.1 times higher risk). Outdoor and stray cats, which tend to have heavier flea burdens, are also more likely to be infected. The bacteria live in flea feces, which collect in a cat’s fur. When a cat scratches you, flea feces can be pushed into the wound, delivering the bacteria directly into your skin.
Most Cases Stay Mild
The vast majority of people diagnosed with cat scratch disease never need to be hospitalized. Of the roughly 12,500 annual cases in the U.S., about 12,000 are treated as outpatients and only around 500 require a hospital stay. That’s a hospitalization rate of about 4%. The typical case involves swollen lymph nodes near the scratch site, a low fever, and fatigue that resolves on its own over a few weeks.
Hospitalized patients tend to look different from the typical case. They’re significantly more likely to be male and between 50 and 64 years old, a group that may be more prone to complications or delayed diagnosis. In rare instances, the infection can spread beyond the lymph nodes and affect the eyes, nervous system, or other organs. Eye involvement can include inflammation of the optic nerve or retina, and while treatable, these complications require prompt medical attention.
Why the Real Number Is Likely Higher
The 12,500 figure comes from insurance claims data collected between 2005 and 2013, which means it only captures people who saw a doctor and received a formal diagnosis. Many mild cases likely go unrecognized. Someone who gets a scratch from a cat, notices a swollen lymph node for a couple of weeks, and then feels fine may never seek care at all. The true number of infections each year is almost certainly higher than the official count, though by how much is difficult to estimate.
Reducing Your Risk
Keeping fleas off your cat is the single most effective way to prevent cat scratch disease. The bacteria travel from cat to cat through flea bites, and from cat to human through flea feces contaminating a scratch wound. A cat with no fleas is far less likely to carry the bacteria in the first place.
Beyond flea control, a few practical habits lower your risk. Wash cat scratches and bites promptly with soap and water. Avoid rough play that encourages scratching, especially with kittens. Don’t let cats lick open wounds or broken skin. If you’re adopting a kitten, starting flea prevention early is particularly important given kittens’ much higher carriage rates. None of this means you need to avoid cats entirely. Cat scratch disease is real but uncommon, and for the vast majority of people who get it, it resolves without lasting effects.