Can My Cat Make Me Sick with Cat Scratch Fever?

Cat scratch fever, sometimes referred to as cat scratch disease, is one of a handful of illnesses known as zoonotic diseases that can (although rarely do) spread from animals to humans. Around 40% of all cats carry the cat scratch fever bacteria — Bartonella henselae — at some point in their lives, usually during kittenhood, according to the U.S. Centers for Disease Control and Prevention (CDC). Cat scratch fever itself is incredibly rare, and it is even rarer that the disease is fatal for cats or humans. This bacterial infection can be passed to humans through a cat’s claws or teeth when it breaks the skin by scratching or biting.

Cat Scratch Fever Causes

Cats become infected with the bacteria that causes cat scratch fever after being bitten by fleas that carry it. They can also develop the condition if the droppings from infected fleas get into wounds or scratches on the body.

The route to human transmission of the Bartonella henselae bacteria occurs when this bacteria becomes trapped beneath the cat’s claws or in its teeth, usually from the cat cleaning itself, scratching, or fighting with other infected cats, and then the cat scratches or bites the human, breaking the skin.

Cats also spread the bacteria through their saliva if the saliva finds itself into the whites of the human’s eyes or to an open wound on the human’s body. In some cases (albeit rare), people have acquired cat scratch fever from the direct bite of a flea or tick carrying the Bartonella henselae bacteria. And while the animal-to-person route of transmission is well-documented and a real concern, person-to-person contact of cat scratch fever is not possible. It is not contagious between humans.

Cat Scratch Fever Symptoms

Cats usually display no symptoms of cat scratch fever. In fact, most appear quite healthy. In humans, several symptoms can be observed, including:

• Bumps or blisters within three to 10 days at the site of a cat bite or scratch
• Swollen lymph nodes, noticeable within one to seven weeks following a bite or scratch from an infected cat
• Lethargy, fatigue, tiredness or sluggishness
• Fever
• Aching joints

Treatment for Cat Scratch Fever

Luckily, cat scratch fever is rarely cause for serious concern, and treatment is not typically necessary. Most cat scratch fever infections are benign, disappearing on their own after a few months. Symptoms such as bumps or blisters may linger for one to three weeks while swollen lymph nodes may stick around up to four months.

People who exhibit symptoms of cat scratch fever and experience high fever and pain should see a doctor right away. In some instances, antibiotics may be necessary to treat the symptoms of the condition, especially among people with weakened immune systems (and fatalities have been reported). Serious infections of the brain, eyes, heart and other vital organs may result.

Cats rarely become sick from cat scratch fever. However, it is not unheard of in rare instances for a cat to develop heart inflammation from the disease, which can result in sickness and difficulty breathing — and necessitating a trip to the emergency veterinarian right away.

At-Risk Populations for Cat Scratch Fever

Among cats, the most at-risk populations for cat scratch fever are kittens and strays or feral cats. This is because both are at heightened risk for fleas. Moreover, cats living in warmer regions are more susceptible to cat scratch fever because the warmer the climate, the better the conditions for fleas to reproduce.

Among humans, cat scratch fever is more often seen in children up to age six and in people with immune systems weakened by disease or age. According to sources, people are at the highest risk of becoming seriously sick from cat scratch fever if they have HIV, AIDS, diabetes or cancer, or if they are pregnant or the recipient of a transplanted organ. 

Other Zoonotic Diseases

Cat scratch fever is not the only disease that can be passed from your pet to human hosts. Other zoonotic diseases include:

• Common in felines, roundworms typically make the jump from pet to human via infected feces. This puts those who are tasked with changing and cleaning the litter box or children who are more apt to come into contact with infected soil at the greatest risk for the condition. Symptoms of roundworm infection include shortness of breath, coughing, pain in the abdominal region, fatigue and diarrhea.
• Ringworm is not a worm at all but a type of skin fungus that can spread from cats to humans. Transmission occurs via direct contact with an infected animal. The only discernible symptom in both felines and humans is the same: the development of bald, scaly-looking circles on the skin.
• Cats contract toxoplasmosis, a type of parasitic infection, by eating infected prey or raw meat. The toxoplasmosis parasite lives in the cat’s intestines and is expelled in fecal matter — and exposure to feces (through infected dirt or litter box duty) is how it gains entry to human hosts. Because toxoplasmosis can transfer from mother to child in utero, it is important that pregnant women avoid cleaning the litter box.
• The bite of a cat infected with rabies can pass to a human.

Anyone exposed to any of these zoonotic diseases should see a doctor right away to determine the appropriate course of treatment.

Avoiding Cat Scratch Fever and Other Zoonotic Diseases

It is possible to avoid cat scratch fever and other types of zoonotic diseases. Cleanliness is important in avoiding cat scratch fever and other zoonotic diseases mentioned above.

• Take care of any flea problems on your pet or in your home as soon as possible after discovery.
• Treat your cat for fleas regularly to avoid flea issues.
• Avoid aggressive or feral cats when possible.
• Do not place open wounds or your face near your cat.
• Avoid rough play to reduce the chance of scratches and bites.
• Wash any scratch or bite immediately with fresh water and antibacterial soap.
• Never allow a cat to lick any open wounds or scratches on your body. The saliva from your cat can deposit bacteria into your wound, potentially worsening the wound, causing an infection, or even resulting in a zoonotic disease.
• Always wear gloves when you’re cleaning the litter box.
• If you’re pregnant, then assign litter box duties to someone else.
• After feeding, grooming, or petting your cat, always wash your hands.
• Check your cat’s skin often for signs of ringworm.

Although cat scratch fever is rare and complications or fatalities from it are even rarer still, avoiding it altogether can be as simple as maintaining a regular flea treatment regimen and practising proper hygiene in general.