Cat scratch disease (CSD) is an illness caused by the bacterium Bartonella henselae. Almost half of all cats carry the infection at some point. The infection does not make cats sick. However, the scratch or bite of an infected cat can cause symptoms in people, including

• Swollen lymph nodes, especially around the head, neck, and upper limbs
• Fever
• Headache
• Fatigue
• Poor appetite

For people with weak immune systems, CSD may cause more serious problems. The best way to avoid CSD is to avoid rough play with cats that could lead to scratches or bites. If you do get a scratch or bite, wash it well with soap and water. If the bite or scratch gets infected or if you have symptoms of CSD, call your doctor.

Cat scratch disease (CSD) is a bacterial infection that primarily affects the lymph nodes. It is typically caused by the bacteria bartonella (Bartonella henselae). It is usually transmitted by being scratched or bitten by a cat, but rarely, no scratch or bite is involved. Symptoms frequently include the formation of a small bump at the site of the scratch or bite, followed by fever and swollen lymph nodes (lymphadenopathy) within 1-3 weeks. Lymphadenopathy commonly resolves on its own within a few months, but in some cases it may persist for up to 2 years. People with weakened immune systems (and less commonly, people with healthy immune systems) may develop more widespread disease and additional symptoms or neurological complications, which can be severe. In most cases, particularly in children and adolescents, having CSD once means that it cannot occur again. The recurrence of symptoms months after disease onset has been reported in a few adults with CSD.

Treatment in mild or moderate cases typically involves medicines or strategies to improve symptoms, such as using fever reducers, pain relievers, or local heat over the affected lymph node(s). In more severe or systemic cases, management may involve lymph node aspiration and/or antibiotics.

Cat scratch disease (CSD) is a bacterial infection spread by cats. The disease spreads when an infected cat licks a person’s open wound, or bites or scratches a person hard enough to break the surface of the skin. About three to 14 days after the skin is broken, a mild infection can occur at the site of the scratch or bite. The infected area may appear swollen and red with round, raised lesions and can have pus. A person with CSD may also have a fever, headache, poor appetite, and exhaustion. Later, the person’s lymph nodes near the original scratch or bite can become swollen, tender, or painful.

Wash cat bites and scratches well with soap and running water. Do not allow cats to lick your wounds. Contact your doctor if you develop any symptoms of cat scratch disease or infection.

CSD is caused by a bacterium called Bartonella henselae. About 40% of cats carry B. henselae at some time in their lives, although most cats with this infection show NO signs of illness. Kittens younger than 1 year are more likely to have B. henselae infection and to spread the germ to people. Kittens are also more likely to scratch and bite while they play and learn how to attack prey.

How cats and people become infected

Cats can get infected with B. henselae from flea bites and flea dirt (droppings) getting into their wounds. By scratching and biting at the fleas, cats pick up the infected flea dirt under their nails and between their teeth. Cats can also become infected by fighting with other cats that are infected. The germ spreads to people when infected cats bite or scratch a person hard enough to break their skin. The germ can also spread when infected cats lick at wounds or scabs that you may have.

Serious but rare complications

People

Although rare, CSD can cause people to have serious complications. CSD can affect the brain, eyes, heart, or other internal organs. These rare complications, which may require intensive treatment, are more likely to occur in children 5-14 years of age and people with weakened immune systems.

Cats

Most cats with B. henselae infection show NO signs of illness, but on rare occasions this disease can cause inflammation of the heart—making cats very sick with labored breathing. B. henselae infection may also develop in the mouth, urinary system, or eyes. Your veterinarian may find that some of your cat’s other organs may be inflamed.

What is cat scratch disease (CSD)?

Cat scratch disease is a bacterial infection caused by Bartonella henselae bacteria. Most infections usually occur after scratches from domestic or feral cats, especially kittens. CSD occurs wherever cats and fleas are found. The most common symptoms include fever; enlarged, tender lymph nodes that develop 1–3 weeks after exposure; and a scab or pustule at the scratch site. In the United States, most cases occur in the fall and winter and illness is most common in children less than 15 years old.

My cat is completely healthy. How can it carry an infection?

Cats become infected with Bartonella (the bacteria that cause cat scratch disease) through flea bites or, less commonly, fights with other infected cats or feline blood transfusions. While some cats become ill, most simply carry the bacteria in their blood without getting sick. Some studies have found the Bartonella bacteria in the blood of up to 1/3 of healthy cats, particularly kittens.

Should I get my pet treated for Bartonella, just to be safe?

Treatment is not recommended unless your pet becomes sick. Treating Bartonella with antibiotics can take a long time and it’s considered safer and more practical to let the pet handle the infection naturally. For cats that do become sick, the illness usually consists of fever for 2-3 days, with the cat recovering on its own. Symptoms requiring veterinary care include fever, vomiting, lethargy, red eyes, swollen lymph nodes or decreased appetite.

My daughter got scratched by the neighbor’s kitten and now my husband is worried about “cat scratch disease.” How worried should we be?

Most cat scratches do not result in cat scratch disease, and short of cleaning the wound with soap and water, there is no particular action to take. If your child develops a fever; enlarged, tender lymph nodes that develop 1–3 weeks after being scratched; or a pustule at the scratch site, please take her to your health care provider. Treatment with antibiotics is usually not necessary but may help reduce lymph node swelling.

I have a medical condition that affects my immune system. Should I give my cat away?

If you’re HIV-positive, are being treated for cancer, or have any other condition that might disrupt your immune system, you can keep your cat. Just keep the following points in mind:

• Keep the cat indoors.
• Avoid rough play with cats and situations in which scratches are likely. Declawing is not recommended to prevent cat scratch disease.
• Promptly wash any cat scratches or bites with soap and water.
• Avoid contact with fleas.
• Treat the cat with a flea control product recommended by your veterinarian.
• It’s not necessary to test or treat a healthy cat for Bartonella.
• If you are getting a cat, make sure it’s at least a year old, in good health, and free of fleas. Avoid stray cats and cats with flea infestations.

People

Talk to your doctor about testing and treatments for CSD. People are only tested for CSD when the disease is severe and the doctor suspects CSD based on the patient’s symptoms. CSD is typically not treated in otherwise healthy people.

Cats

Talk to your veterinarian about testing and treatments for your cat. Your veterinarian can tell you whether your cat requires testing or treatment.

I have been suffering from fatigue and memory problems for the past year. Should I be tested for Bartonella infection?

There are many reasons why people might experience fatigue and memory problems. It’s unlikely that Bartonella is the cause of these issues. Work with your primary care physician to determine if a specialist is needed.

I heard that there are newer testing methods from laboratories that specialize in Bartonella testing. Are these new tests accurate?

Although CDC typically recommends FDA-cleared tests, there are not currently any Bartonella tests on the market that meet this standard. There are some things that you should keep in mind when evaluating the accuracy of a lab test.

• First, any laboratory that performs Bartonella serologic testing should provide you with information regarding the accuracy of the test.
• Second, be aware that while some labs may report that their tests find 100% of infected patients, this is unrealistic—the potential for false positives (and false negatives) almost always exists.
• Finally, it is important for all abnormal test results to be interpreted with your health care provider in the context of your medical history.

I got a tick bite. My friend said I should get tested for Lyme disease and Bartonella. Is that true?

We don’t recommend it. To date, no study in the United States has shown that Bartonella can be transmitted to humans by ticks. Transmission studies with ticks have only used mice and artificial feeding systems. A single study showed that one species of tick in Europe could transmit a specific species of Bartonella to mice in a laboratory setting.

Other studies have identified Bartonella in ticks, probably from ticks feeding on animals that carry Bartonella. This doesn’t mean that the bacteria can be transmitted from the tick to a person or that the bacteria can survive in the tick for any length of time.

Unfortunately there is a great deal of misinformation regarding multiple tickborne infections (called coinfections) on the internet. The possibility of having several tickborne infections at once or having pathogens such as Bartonella that have not been shown to be tickborne, is extremely unlikely.

People

Do:

• Wash cat bites and scratches right away with soap and running water.
• Wash your hands with soap and running water after playing with your cat, especially if you live with young children or people with weakened immune systems.
• Since cats less than one year of age are more likely to have CSD and spread it to people, persons with a weakened immune system should adopt cats older than one year of age.

Do not:

• Play rough with your pets because they may scratch and bite.
• Allow cats to lick your open wounds.
• Pet or touch stray or feral cats.

Cats

Control fleas

• Keep your cat’s nails trimmed.
• Apply a flea product (topical or oral medication) approved by your veterinarian once a month.
  • BEWARE: Over-the-counter flea products may not be safe for cats. Check with your veterinarian before applying ANY flea product to make sure it is safe for your cat and your family.
• Check for fleas by using a flea comb on your cat to inspect for flea dirt.
• Control fleas in your home by
  • Vacuuming frequently
  • Contacting a pest-control agent if necessary

Protect your cat’s health

• Schedule routine veterinary health check-ups.
• Keep cats indoors to
  • Decrease their contact with fleas
  • Prevent them from fighting with stray or potentially infected animals