What is cat scratch fever?

Cat scratch fever, also known as cat scratch disease (CSD), is a zoonotic infection that occurs when someone is exposed to Bartonella hensii germ. Zoonoses are types of infections or diseases that spread from animals to humans or from humans to animals. In the case of CSD, cats are responsible for most infections in humans.

About 12,000 people are diagnosed with cat scratch fever each year, and 500 will be hospitalized with the infection. Read on to learn more about cat scratch fever and how the infection affects humans.

What are the symptoms of cat scratch fever?

Cats can be considered carriers of the bacteria that cause CSD because they don’t always get sick with CSD, and they can infect other people. Since they rarely show symptoms, it can be difficult to tell if a cat is infected.

When a person is infected, they may experience the following symptoms:

  • Fever, especially a fever over 100.9 degrees Fahrenheit that persists for several weeks or is undiagnosed
  • Lumps or blisters (usually red or brown) from scratches or bites that appear 3 to 14 days after the injury
  • One or more swollen lymph nodes, usually on the same side as the cat scratch or bite (most people have only one swollen lymph node, and the swelling may persist for months)
  • Muscle ache
  • nausea
  • feeling unwell or sick (ill)
  • stomach ache
  • loss of appetite
  • eye and pink eye inflammation

Rare but serious complications of CSD

In some cases, people with CSD may experience rare but serious complications, such as:

  • liver inflammation
  • Inflammation of the brain that causes headaches, neck stiffness and light sensitivity
  • Bone inflammation
  • Arthropathy, a joint disease similar to arthritis
  • Life-threatening inflammation of the lining of the heart chambers and valves
  • Enlarged spleen (splenomegaly)

These conditions may require hospitalization as soon as possible.

What is the cause of cat scratch fever?

Cats are responsible for cat scratch fever, although in rare cases humans can contract the disease-causing bacteria directly from infected fleas. Fleas are usually responsible for transmitting the infection to cats. Other mammals that can carry bacteria include guinea pigs, rabbits, and in some cases dogs.

When cats or other infected animals bite or scratch their skin, the bacteria can spread to the bloodstream. It can also spread if an infected animal licks the wound.

Are all cats infected with the bacteria that cause cat scratch fever?

According to published in Advances in Dermatology and Allergy, up to 90% of cats are thought to have a bacterial infection that causes CSD. However, the Centers for Disease Control and Prevention (CDC) recommends that only 40 percent of cats will be infected with this bacteria in their lifetime.

The CDC also states that kittens under the age of 1 are most likely to develop the disease. Although the reason for the difference in numbers is unclear, it may be because of the location and cat population used in each study.

How is cat scratch fever diagnosed?

To diagnose CSD, your doctor will perform a physical examination and collect your symptoms, health history, and records of possible exposure to cats who may have the disease. They may also do blood tests to look for antibodies, which are special proteins the body makes to help fight bacterial infections.

These tests, while good at confirming the diagnosis, are not always effective in the initial stages of infection. This is because it can take weeks for the body to produce enough antibodies to determine if you have CSD. Therefore, these tests can often tell if someone has been infected in the past, but not whether they have an active infection.

A PCR (polymerase chain reaction) test can be used to determine if there is any evidence of bacteria in a person’s blood. Therefore, PCR tests can be used to diagnose active infection of the disease.

when to call the doctor

While most CSD infections clear up on their own, you should see your doctor if there is redness and swelling around the wound that starts to expand, or if you have a fever a few days after being scratched or bitten by a cat, or if you develop swelling, or if you have pain in your lymph nodes.

How is cat scratch fever treated?

Treatment for CSD will depend on the severity of the infection. As mentioned above, many situations will resolve themselves. For those who do need treatment, the antibiotic drug azithromycin (Zithromax) is usually given for five days. Antibiotics are medicines designed to kill harmful bacteria in the body.

Other antibiotics that can be used include:

  • Rifampicin (Rifampicin)
  • Ciprofloxacin (Cipro)
  • trimethoprim-sulfamethoxazole (Bactrim, Septra)

Rifampicin and antibiotic resistance in CSD

Research has shown that rifampicin is becoming less effective due to antibiotic resistance, a term used to describe the ability of a bacterium or bacteria to defeat antibiotics designed to kill it. Because of this, some medical experts believe that rifampicin should be used in combination with other antibiotics such as azithromycin or gentamicin (galamycin).

What is the prognosis for patients with cat scratch fever?

Most people with CSD recover completely from the infection with the right treatment, or even recover on their own without any form of treatment.

Serious complications occur in approximately 5% to 10% of patients; however, less than 1.3% of CSD cases are fatal. Once a person is infected with the bacteria, they are immune to it for the rest of their lives, so there is no risk of being exposed to it again.


Cat scratch disease, or cat scratch fever, is a zoonotic bacterial disease that affects anyone who comes into contact with it. The disease is primarily transmitted by infected cats; however, other domestic animals can also contract and transmit the disease, such as guinea pigs, rabbits, and dogs.

In most cases, having CSD does not seriously affect your health, and many people recover from mild symptoms without treatment. For those who do have more severe health effects, receiving appropriate antibiotic treatment is often associated with a full recovery.

VigorTip words

You may be concerned about getting cat scratch fever, especially if you are a cat owner. However, not all cats can get the bacteria, so not all cats can pass it on to you. Most cats don’t have any symptoms, so it can be difficult to tell if your cat is infected.

If you think your cat may have this disease, you can take them to the veterinarian for a checkup. To prevent your cat from giving you a bacterial infection, trim their claws and immediately wash any cat scratches or bites with soap and water. Also, since fleas are the biggest culprit in spreading infection to cats, you can control fleas by keeping your cat indoors and checking for fleas regularly.

Frequently Asked Questions

  • Is cat scratch fever serious?

    Most cases of cat scratch fever are mild and require little treatment. However, serious health effects can occur resulting in hospitalization and the need for immediate treatment. Call your doctor if you develop any serious signs of CSD, such as high and unending fever or sore lymph nodes, as you may need treatment.

  • Will cat scratch fever go away?

    Symptoms of cat scratch fever go away on their own or with treatment. The body also develops lifelong immunity after contracting the disease.

  • Who usually suffers from severe CSD complications?

    Children between the ages of 5 and 14 are most at risk of developing a rare complication of CSD. People of any age with weakened immune systems are also at higher risk for severe CSD and the symptoms that come with it.