Cat scratch fever occurs when a person is bitten, scratched, or licked by a cat infected with the bacteria Bartonella henselae.
The infection doesn’t usually cause severe complications. However, it’s possible that it can in people with weak immune systems. Knowing the causes and symptoms can ensure a person receives swift treatment.
Cats can transmit several types of infections to humans. Some of these diseases can be severe. Carrying out routine care for a cat often reduces the risk of many of these diseases.
Causes of cat scratch fever
A person can get cat scratch fever if they are scratched or bitten by an infected cat. The B. henselae bacteria live in a cat’s saliva, and can also be passed to a person through an open area of skin.
People are most likely to experience cat scratch fever in the fall and winter when they’re inside and play with their cats. Kids are more likely than adults to have the condition. They can play with cats more roughly, making them more likely to be scratched.
Symptoms of cat scratch fever
Cat scratch fever doesn’t usually cause symptoms in the first few days after a person is exposed. During this time, the bacteria are multiplying in the body.
About 3 to 10 days after a person is scratched, they may notice a small bump or blister on the affected area. Doctors call this an inoculation lesion. These lesions are commonly seen on the:
Cat scratch fever symptoms appear a few days after the bite, lick, or scratch has happened.
A few weeks later, a person will usually see the lymph nodes near the lesion swollen or tender.
Lymph nodes are responsible for filtering bacteria and other particles as well as creating immune system cells. They usually feel like small, spongy, round or oval bumps.
If a person was bitten or scratched on the arm, the lymph nodes under the arm or near the elbow may be especially tender.
Sometimes, the lymph nodes swell as much as 2 inches across. They may be warm to the touch, pus-filled, or red in color. The lymph nodes may remain swollen for anywhere from 2 to 4 months after the initial infection.
Most people only have swollen lymph nodes as a symptom. Other symptoms associated with cat scratch fever include:
- Abdominal pain
- Loss of appetite
- Fever, typically no higher than 101°F
- Joint pain
- Sore throat
Complications of cat scratch fever
Cat scratch fever doesn’t usually cause severe symptoms. However, some people may develop a high fever that doesn’t seem to go away with time.
Some people can also experience infections in the bones, joints, liver, lungs, or spleen. According to the Centers for Disease Control and Prevention (CDC), the most severe symptoms usually occur in children ages 5 and under.
While cat scratch fever isn’t a condition that usually requires emergency care, there are always exceptions. A person should contact their doctor immediately if they experience the following symptoms:
- A cat bite or scratch that is not healing or is getting worse
- The red area around a bite or scratch is enlarging
- A high fever that lasts more than 2 days after being bitten or scratched
- High levels of pain
Diagnosing cat scratch fever
Cat scratch fever can be hard to diagnose as the symptoms are similar to a lot of other conditions. A doctor will ask about a person’s medical history and any interactions a person may have had a cat.
A doctor will then conduct a physical examination, looking at the scratched area and any swollen lymph nodes. Examination and medical history are often enough to make a diagnosis.
The doctor may order additional tests to make sure another condition isn’t causing the symptoms. They could take a sample of blood and send it to a lab to determine what type of bacteria is growing.
Doctors can also order a blood test that specifically tests for cat scratch fever.
Treatments for cat scratch fever
As most cases of cat scratch fever are mild, a doctor won’t always prescribe a treatment. If symptoms are moderate to severe, they may prescribe an antibiotic.
At-home treatments for the condition include bed rest and an over-the-counter pain reliever if the lymph nodes are painful or especially tender.
While children don’t have to stop playing, they should avoid hitting or interfering with the affected lymph nodes.
Once a person has had cat scratch fever once, they’re unlikely to get the disease again.
Preventing cat scratch fever
While cats can transmit cat scratch fever to people, people don’t usually pass it to others. If one family member is affected, others should practice caution around the family cat as the cat could infect them too.
An episode of cat scratch fever also doesn’t mean a family should necessarily get rid of their pet. However, they can practice the following preventive techniques:
Preventing a cat from getting fleas can help reduce the risk of cat scratch fever.
- Adopting a cat that is older than 1 year if a person is at high risk for adverse symptoms of cat scratch fever (kittens are most likely to carry the disease)
- Avoiding rough play around a cat or kitten
- Never allowing a cat to lick wounds or open areas of skin
- Never petting stray or feral cats
- Washing hands and any other affected areas after playing with a cat
- Vacuuming a home frequently to avoid fleas
- Practicing flea prevention to reduce the risk a cat could get the infection
- Contacting a pest control company if a lot of fleas have been identified in a home
Recognizing the condition in your cat
According to the CDC, an estimated 40 percent of cats carry the B. henselae infection at some point in their lives. Most of the time, cats that carry the infection don’t show signs of illness.
Cats get the infection when they scratch and bite at fleas that infect them or fight with cats that are infected. If a cat has fleas or visible scratches, these could be signs a person should practice caution when handling their cat. Once a cat is infected, it can carry the disease for several months.
In rare cases, cat scratch disease can cause severe symptoms in cats, including inflammation of the heart. Cats may have difficulty breathing due to this. Upon examination, a vet may also identify inflammation in the eyes, mouth, or urinary system.
Diagnosis and treatment
A vet can inspect a cat for fleas and make recommendations regarding flea prevention and avoiding scratches and bites.
While there is a blood and fluid test available for the Bartonella bacteria, doctors don’t usually recommend it for cats that don’t have symptoms. The bacteria are very common, and the test can be unreliable.
Cats aren’t usually treated with antibiotics unless they have noticeable symptoms.
Taking steps to reduce fleas in a cat can reduce the likelihood of cat scratch fever. People can care for their cats by doing the following:
- Applying or administering a vet-approved flea treatment on a regular basis
- Keeping a cat indoors to avoid contact with stray or infected animals
- Keeping a cat’s nails trimmed and neat
- Scheduling and maintaining regular check-ups with a vet
Vaccines aren’t currently available against cat scratch disease bacteria.
Other conditions cats can spread
Cats can carry and spread additional diseases besides cat scratch fever. These diseases include:
- Campylobacteriosis: An intestinal infection caused by bacteria
- Cryptosporidiosis: A parasite that causes diarrhea and abdominal cramping
- Plague: This condition isn’t common in the United States, but can occur if a cat is taken to another country
- Rabies: According to Seattle and King County Public Health, cats are the domestic animal most likely to experience a rabies infection
- Ringworm: Kittens are especially likely to carry this disease that causes bald patches on the skin
- Tapeworm: Most common in children, this infection occurs when a person swallows a flea from a cat that is infected with tapeworm larvae
- Toxocara infection: While the condition doesn’t always cause symptoms, it can be associated with serious complications like blindness
- Toxoplasmosis: Toxoplasmosis is of special concern to pregnant women because it can cause complications like miscarriage, affected fetal growth, and eye problems