Cat scratch disease (CSD), Bartonella henselae

People can get CSD from the scratches of domestic or feral cats, particularly kittens. The disease occurs most frequently in children under 15. Cats can be infested with infected fleas that carry Bartonella bacteria. These bacteria can be transmitted from a cat to a person during a scratch. Some evidence suggests that CSD may be spread directly to people by the bite of infected cat fleas, although this has not been proven.

CSD occurs worldwide, wherever cats live. Stray cats may be more likely than pets to carry Bartonella. In the United States, most cases of CSD occur in the fall and winter.

Ticks may carry some species of Bartonella bacteria, but there is currently no causal evidence that ticks can transmit Bartonella infection to people through their bites.

Trench fever, Bartonella quintana

Trench fever is transmitted by the human body louse. Because of its association with body louse infestations, trench fever is most commonly associated with homelessness or areas of high population density and poor sanitation. Trench fever received its name during World War I, when many soldiers fighting in the European trenches were infested with infected body lice and became sick with the disease.

Trench fever occurs worldwide. Cases have been reported from Europe, North America, Africa, and China.

Carrión’s disease, Bartonella bacilliformis

Carrión’s disease, formerly known as bartonellosis, is transmitted by bites from infected sand flies (genus Lutzomyia). Carrión’s disease only occurs in the Andes Mountains at 3,000 to 10,000 ft. in elevation in western South America, including Peru, Colombia, and Ecuador. Most cases are reported in Peru.

A few cases of Oroya fever and verruga peruana (Peruvian warts) have been reported in travelers who returned from the Andean highlands in South America, but the risk is low. Much is still unknown about which animals may be a part of the natural cycle of this disease.

Cat scratch disease (CSD), Bartonella henselae

• Low-grade fever
• Enlarged, tender lymph nodes that develop 1–3 weeks after exposure
• A papule or pustule at the site of the scratch

Rarely, eye infections, severe muscle pain, or encephalitis (swelling of the brain) may occur.

Trench fever, Bartonella quintana

• Fever (may occur once or repeatedly)
• Headache
• Rash
• Bone pain, mainly in the shins, neck, and back

Carrión’s disease, Bartonella bacilliformis

This disease has two distinct phases:

• Oroya fever: During this phase, fever, headache, muscle aches, abdominal pain, and severe anemia may occur.
• Verruga peruana (Peruvian warts): During this later phase, growths form under the skin and develop into red-to-purple vascular sores that can become raw or bleed.

Other complications

Bacillary angiomatosis

Bacillary angiomatosis (caused by B. henselae or B. quintana) and bacillary peliosis (caused by B. henselae) occur primarily in people with weakened immune systems, such as those with advanced HIV infection. Bacillary angiomatosis may result in lesions in the skin, under the skin, in bone, or in other organs. Bacillary peliosis causes sores in the liver and spleen.

Subacute endocarditis

Many Bartonella species can cause infection of the heart valves (subacute endocarditis), which is often culture negative.

Cat scratch disease (CSD), Bartonella henselae

• Avoid rough play with cats, particularly strays and kittens, to prevent scratches. This is especially important for people who have weakened immune systems. Wash hands promptly after handling cats.
• Treat cats for fleas using fipronil and other spot-on treatments. Check with your veterinarian. Products that contain permethrin should not be used on cats.
• Use a flea collar or similar topical preventive on dogs (fipronil, methoprene, imidocloprid, or permethrin), especially if you have both cats and dogs in your household.
• Keep cats indoors and away from stray cats.
• People who have weakened immune systems should avoid owning cats less than one-year-old.

Trench fever, Bartonella quintana

• Avoid exposure to human body lice. Body lice are typically associated with crowded living conditions and limited access to bathing and clean clothes.
• Do not share clothing, beds, bedding, and towels used by a person who might have body lice.
• Information about treating body lice is also available.

Carrión’s disease, Bartonella bacilliformis

• Use insect repellents and wear long-sleeved shirts and long pants to avoid sand fly bites in areas where Carrión’s disease is common (South America). If possible, limit outdoor activities at dawn and dusk, when sand flies are most active.

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.

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.