Bartonella and Lyme Disease: Symptoms and Evidence

Quick answer

Bartonella is a group of bacteria that cause cat-scratch disease, trench fever and Carrion’s disease. CDC says it spreads through cats and their fleas, body lice and sand flies, and that ticks have not been shown to spread it to people. Some researchers and patient groups suspect a tick link to Lyme, but that is not proven.

What the guidelines say

More than 20 Bartonella species are known, but not all cause disease. In the U.S., the most common form of bartonellosis is cat-scratch disease, caused by B. henselae.
B. henselae spreads through scratches from cats that carry infected fleas. B. quintana spreads through the feces of human body lice. B. bacilliformis spreads through sand fly bites in parts of South America. Rarely, infection passes through an organ transplant.
CDC says there is no evidence that Bartonella spreads to people through tick bites. One laboratory study showed transfer from ticks to animals; more research is needed to know whether this happens in nature.
Cat-scratch disease may be diagnosed from symptoms, and antibiotics may shorten it. B. quintana and B. bacilliformis infections need antibiotics.

The three classic Bartonella diseases

Each classic form has its own germ and carrier:

Disease	Species	Spread by	Main features
Cat-scratch disease	B. henselae	Cat scratches or bites, especially from kittens; cat fleas	A small bump at the scratch, then tender, swollen lymph nodes 1 to 3 weeks later; sometimes a long-lasting fever
Trench fever	B. quintana	Body lice (through their feces)	Fever, headache, a brief rash and bone pain in the shins, neck and back
Carrion’s disease	B. bacilliformis	Sand flies in parts of the Andes in South America	An acute phase (Oroya fever: fever, muscle pain, headache, anemia), then red-to-purple skin bumps (verruga peruana)

Trench fever got its name in World War I, when a review estimates nearly a million soldiers were affected. It has reappeared among people experiencing homelessness. CDC’s current pages call Carrion’s disease “South American bartonellosis.”

Bartonella symptoms

For cat-scratch disease, the form most people in the U.S. get, MedlinePlus lists:

A bump, sometimes filled with pus, where the skin was scratched or bitten (often the first sign)
Swollen lymph nodes near the scratch
Tiredness, headache and feeling generally unwell
Fever in some people; less often, poor appetite, sore throat or weight loss

Most cases are not serious, and healthy people usually recover fully. People with weakened immune systems, including people with HIV, can get much sicker and need antibiotics.

Long-term Bartonella symptoms

Well-documented serious or lasting problems include:

Heart valve infection (endocarditis), which may not show up on routine blood cultures.
Eye, brain and bone involvement, such as inflammation of the retina and optic nerve (neuroretinitis), encephalitis or bone infection.
Blood-vessel growths in the skin, bone or liver (bacillary angiomatosis, peliosis hepatis), mainly in people with HIV.

A 2019 review notes that Bartonella can persist in the blood of its hosts, citing case reports of symptoms recurring for up to two years. Advocacy groups describe broader chronic nerve, memory and mood symptoms, but that evidence comes mostly from case reports and small uncontrolled studies.

Lyme and Bartonella: do ticks spread it?

Mainstream view (CDC). Ticks have not been shown to transmit Bartonella to people. Bartonellosis is not among the illnesses on CDC’s diseases transmitted by ticks list.

The evidence people point to.

Bartonella DNA has been found in ticks worldwide. In one New Jersey study cited in a 2019 review, about 6.5% of 168 blacklegged ticks carried B. henselae and about 1% carried both it and the Lyme bacterium.
A 2008 laboratory study found that B. henselae survived in European Ixodes ticks as they molted and passed into blood during artificial feeding.

Why it is not settled. A 2010 review in CDC’s journal Emerging Infectious Diseases found no definitive evidence that ticks pass Bartonella to a host. DNA in a tick does not prove it can transmit live bacteria, artificial feeding differs from a real bite, and a case-control study of cat-scratch disease found no link with tick bites. Even the 2019 review, which leans toward a tick role, says tick transmission of B. henselae has not been definitively shown.

Patient-advocate view. Groups such as LymeDisease.org treat Bartonella as a Lyme co-infection. They say there is “high suspicion” that ticks transmit it, while noting that more research is needed. This is an advocacy position, not an established finding.

What this means in practice: if you are sick after a tick bite and have also had contact with cats, kittens or fleas, tell your provider about both. Knowing what to report is part of step 3 of our plan, recognize the signs. For the infections ticks are known to spread, see our co-infections guide, including babesiosis and anaplasmosis.

“Bartonella rash” and stretch-mark lesions

Some sources say Bartonella causes a streaked rash resembling stretch marks.

A 2020 study in the journal Pathogens looked at 29 people with neuropsychiatric symptoms who tested positive for Bartonella. Of these, 24 reported skin lesions, many of which resembled stretch marks, even though common causes such as pregnancy, obesity, bodybuilding or steroid use were rarely reported.

The authors themselves listed important limits:

There was no comparison group, and participants signed themselves up.
Most were never examined by a dermatologist, photos were taken by participants, and no skin biopsies were done.
They said causation could not be confirmed, partly because Bartonella DNA has also been found in healthy people and blood donors.
Two authors disclosed leadership roles in a company that offers Bartonella testing.

So these lesions are not an established sign of Bartonella. Show new, unexplained skin changes to a clinician. For the rash Lyme causes, see our Lyme rash guide.

What patients tell us

We are collecting real experiences about Bartonella and suspected tickborne co-infections from people who have lived it, shared with their permission. As stories come in, they will appear here, clearly marked as personal experience rather than medical advice.

Share your experience

Testing and its limits

Cat-scratch disease is often diagnosed from symptoms and cat contact. An antibody blood test can confirm it but may cross-react with other germs; PCR or special cultures of lymph node fluid can also help.
Other forms may need blood cultures, PCR or tissue testing. Blood cultures miss many cases, and some heart valve infections never grow in culture.
Antibodies are common without illness. In one study cited in a 2019 review, 37.5% of healthy blood donors had them, so a positive result is hard to interpret alone.

Advocacy groups argue current tests miss many infections and results can vary between tests.

Treatment

Typical cat-scratch disease often clears up without antibiotics, though a clinician may prescribe one, such as azithromycin, for extensive lymph node swelling. Trench fever, Carrion’s disease, heart infections and eye or brain complications are treated with antibiotics chosen for that form. For the broader chronic symptoms, the 2020 study’s authors called for controlled treatment trials.

When to see a doctor

When to get help

See a provider for swollen lymph nodes after contact with a cat (MedlinePlus advice), a lasting fever after a cat scratch or bite, or any illness after a tick bite.
Get care promptly if you have a weakened immune system (for example HIV, chemotherapy or a transplant); Bartonella can be more serious.
Seek urgent care for sudden vision changes, confusion, seizures or a severe headache with fever.

Frequently asked questions

Can ticks transmit Bartonella to humans?

It has not been shown. CDC says there is no evidence that ticks spread Bartonella to people. Its DNA has been found in ticks, so some researchers and patient groups suspect a tick role, but this is not proven.

What are long-term Bartonella symptoms?

Documented long-term problems include heart valve infection and eye, brain or bone involvement; serious illness is more likely with a weakened immune system. Broader chronic symptom lists come mainly from case reports and small uncontrolled studies, so how often Bartonella causes them is uncertain.

Do stretch-mark-like lines mean I have Bartonella?

Not on their own. One small 2020 study described such lesions in people who tested positive, but it had no comparison group or skin biopsies, and causation was not confirmed. Show new skin changes to a clinician.

Bartonella and Lyme Disease: What Is Known and What Is Not