Bartonella
Also called: Bartonellosis
Pathogen
Bartonella species (e.g. B. henselae, B. quintana)
Carried by
Associated with ticks, fleas, and cat scratches
Bartonella is a group of bacteria that infect the lining of blood vessels and red blood cells, which is part of why it can produce such wide-ranging, hard-to-pin-down symptoms. In the Lyme-literate community, Bartonella is considered one of the most common and clinically significant coinfections — and often one of the biggest reasons someone treated for 'just Lyme' doesn't fully recover. While mainstream medicine recognizes flea and cat-scratch transmission and considers tick transmission to humans unconfirmed, many clinicians who treat tick-borne illness see Bartonella regularly alongside Lyme and treat the two together.
If your Lyme treatment helped but left behind stubborn neuropsychiatric symptoms, foot pain, or those tell-tale skin striae, Bartonella is one of the first things an experienced clinician will consider.
Symptoms
- Neuropsychiatric symptoms — anxiety, irritability, rage, mood swings, OCD-like patterns
- Distinctive skin markings resembling stretch marks (often red or purple)
- Pain on the soles of the feet, especially in the morning
- Swollen glands, sore throats, low-grade fevers
- Burning or vibrating sensations, tremors
- Sudden anxiety or panic that feels 'chemical' rather than situational
Testing
Bartonella is notoriously hard to detect because it hides inside cells and circulates at low levels. Standard antibody tests miss many cases. Specialty testing that combines enrichment culture with PCR is the approach most trusted in the Lyme community for improving detection of this 'stealth' pathogen.
Labs often used in the Lyme community:
See our Testing Guide to understand your options.
Geography
Bartonella species are found nationwide. Because the recognized routes include fleas and cats in addition to ticks, exposure isn't limited to high-Lyme regions — one reason clinicians consider it worth evaluating in almost any suspected tick-borne case.
Explore the Where Ticks Live map to see what's carried in your region.
Treatment overview
Treatment is individualized and typically involves combination antibiotics chosen for the person's presentation, often over an extended period. There is no single standardized protocol, and Lyme-literate clinicians tailor therapy to symptoms and response. Herxheimer (die-off) reactions are common when treatment begins.
Frequently asked questions
Can ticks transmit Bartonella?
This is debated. Mainstream health agencies recognize fleas, lice, sand flies, and cat scratches/bites as established routes and consider human tick transmission unconfirmed. Bartonella DNA has been found in ticks, and many Lyme-literate clinicians treat it as a common tick-borne coinfection based on how often they see it alongside Lyme.
Why is Bartonella so hard to test for?
It lives inside cells and circulates at very low levels, so standard antibody tests frequently come back negative even when infection is present. Specialty labs use enrichment culture plus PCR to improve detection.