Bartonellosis: A Comprehensive Guide
Medically reviewed by Andre Stone | MD, University of Pittsburgh School of Medicine on April 1st, 2026.
Published on April 1st, 2026. Updated on August 24th, 2026.
Key Takeaways
Bartonellosis is a bacterial infection caused by Bartonella species that can affect multiple organ systems
Cat scratch disease is the most common form, typically transmitted through cat scratches or bites
Symptoms range from mild lymph node swelling to severe complications affecting the heart, brain, and other organs
Early diagnosis and appropriate management can prevent serious complications; antibiotics are used when clinically indicated.
People with weakened immune systems face higher risks of severe disease and complications
Overview
Bartonellosis refers to a group of bacterial infections caused by Bartonella species. These gram-negative bacteria can infect humans through various routes, most commonly through animal scratches, bites, or insect vectors like fleas and sandflies.
The most well-known form is cat scratch disease (CSD), one of several infections caused by Bartonella species. Bartonella infections can also cause conditions such as Parinaud oculoglandular syndrome and, less commonly, infections involving the heart, nervous system, eyes, liver, spleen, or blood vessels. The bacteria primarily target blood vessels and can spread throughout the body, affecting the lymph nodes, heart, brain, eyes, and other organs.
Bartonella infections occur worldwide. The true number of US cases is uncertain because surveillance and reporting vary, and many mild cases may never be diagnosed. Young children and immunocompromised individuals are at higher risk for severe complications. Early recognition and appropriate treatment can significantly improve outcomes and prevent long-term health problems.
Cat-scratch disease gets its name from its association with cat scratches and bites, but it is only one form of bartonellosis. Scientists discovered the bacteria in the 1980s and have been learning about it ever since. Understanding how it spreads helps people protect themselves and their families from this preventable infection.
Symptoms & Signs
Bartonellosis symptoms vary widely depending on the bacterial species involved, the patient's immune status, and which organs are affected. In cat-scratch disease, a bump may appear at the exposure site within several days, while swollen lymph nodes often develop one to three weeks later. Timing differs among Bartonella infections.
Primary Symptoms
Swollen lymph nodes, especially near the site of animal contact, that may be tender or painful
A mild fever that may persist for several days or, in some cases, longer
Fatigue and general feeling of being unwell, similar to flu-like symptoms
Red, raised bump or pustule at the scratch or bite site that appears 3-10 days after injury
Headache and muscle aches can occur. Seek medical advice if symptoms are severe, worsening, or accompanied by other concerning signs.
Many people compare the early symptoms to having a mild cold or flu. The swollen lymph nodes are usually the most noticeable sign and may stay enlarged for weeks. Some people feel tired for longer than others, depending on how strong their immune system is.
When to Seek Care
Contact a healthcare provider if you develop persistent swollen lymph nodes after animal contact, especially cats. Seek immediate medical attention for high fever above 102°F, severe headaches, vision problems, or neurological symptoms like confusion or seizures.
If your symptoms don't improve after two weeks, call your doctor for an evaluation. Don't ignore signs that are getting worse instead of better. Tell your doctor if you had contact with a cat, since this information helps them diagnose your condition faster.
When to Seek Immediate Care
Seek immediate medical attention for a fever above 102°F, a severe headache, vision changes, confusion, seizures, difficulty speaking, or other neurological symptoms.
Causes & Risk Factors
Age
Cat-scratch disease is diagnosed most often in children and adolescents. Older adults and people with certain health conditions may be more vulnerable to complications, although risk varies by the type of infection.
Genetics
Immunocompromised individuals face severe complications and prolonged illness
Lifestyle
Cat ownership, veterinary work, and outdoor activities increase exposure risk
Other Conditions
HIV/AIDS, cancer treatment, and organ transplant recipients have higher complication rates
Continue Learning
Related articles you might find helpful
Diagnosis
Medical History & Physical Examination
Your doctor will ask about recent contact with cats, other animals, or insect bites. They'll examine the scratch or bite site and check for swollen lymph nodes throughout your body. The physical exam focuses on identifying characteristic signs like regional lymphadenopathy and skin lesions.
Healthcare providers also assess your immune status and review any medications that might affect your ability to fight infections. They'll look for uncommon complications affecting the eyes, heart, nervous system, liver, spleen, or other organs.
Diagnostic Testing
Blood tests including complete blood count, inflammatory markers, and specific Bartonella antibody levels
Polymerase chain reaction (PCR) testing to detect bacterial DNA in blood or tissue samples
Lymph node biopsy in cases with persistent swelling or when cancer is suspected
Imaging studies like ultrasound or CT scans to evaluate internal organ involvement
Specialized testing for eye involvement or neurological complications when symptoms suggest systemic spread
Get Infection Relief Today
Learn More
Treatment Options
Treatment focuses on eliminating the bacterial infection and managing symptoms to prevent complications. Most otherwise healthy people with uncomplicated cat-scratch disease recover without antibiotics. People with weakened immune systems or signs of organ involvement need prompt medical evaluation, and treatment should be tailored to the specific infection and complication.
Conservative Treatments
Warm compresses applied to swollen lymph nodes for 15-20 minutes several times daily
Over-the-counter pain relievers like ibuprofen or acetaminophen for comfort and fever reduction
Rest and adequate hydration to support the immune system's natural healing process
Gentle wound care with soap and water for scratch sites, avoiding harsh antiseptics that delay healing
Many people get better on their own without medicine if their immune system is strong. Keeping the area clean prevents other infections from developing on top of the Bartonella infection. Your body works hard to fight the bacteria, so giving it rest helps it heal faster.
Advanced Treatments
When antibiotics are indicated, the drug or combination and treatment length depend on the Bartonella species and the organs involved. A clinician may use azithromycin for uncomplicated cat-scratch disease, while serious infections often require different combinations and longer treatment.
Intravenous antibiotics for severe systemic infections or complications affecting the heart or brain
A clinician may use needle aspiration to relieve a severely painful or pus-filled lymph node. Routine incision and surgical drainage are generally avoided because they can lead to persistent drainage or scarring.
Complications such as endocarditis require specialist care, prolonged combination antibiotic treatment, and monitoring tailored to the patient's heart condition.
Your doctor will choose the right antibiotic based on how sick you are and your medical history. It's important to take the full dose of antibiotics, even if you feel better before finishing. Some people need antibiotics through an IV in the hospital if their infection is very serious.
Living with the Condition
Daily Management Strategies
Monitor your symptoms closely and keep a journal of fever patterns, lymph node changes, and energy levels. Apply warm, moist compresses to swollen areas for comfort and to promote healing. Take medications as prescribed, even if you start feeling better before finishing the full course.
Stay hydrated and maintain good nutrition to support your immune system's recovery efforts. Avoid strenuous activities if you feel fatigued, but gentle movement can help prevent stiffness and promote circulation. Keep follow-up appointments with your healthcare provider to monitor progress and catch any complications early.
Drinking plenty of water and eating healthy foods gives your body the energy it needs to fight the infection. You should rest more than usual during the first few weeks of illness. Having family members help with chores lets you focus on getting better.
Exercise & Movement
Light walking and stretching are generally safe during recovery, but avoid intense exercise until your doctor clears you. Swimming should be postponed if you have open wounds or active skin lesions. Listen to your body and rest when needed, as pushing too hard can slow healing and worsen symptoms.
Gentle activities like slow walks help keep your muscles strong while you recover. You can return to your normal exercise routine once your doctor says you're ready. Getting back to sports or gym workouts too quickly can set back your recovery progress.
Prevention
Avoid rough play with cats and wash hands immediately after handling any feline
Keep cats indoors when possible and maintain regular flea control treatments
Clean cat scratches and bites promptly with soap and running water. Ask a healthcare professional whether additional wound care is needed, especially for a deep bite or signs of infection.
Trim cats' nails carefully and avoid rough play, especially for people at higher risk of severe infection. Do not declaw a cat solely to prevent Bartonella infection; discuss safer handling and flea control with a veterinarian and healthcare professional.
Seek veterinary care for sick cats and maintain regular health checkups for pets
Use insect repellent in areas where sandflies are common, especially in tropical regions
Manage any underlying health conditions and follow your healthcare professional's advice, particularly if your immune system is weakened.
The best way to prevent bartonellosis is to avoid getting scratched by cats in the first place. Teaching children to be gentle with cats and not pull their tails or ears helps prevent scratches. If you do get scratched, wash it right away with soap and water to reduce infection risk.
Keeping your cat's nails trimmed short makes scratches less deep and damaging. Regular flea control is important because cat fleas spread B. henselae between cats. Whether fleas commonly transmit this species directly to people remains uncertain. If you have a weak immune system, ask your doctor if you should limit contact with cats.
Frequently Asked Questions
No, bartonellosis does not spread between people through casual contact. Transmission depends on the Bartonella species. Cat-scratch disease usually follows a scratch contaminated with flea dirt and can also follow a bite; other species are transmitted by vectors such as body lice or sand flies. Person-to-person spread is uncommon, but rare non-casual routes have been reported.
Most otherwise healthy people with uncomplicated cat-scratch disease recover without treatment, although symptoms and swollen lymph nodes can take weeks to several months to resolve.
Repeat Bartonella infection may be possible, particularly with a different species or strain, but the duration and degree of immunity after infection are not well defined.
Information about Bartonella infection during pregnancy is limited. Pregnant people with a possible exposure and compatible symptoms should contact a healthcare professional for individualized advice and should use routine precautions to avoid cat scratches, bites, and fleas.
Indoor cats have lower infection rates than outdoor cats, but they can still carry bartonella bacteria. Kittens and cats with flea problems pose higher transmission risks regardless of their living environment.
Still have questions?
Consult with a healthcare professional for personalized advice.