When Bartonella enters the body through a scratch or bite, nearby lymph nodes may become enlarged.
For example:
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A scratch on the hand may be followed by swelling around the elbow or armpit.
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A scratch on the arm may lead to enlarged lymph nodes near the armpit.
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A scratch on the leg may be followed by swelling in the groin.
The affected lymph nodes may feel tender or painful.
They often become noticeable one to three weeks after the initial scratch, although timing varies.
In many people, the swelling gradually improves over several weeks.
However, persistent or unusually large lymph nodes should be evaluated.
Other infections and medical conditions can also cause swollen lymph nodes, so self-diagnosis is not appropriate.
6. Fever, Fatigue, and General Body Discomfort
Cat scratch disease can produce symptoms that resemble a mild viral illness.
Some individuals develop a low-grade fever, fatigue, headache, and general discomfort.
These symptoms may appear alongside swollen lymph nodes.
The immune system is responding to the bacterial infection, producing inflammatory signals that can affect the entire body.
Some people experience reduced appetite or feel unusually tired.
In otherwise healthy individuals, these symptoms often resolve without major complications.
However, persistent fever, worsening fatigue, or symptoms that continue to progress should be evaluated.
A doctor may consider the history of cat exposure, the appearance of the skin lesion, lymph node changes, and laboratory testing.
7. Can Bartonella Affect the Heart?
One of the more serious complications associated with Bartonella infection is infective endocarditis.
This is an infection involving the inner lining of the heart or its valves.
Bartonella species are recognized causes of culture-negative endocarditis, meaning that standard blood cultures may fail to identify the organism.
Bartonella endocarditis is uncommon, but it can be serious.
Symptoms may include:
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Persistent or recurring fever.
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Night sweats.
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Unexplained weight loss.
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Severe fatigue.
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Shortness of breath.
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New or changing heart murmurs.
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Signs of heart failure.
People with certain pre-existing heart valve abnormalities, prosthetic valves, or other cardiac risk factors may require particular attention.
However, sleeping with a cat does not mean that someone will develop a heart infection.
Endocarditis is a rare complication and should not be presented as an expected consequence of pet ownership.
If a person develops persistent fever or unexplained cardiac symptoms, prompt medical evaluation is essential.
8. Can Cat Scratch Disease Affect the Eyes?
In some cases, Bartonella infection can involve the eyes.
One recognized complication is Parinaud oculoglandular syndrome.
This condition may cause inflammation of the conjunctiva, the thin membrane covering the front of the eye and inner eyelids.
Symptoms can include:
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Redness in one eye.
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Eye irritation.
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Swelling around the eyelid.
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Discomfort.
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Enlarged lymph nodes near the ear or jaw.
Another possible complication is neuroretinitis.
This involves inflammation affecting the retina and optic nerve.
People may experience blurred vision, changes in visual clarity, or other visual disturbances.
Eye involvement is uncommon but important because vision problems require prompt assessment.
Anyone experiencing sudden vision changes, significant eye pain, or severe redness should seek urgent medical attention.
9. Rare Neurological Complications
Although most cases of cat scratch disease remain relatively mild, Bartonella infection can occasionally involve the nervous system.
One uncommon complication is encephalopathy, a condition involving altered brain function.
Possible symptoms include confusion, severe headache, seizures, or changes in consciousness.
Other neurological complications have also been reported.
These manifestations are rare and should not cause unnecessary fear among ordinary cat owners.
However, sudden confusion, seizures, severe headache, or other acute neurological symptoms require emergency medical care regardless of the suspected cause.
10. People With Weakened Immune Systems May Face Greater Risks
Most healthy individuals recover from uncomplicated cat scratch disease.
However, certain people may be more vulnerable to severe or unusual infections.
These include individuals with:
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Advanced HIV infection.
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Organ transplants.
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Certain blood cancers.
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Conditions requiring immunosuppressive medication.
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Other significant immune system disorders.
One important Bartonella-related condition is bacillary angiomatosis.
This is an uncommon vascular skin disorder that can occur in people with substantial immune suppression.
It may cause red, purple, or blood-vessel-like skin lesions that can resemble other conditions.
Bartonella can also involve internal organs in severely immunocompromised individuals.
For these patients, preventive measures are particularly important.
They should discuss pet-related risks with their healthcare team rather than automatically giving up their animals.
With appropriate veterinary care and hygiene, many people with weakened immune systems can continue enjoying safe relationships with pets.
11. What About Toxoplasmosis From Sleeping With Cats?
Another infection frequently discussed in connection with cats is toxoplasmosis.
It is caused by a parasite called Toxoplasma gondii.
Cats are the definitive hosts of this parasite, meaning that sexual reproduction occurs in felines.
Infected cats may shed parasite oocysts in their feces for a limited period.
Humans can become infected through several routes, including:
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Accidentally ingesting contaminated material from cat feces.
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Handling contaminated soil.
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Eating undercooked meat containing tissue cysts.
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Consuming contaminated food or water.
Simply sleeping beside a cat is not considered a typical route of toxoplasmosis transmission.
A cat's fur is also not generally the primary source of infection.
The greatest concerns often involve contaminated litter, soil, and food.
Toxoplasmosis is particularly important during pregnancy because a new infection can sometimes affect the developing fetus.
People with weakened immune systems may also experience more serious complications.
Pregnant individuals and immunocompromised people should discuss appropriate precautions with their healthcare professionals.
12. Ringworm: A Fungal Infection That Can Spread From Cats
Ringworm is another condition worth understanding.
Despite its name, ringworm is not caused by a worm.
It is a fungal infection affecting the skin, hair, or nails.
Cats can carry dermatophyte fungi, particularly Microsporum canis.
Some infected cats develop visible hair loss, scaling, or circular patches on their skin.
Others may carry the fungus without obvious symptoms.
Humans can become infected through direct contact with an infected animal or contaminated objects.
Symptoms in people may include:
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Circular or ring-shaped skin rashes.
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Redness.
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Itching.
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Scaling.
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Areas of hair loss when the scalp is affected.
Ringworm is generally treatable with antifungal medication.
Veterinary examination is important because an infected cat may require treatment to prevent continued transmission.
Regular cleaning of bedding, grooming equipment, and frequently used surfaces can also help reduce environmental contamination.
13. Fleas: A Small Parasite With Important Health Implications
Fleas are more than a nuisance.
They can cause itching, allergic skin reactions, and discomfort in cats and humans.
They are also important in the transmission cycle of Bartonella among cats.
When infected fleas feed on a cat, bacteria may circulate in the animal's bloodstream.
Flea feces can then contaminate the cat's fur or environment.
If this material enters broken human skin, transmission may occur.
Effective flea prevention therefore plays a major role in reducing Bartonella exposure.
Veterinarians can recommend appropriate flea-control products based on the cat's age, health, and lifestyle.
Never use a flea product intended for dogs on a cat without veterinary guidance.
Some ingredients found in dog flea treatments, particularly certain concentrated pyrethroid products, can be extremely toxic to cats.
14. How Can You Reduce the Risks While Still Sleeping With Your Cat?
The good news is that most people do not need to stop sleeping with their cats simply because infections are possible.
A few practical habits can significantly improve hygiene and reduce exposure.
Keep flea prevention up to date.