Cat Scratch Disease (often nick‑named “cat‑scratch fever”) is an infection caused by the bacterium Bartonella henselae. People usually catch it when a kitten or adult cat scratches, bites, or even licks broken skin. Flea dirt (flea droppings that stick to cats’ claws and teeth) carries the bacteria, so any activity that mixes flea dirt with a fresh scratch can pass the germ into the body. One to three weeks later, a small bump appears at the scratch site and the nearest lymph node becomes swollen and tender. In most healthy children and adults the illness is mild and fades on its own, but in some cases—especially in young children or people with weakened immune systems—the germ travels through the bloodstream and inflames the eyes, liver, spleen, brain, bones, or heart valves. CDCCleveland Clinic
The bacteria enter tiny skin blood vessels at the scratch site and hitch a ride inside our own white blood cells. They then migrate to the closest lymph node, triggering an immune “traffic jam”: lymphocytes, neutrophils, and macrophages crowd in, making the node swell, heat up, and hurt. If the immune system cannot wall off the infection quickly, organisms spill into the bloodstream and seed other organs, causing the “atypical” complications outlined below.
Main clinical “flavors” (types) of CSD
Classic, self‑limited lymphadenitis – The common form: a papule at the scratch site plus one or two swollen lymph nodes that clear over 2–8 weeks without treatment.
Parinaud’s oculoglandular syndrome – The germ lodges in the conjunctiva of one eye, causing redness, gritty pain, and nearby pre‑auricular node swelling.
Neuroretinitis – Inflammation of the optic nerve that blurs vision and may create a “macular star” of exudates; it is the most frequent serious eye complication. PubMed
Bacillary angiomatosis – Vascular skin or liver lesions that resemble raised red strawberries; almost always seen in people with advanced HIV/AIDS.
Hepatosplenic (granulomatous) CSD – Multiple tiny abscesses in the liver and spleen, producing fever of unknown origin and upper‑abdominal pain.
Osteomyelitis – Bones (often the vertebrae) become inflamed, leading to persistent pain and limping in children.
Encephalopathy – Sudden high fever, confusion, seizures, or coma caused by inflammation of brain tissue.
Endocarditis – Culture‑negative infection of heart valves; rare but life‑threatening.
Prolonged bacteremia without symptoms – Detected only by blood PCR in immunocompromised patients.
Miscellaneous atypical disease – Involvement of lungs, kidneys, or skin without obvious nodes; underscores the germ’s ability to reach almost any organ.
Each type shares the same root cause (spread of B. henselae), but body site and immune status determine the clinical picture.
Causes and risk factors
(Each numbered item is followed by a plain‑English paragraph.)
Direct cat scratch – The sharp tip of a claw drives bacteria‑laden flea dirt under the skin—still the number‑one route of infection.
Cat bite – Puncture wounds made by teeth can inject organisms deeper, making severe cases more likely.
Cat licking broken skin – Saliva mixed with flea dirt delivers germs into micro‑abrasions.
Contact with kittens – Young cats carry heavier flea burdens and higher blood levels of B. henselae, so playful kittens are a prime source.
Heavy flea infestation in the household – More fleas → more flea dirt → more bacteria on claws and teeth.
Owning multiple cats or working in a cattery/shelter – More cats means more opportunities for scratches and more potential carriers.
Stray or outdoor cats – They pick up fleas outdoors and are 2‑to‑3 times more likely to harbor the bacterium than strictly indoor pets.
Warm, humid climates – Fleas thrive in these conditions, so infection rates rise in subtropical regions.
Autumn and early winter – Seasonal spike parallels peak flea activity and peak adoption of kittens.
Children under 15 years – They play roughly with pets, get scratched more, and their immune systems have less previous exposure.
Immunocompromised state (HIV, cancer chemotherapy, organ transplant) – Fewer immune cells allow the bacteria to spread beyond lymph nodes.
Poor wound hygiene – Not washing a fresh scratch gives bacteria time to multiply before the skin closes.
Delaying medical evaluation – Persistent fever or node swelling can signal complicated disease that needs early antibiotics.
Veterinary or animal‑control professions – Daily handling of cats raises cumulative exposure risk.
Receiving a blood transfusion from an infected donor (extremely rare) – Documented in the medical literature but accounts for only isolated cases.
Common symptoms
Swollen, tender lymph nodes – Typically in the armpit, neck, or groin nearest the scratch; nodes feel like marble‑sized lumps that ache when pressed.
Red bump or blister at the scratch site – Appears within 3–5 days and may look like an insect bite before crusting over.
Low‑grade fever – A warm, slightly “off” feeling as body temperature hovers around 38 °C (100–101 °F).
General fatigue and weakness – The immune battle saps energy, making simple tasks feel exhausting.
Headache – Mild to moderate, often dull, worsens with the fever peaks.
Loss of appetite or mild weight loss – Swollen nodes and low‑grade fever blunt hunger signals.
Muscle or joint aches – Diffuse discomfort similar to a flu‑like soreness.
Rash or small pustules away from the scratch – Hypersensitivity skin reaction in some patients.
Sore throat – Enlarged cervical nodes may press on throat tissues and cause discomfort when swallowing.
Night sweats – Drenching sweats that interrupt sleep, a sign the body is fighting infection.
Diagnostic tests
A. Physical‑examination–based tests
Visual inspection of the inoculation papule – Doctors note its location, size, crust, and healing stage; confirming a compatible lesion boosts the clinical suspicion of CSD.
Systematic lymph‑node palpation – By rolling swollen nodes under the fingertips, the clinician assesses tenderness, mobility, and size; a single enlarged node near a scratch is typical for uncomplicated disease.
General organ examination – Feeling the abdomen for an enlarged spleen or liver flags possible visceral spread.
Fundoscopic eye exam – A beam of light through a dilated pupil may reveal optic‑nerve swelling or “macular star,” pointing to neuroretinitis.
B. Manual (bed‑side maneuvers and procedural) tests
Tender‑node pressure test – Gentle compression over a lymph node reproduces pain in CSD but is less intense in purely viral nodes; it helps separate bacterial from viral causes of adenitis.
Intra‑dermal skin (antigen) test – Historic but occasionally used in resource‑poor settings; a small amount of killed Bartonella extract injected under the skin causes a red bump in previously exposed patients.
Ocular motility check – Asking the patient to follow a finger in six directions detects pain or diplopia, hinting at ocular‑muscle inflammation in Parinaud’s syndrome.
C. Laboratory and pathological tests
Complete blood count (CBC) – May show mild anemia or an elevated white‑blood‑cell count, helping exclude leukemia or mononucleosis.
Erythrocyte sedimentation rate (ESR) or C‑reactive protein (CRP) – Both climb in inflammatory states; high values support bacterial involvement when fever origin is unclear.
Indirect immunofluorescence assay (IFA) for B. henselae IgM/IgG – A four‑fold rise in antibody titre between acute and convalescent sera confirms infection.
Polymerase‑chain‑reaction (PCR) for Bartonella DNA – Detects bacterial genes in blood, lymph‑node aspirate, or ocular fluid; useful when serology is negative early on.
Special culture of blood or tissue – Requires enriched agar and prolonged incubation (up to 21 days); positive isolates nail down the diagnosis but sensitivity is low.
Lymph‑node biopsy with Warthin–Starry silver stain – Microscope reveals necrotizing granulomas and tiny clumps of black‑stained bacilli, ruling out lymphoma or tuberculosis.
D. Electrodiagnostic tests
Electroencephalogram (EEG) – Measures brain‑wave patterns in patients with seizures or altered consciousness; diffuse slow waves suggest encephalopathy due to CSD.
Visual‑evoked potentials (VEP) – Electrodes on the scalp record the brain’s response to flashing lights; prolonged latency confirms optic‑nerve inflammation even before vision drops.
Nerve‑conduction studies (NCS) and electromyography (EMG) – Used when patients report tingling or weakness, helping distinguish a CSD‑related peripheral neuropathy from other causes.
E. Imaging tests
Ultrasound of lymph nodes – Shows whether a node is solid or contains pus; guides safe needle aspiration in suppurative cases.
Abdominal ultrasound or CT scan – Slices through the liver and spleen to reveal multiple bright nodules (granulomas) typical of hepatosplenic CSD.
Magnetic resonance imaging (MRI) of brain/orbit – High‑resolution images pick up optic‑nerve swelling, cerebral abscesses, or bone marrow edema without radiation exposure.
Positron‑emission tomography (PET‑CT) – When the fever source is mysterious, PET lights up metabolically active lesions throughout the body, steering biopsies to the right spot and differentiating infection from cancer.
Non‑Pharmacological Treatments
A. Exercise Therapies
Gentle Range‑of‑Motion (ROM) Exercises – Description: slow shoulder, elbow, and neck movements when upper‑body lymph nodes swell. Purpose: prevents joint stiffness and muscle wasting. Mechanism: keeps synovial fluid moving and boosts lymph drainage by muscle pumping.
Walking Programs – Description: 20–30 minutes of brisk walking, five days per week. Purpose: lowers systemic inflammation and improves mood. Mechanism: moderate aerobic activity stimulates anti‑inflammatory cytokines and lymph circulation.
Therapeutic Yoga (Restorative Style) – Description: gentle poses, props, and deep breathing. Purpose: reduces fatigue common after prolonged infection. Mechanism: parasympathetic activation dampens the stress‑hormone cortisol, aiding immune balance.
Aquatic Therapy – Description: slow exercises in waist‑deep warm water. Purpose: eases joint pain if nodes or surrounding tissues ache. Mechanism: buoyancy decreases joint load while hydrostatic pressure encourages lymph return.
Resistance Band Strengthening – Description: light bands for arm curls and rows 2–3 times weekly. Purpose: restores strength lost during illness. Mechanism: muscle contraction promotes lymph movement and releases growth factors helpful to recovery.
B. Mind–Body Therapies
Mindful Breathing (5‑4‑3‑2‑1 Method) – Description: focus on five breaths, four sensations, three sounds, etc. Purpose: counters anxiety that often spikes when nodes enlarge. Mechanism: lowers sympathetic output, reducing inflammatory signaling.
Guided Imagery – Description: listening to narrated healing scenarios. Purpose: improves pain tolerance during swollen‑node episodes. Mechanism: activates the brain’s descending pain‑modulation pathways to release natural endorphins.
Progressive Muscle Relaxation (PMR) – Description: tense–and‑release routine from toes to head. Purpose: relieves muscle guarding around sore regions. Mechanism: breaks pain‑spasm cycle and improves micro‑circulation.
Biofeedback‑Assisted Heart‑Rate Variability (HRV) Training – Description: wearable sensor plus phone app. Purpose: teaches control over stress reactions. Mechanism: higher HRV correlates with lower systemic inflammation markers.
Cognitive‑Behavioral Therapy (Brief, 4‑Session Course) – Description: structured talk therapy. Purpose: addresses illness anxiety and sleep issues. Mechanism: re‑frames catastrophic thoughts, which lowers the hypothalamic‑pituitary‑adrenal (HPA) axis overdrive.
C. Educational & Self‑Management Techniques
Lymph‑Friendly Skin‑Care Classes – Description: nurse‑led sessions on cleansing and moisturizing scratched areas. Purpose: prevents secondary bacterial entry. Mechanism: maintains skin barrier lipids and correct pH.
Cat Handling Workshops – Description: veterinary demos on safe play and nail trimming. Purpose: reduces new injuries. Mechanism: behavioral conditioning of both owner and pet decreases scratch events.
Sleep‑Hygiene Coaching – Description: blue‑light curfew, cool room, wind‑down ritual. Purpose: unlocks night‑time immune repair. Mechanism: promotes melatonin, a known immunomodulator.
Hydration Tracking with Smart Bottles – Description: reminders to drink 30–35 mL/kg/day. Purpose: keeps lymph fluid less viscous. Mechanism: maintains plasma volume and kidney toxin clearance.
Plant‑Rich Anti‑Inflammatory Diet Classes – Description: Mediterranean‑style cooking lessons. Purpose: lessens systemic inflammation load. Mechanism: polyphenols (e.g., quercetin) down‑regulate NF‑κB pathways linked to lymph swelling.
Manual Lymphatic Drainage (MLD) Self‑Massage Tutorials – Description: light, rhythmic strokes toward the collarbone. Purpose: speeds node deflation once infection wanes. Mechanism: increases superficial lymph capillary uptake.
Self‑Monitoring Logs (Symptom Diary) – Description: daily record of node size, fever, energy. Purpose: aids early detection of complications. Mechanism: pattern recognition alerts user to seek timely care.
Peer‑Support Groups (Online Forums) – Description: moderated digital communities. Purpose: cushions social isolation in prolonged cases. Mechanism: shared coping boosts oxytocin, linked to better immune outcomes.
Ergonomic Workplace Adjustments – Description: proper monitor height and keyboard reach. Purpose: prevents neck‑node compression by awkward posture. Mechanism: maintains cervical muscle tone and venous drainage.
Return‑to‑Activity Grading Sheets – Description: stepwise plan from rest to full sport. Purpose: prevents relapse of fatigue‑related symptoms. Mechanism: graded exposure lets mitochondria rebuild without overshooting oxidative stress.
Evidence‑Based Drugs for Cat Scratch Disease
Antibiotics shorten symptom duration and prevent severe organ involvement in high‑risk patients. The dosages below reflect adult norms; pediatric doses are weight‑based.
Azithromycin – Class: macrolide. Dose: 500 mg once day 1, then 250 mg daily days 2–5. Timing: start within 7 days of node swelling. Side Effects: mild diarrhea, metallic taste.
Doxycycline – Class: tetracycline. Dose: 100 mg every 12 h for 14–21 days. Side Effects: sun sensitivity, heart‑burn if taken lying down.
Rifampin (added to doxy for severe cases) – Class: rifamycin. Dose: 300 mg every 12 h for 14 days. Side Effects: orange urine/tears, drug‑interaction risk (CYP inducer).
Ciprofloxacin – Class: fluoroquinolone. Dose: 500 mg every 12 h for 10–14 days. Side Effects: tendon pain (rare), GI upset.
Trimethoprim–Sulfamethoxazole (TMP‑SMX) – Class: sulfonamide mix. Dose: 160/800 mg every 12 h for 10 days. Side Effects: rash in sulfa‑allergic, high potassium.
Gentamicin (IV for neuroretinitis) – Class: aminoglycoside. Dose: 3–5 mg/kg/day divided every 8 h for 5–7 days. Side Effects: kidney strain, ear toxicity—needs level checks.
Clarithromycin – Class: macrolide. Dose: 500 mg every 12 h for 7–10 days. Side Effects: bitter taste, QT prolongation.
Levofloxacin – Class: fluoroquinolone. Dose: 500 mg daily for 10 days. Side Effects: insomnia, rare glucose swings.
Linezolid (reserve for resistant strains) – Class: oxazolidinone. Dose: 600 mg every 12 h for 10–14 days. Side Effects: serotonin‑syndrome risk with SSRIs, optic neuropathy on long courses.
Azithromycin + Rifabutin combo (for HIV‑positive with bacillary angiomatosis) – Dose: azithro 500 mg/day plus rifabutin 300 mg/day for at least 3 months. Side Effects: neutropenia, red‑orange tears.
Dietary Molecular Supplements
These adjuncts help modulate immunity and tissue repair. Discuss with a clinician before use.
Vitamin C – Dose: 500 mg twice daily. Function: boosts collagen for skin healing. Mechanism: co‑factor in collagen cross‑linking and antioxidant mop‑up.
Zinc Gluconate – Dose: 30 mg elemental zinc daily for 2 weeks. Function: supports T‑cell activity. Mechanism: zinc fingers regulate DNA transcription in immune cells.
Omega‑3 Fish Oil (EPA + DHA) – Dose: 1,000 mg combined EPA/DHA daily. Function: anti‑inflammatory lipid mediator. Mechanism: converts to resolvins that dampen neutrophil over‑activation.
Quercetin – Dose: 500 mg daily with food. Function: flavonoid antioxidant that stabilizes mast cells. Mechanism: inhibits histamine release and NF‑κB.
Curcumin (Turmeric extract, 95 % curcuminoids + piperine) – Dose: 500 mg curcumin + 5 mg piperine twice daily. Function: down‑regulates inflammatory cytokines.
Echinacea Purpurea Extract – Dose: 300 mg three times daily for max 10 days. Function: mild immune stimulation early in infection. Mechanism: increases macrophage phagocytosis.
Probiotic Blend (L. rhamnosus + B. longum) – Dose: ≥10 billion CFU/day. Function: restores gut microbiome after antibiotics. Mechanism: competitive exclusion of pathogens and gut‑immune crosstalk.
N‑Acetyl Cysteine (NAC) – Dose: 600 mg twice daily. Function: glutathione precursor aiding detox and lung health.
Resveratrol – Dose: 200 mg/day. Function: sirtuin activator linked to anti‑inflammatory pathways.
Selenium (Selenomethionine) – Dose: 100 µg daily. Function: antioxidant enzyme (glutathione peroxidase) co‑factor critical for infection defense.
Regenerative or Stem‑Cell–Based Therapies
These remain experimental in CSD but show promise, particularly for rare chronic complications such as Bartonella‑related myocarditis or neuroretinitis.
Mesenchymal Stem Cell (MSC) Infusions – Dose: 1 × 10⁶ cells/kg IV, single session in trials. Function: immune modulation and tissue repair. Mechanism: MSCs home to inflamed sites, secreting anti‑inflammatory exosomes.
Exosome‑Rich Plasma (ERP) – Dose: 5 mL IV weekly × 4. Function: cell‑free regenerative signals. Mechanism: delivers micro‑RNAs that turn off excessive inflammation.
Umbilical Cord‑Derived MSC Sheets (Cardiac Patch) – Dose: surgically placed during myocarditis repair. Function: fosters new capillary growth.
Adipose‑Derived Stem‑Cell Gel for Ophthalmic Use – Dose: micro‑drop once in surgery. Function: retinal support in neuroretinitis.
Platelet‑Rich Plasma (PRP) Node Injection – Dose: 3 mL into residual suppurative node. Function: speeds remodeling after drainage.
Gene‑Edited MSCs Over‑Expressing IL‑10 – Dose: experimental 1 × 10⁶ cells/kg. Mechanism: augments anti‑inflammatory cytokine release; early animal data only.
Surgical Interventions
Needle Aspiration of Suppurative Lymph Nodes – Procedure: ultrasound‑guided puncture to remove pus. Benefits: instant pain relief, prevents skin rupture.
Excisional Lymphadenectomy – Procedure: complete removal of chronically enlarged node. Benefits: diagnostic clarity and symptom resolution when malignancy cannot be ruled out.
Laparoscopic Drainage of Hepatic/Splenic Abscesses – Procedure: keyhole surgery to evacuate pockets seen on CT. Benefits: preserves organ tissue, short recovery time.
Pars Plana Vitrectomy (Severe Neuroretinitis) – Procedure: removal of inflamed vitreous gel. Benefits: reduces vision‑threatening floaters and inflammation.
Pericardial Window for Cardiac Tamponade – Procedure: small chest incision to drain infected fluid around heart. Benefits: life‑saving pressure relief.
Prevention Strategies
Adopt cats over 1 year old (kittens scratch more).
Keep cats indoors to cut fleas and fights.
Monthly vet‑approved flea control.
Clip cat nails every 2 – 3 weeks.
Wash scratches right away with soap and water.
Avoid rough play—use toys, not hands.
Cover open cuts before handling pets.
Teach children gentle pet handling.
Pregnant or immunocompromised individuals: no new kittens.
Regular vet check‑ups and prompt treatment of feline illnesses.
When to See a Doctor
Fever above 38.5 °C lasting longer than 2 days after a cat injury.
Node bigger than a golf ball or that becomes red, hot, or fluctuant.
Eye pain or blurred vision, which may signal neuroretinitis.
Severe headache, confusion, or seizures (rare brain involvement).
Persistent fatigue or night sweats beyond 3 weeks.
Chest pain or shortness of breath pointing to heart inflammation.
Seek urgent care if any of these alarm signs appear—early antibiotics and imaging can prevent complications.
Things to Do & Things to Avoid
Do
Clean scratches promptly.
Finish the entire antibiotic course.
Keep a daily symptom diary.
Use insect repellents on cats.
Hydrate well (clear urine rule).
Avoid
6. Picking or squeezing swollen nodes—spreads infection.
7. Using leftover antibiotics without guidance.
8. Skipping meals; balanced nutrition speeds healing.
9. Letting cats lick open wounds.
10. DIY flea products not approved by vets—many are toxic.
Frequently Asked Questions
Is CSD contagious between people?
No—there is no solid evidence of human‑to‑human spread. Transmission is cat‑to‑human through scratches, bites, or saliva on broken skin.Will my swollen lymph node go away by itself?
About 80 % shrink within 2 to 6 months. Antibiotics hasten recovery and lower complication risk.Do all cats carry Bartonella henselae?
Estimates range 30–50 %, higher in kittens and stray cats with fleas. Indoor adult cats with flea control are far less likely to carry it.Can I keep my cat?
Yes. Good flea control, nail trimming, and gentle play keep both you and your pet safe.How soon after a scratch do symptoms start?
The typical incubation period is 3 to 14 days. A painless papule appears first, then lymph nodes swell.Why do my eyes hurt weeks later?
Neuroretinitis, an eye complication, can appear 2–8 weeks after the initial scratch. Seek ophthalmology review immediately.Is there a vaccine for CSD?
No human vaccine exists yet. Flea control on cats is the best preventive “shot.”Can CSD come back?
Reinfection is rare but possible if you get scratched again by an infected cat.Are pregnant people at higher risk?
Yes—the immune system shifts in pregnancy. Serious liver or spleen complications, though uncommon, occur more often in this group, so prompt medical care is vital.What tests confirm the disease?
Blood antibody tests, PCR for Bartonella DNA, node biopsy, or imaging (ultrasound, CT) depending on symptoms.Will antibiotics hurt my cat?
The medications listed are for humans. Never medicate your cat without veterinary advice; feline doses and drugs differ.Can I exercise while my nodes are swollen?
Light activity like walking is fine and may help, but avoid heavy lifting that strains sore areas.Do herbal remedies cure CSD?
No herb has proven curative power; some supplements support overall immunity, but they do not replace antibiotics when indicated.How long should I stay off work or school?
Many people can continue daily life if fever is controlled; avoid contact sports until lymph nodes settle to prevent rupture.What if lymph nodes stay enlarged for months?
Persistent lumps warrant re‑evaluation to rule out lymphoma, tuberculosis, or other causes. Your doctor may order biopsy or additional imaging.
Disclaimer: Each person’s journey is unique, treatment plan, life style, food habit, hormonal condition, immune system, chronic disease condition, geological location, weather and previous medical history is also unique. So always seek the best advice from a qualified medical professional or health care provider before trying any treatments to ensure to find out the best plan for you. This guide is for general information and educational purposes only. Regular check-ups and awareness can help to manage and prevent complications associated with these diseases conditions. If you or someone are suffering from this disease condition bookmark this website or share with someone who might find it useful! Boost your knowledge and stay ahead in your health journey. We always try to ensure that the content is regularly updated to reflect the latest medical research and treatment options. Thank you for giving your valuable time to read the article.
The article is written by Team RxHarun and reviewed by the Rx Editorial Board Members
Last Updated: July 15, 2025.
