Cat Scratch Fever in Cats & Humans: A Vet’s 2025 Guide to Bartonella Infection, Diagnosis & Prevention 🐱🩹
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Cat Scratch Fever in Cats & Humans: A Vet’s 2025 Guide to Bartonella Infection 🐱🩹
By Dr Duncan Houston, BVSc
🔍 What Is Cat Scratch Fever?
Cat scratch fever (cat scratch disease, CSD) is a bacterial infection caused by Bartonella henselae. Cats—typically kittens—harbor it asymptomatically, transmitted primarily via flea exposure, then passed to humans through scratches, bites, or licking open wounds :contentReference[oaicite:3]{index=3}.
⚠️ How Cats & Humans Catch It
- Fleas transmit Bartonella among cats—cats pick it up, carry the bacteria silently :contentReference[oaicite:4]{index=4}.
- Kittens and feral cats have higher infection rates—carry bacteria in saliva and claws :contentReference[oaicite:5]{index=5}.
- Humans get infected via cat scratches penetrating skin, bites, or cats licking open wounds :contentReference[oaicite:6]{index=6}.
🚩 Signs in Cats
Most infected cats show no symptoms. Occasionally they experience mild fever, lethargy, or lymph node swelling—but such signs are rare :contentReference[oaicite:7]{index=7}.
👀 Signs in Humans
- A raised blister or papule at infection site 3–14 days post-scratch :contentReference[oaicite:8]{index=8}.
- Painful swelling of nearby lymph nodes—axillary, cervical, or inguinal :contentReference[oaicite:9]{index=9}.
- Systemic symptoms: fever, fatigue, headache, malaise, mild body aches :contentReference[oaicite:10]{index=10}.
- Rare severe complications: encephalopathy, neuroretinitis, endocarditis, hepatosplenomegaly, ocular syndromes—mostly in immune‑compromised patients :contentReference[oaicite:11]{index=11}.
🔬 Diagnosis
- In cats: serious cases diagnosed via serology or PCR, along with blood culture/testing :contentReference[oaicite:12]{index=12}.
- In humans: diagnosis based on physical exam, lymph node findings, supported by antibody testing or PCR :contentReference[oaicite:13]{index=13}.
💊 Treatment
For Cats
Most healthy cats do not require treatment. In symptomatic or high-risk cats, doxycycline or quinolones (e.g., enrofloxacin) are used :contentReference[oaicite:14]{index=14}.
For Humans
Supportive care—warm compresses on lymph nodes, NSAIDs or acetaminophen, rest :contentReference[oaicite:15]{index=15}.
Antibiotics often prescribed in severe or prolonged cases (especially if immunocompromised):
- Azithromycin—short course may speed resolution of lymph nodes :contentReference[oaicite:16]{index=16}.
- In complex or atypical disease: doxycycline, ciprofloxacin, rifampin, TMP‑SMX or gentamicin may be used :contentReference[oaicite:17]{index=17}.
🔄 Outlook & Complications
- Most cases resolve in 2–4 months without meds :contentReference[oaicite:18]{index=18}.
- Complications (endo‑carditis, neuro‑retinitis, encephalopathy) are rare—but significant in immunocompromised or pediatric patients :contentReference[oaicite:19]{index=19}.
- Once infected, humans tend to develop immunity—but reinfection remains possible :contentReference[oaicite:20]{index=20}.
🛡️ Prevention Tips
- Keep cats indoors and use effective flea control—reduces Bartonella exposure :contentReference[oaicite:21]{index=21}.
- Trim claws and discourage rough play to minimize scratches :contentReference[oaicite:22]{index=22}.
- Clean scratches/bites immediately with soap and water; avoid cat licking at wounds :contentReference[oaicite:23]{index=23}.
- Wash hands after handling cats, especially kittens or stray cats :contentReference[oaicite:24]{index=24}.
- High-risk individuals (children, elders, immunocompromised) should not handle kittens or rescues :contentReference[oaicite:25]{index=25}.
📊 Quick Reference Table
| Aspect | Summary |
|---|---|
| Cause | Bartonella henselae, spread via fleas in cats, transmitted to humans via scratches/bites |
| Cat Signs | Usually silent; occasional fever, lymph swelling |
| Human Signs | Papule, tender lymphadenopathy, fever, fatigue; rare neurological or ocular involvement |
| Diagnosis | Cats: PCR/serology; Humans: exam + serology/PCR |
| Treatment | Supportive, heat compresses, antibiotics if severe |
| Prevention | Flea control, no rough play, hygiene, wound care |
| Outlook | Usually excellent; resolves within months; rare complications |