Bartonella and Cat Scratch Fever 🐱🦠

By Dr Duncan Houston, BVSc

Cat scratch fever is more than just a quirky name—it’s a real bacterial infection caused by Bartonella henselae. This disease can affect both cats and humans and is primarily spread through fleas. In this guide, Dr Duncan Houston explains how Bartonella spreads, how it affects pets and people, and what to do if you’re concerned. 🩺

🔬 What Is Bartonella?

Bartonella is a genus of bacteria with over 24 known species. Cats commonly harbor five species, with Bartonella henselae being the most well-studied. Transmission is primarily via fleas—not bites or grooming. 🦟

How Cats Spread It:

• 🐾 Cat has fleas → flea dirt accumulates on claws
• 😾 Cat scratches itself → bacteria enters under nails
• 🧍 Cat scratches person or another cat → infection risk

😷 Cat Scratch Fever in Humans

In healthy individuals, Bartonella infection causes localized symptoms:

• 📍 Red bump (papule) at scratch site
• 🦠 Swollen lymph nodes (2–3 weeks after scratch)
• 🌡️ Fever, fatigue—usually self-limiting

🚨 In High-Risk Individuals:

If the person is immunocompromised (young, elderly, ill), Bartonella can cause more serious issues:

• 🧠 Encephalitis
• 🫀 Endocarditis (heart valve infection)
• 🧬 Splenomegaly (enlarged spleen)

🐱 Do Infected Cats Get Sick?

Most infected cats show no signs of illness and act as asymptomatic carriers. However, in rare cases, Bartonella may cause:

• 🌡️ Fever
• 👁️ Deep eye inflammation
• 🦴 Lymph node swelling
• 🦠 Endocarditis
• ❗ Reproductive failure (rare)

📊 Prevalence & Risk Factors

In some warm, humid areas, up to 40% of cats may carry Bartonella. Risk increases in:

• 🌴 Flea-prone climates
• 🏚️ Shelter or outdoor cats
• 🐾 Cats without strict flea control

🔬 Can Cats Transmit to Other Cats?

Direct cat-to-cat transmission is unlikely. Grooming, mating, or sharing food/litter does not seem to spread the infection. Fleas are the true culprits. 🦟

🐶 What About Dogs?

Yes—dogs can also be infected, primarily with Bartonella vinsonii. Ticks may be an additional vector for dogs. Many dogs infected with Bartonella also have other tick-borne diseases. 🐕🧬

🧪 Should I Test My Cat?

Routine testing is not recommended unless:

• 💉 Your cat is a blood donor
• 😿 Your cat is symptomatic and Bartonella is suspected
• 🏠 A human in the household is immunocompromised

Available Tests:

• 🧫 ELISA, IFA, Western Blot – detect antibodies
• 🧬 PCR – detects Bartonella DNA (may miss intermittent infections)
• 🧪 Culture – most reliable, but must be repeated

💊 Treatment for Cats

• 💊 Antibiotics: doxycycline, azithromycin, amoxicillin-clavulanate, fluoroquinolones
• 🕒 Duration: minimum 3 weeks
• ⚠️ Resistance to antibiotics is common; treatment is only recommended for symptomatic cats or if an immunocompromised person is in the household

🛡️ Prevention Tips (CDC + EABCD)

• 🐾 Adopt only healthy cats >1 year old
• 🚫 Avoid shelters/multi-cat homes if immunocompromised
• 🏡 Keep cats indoors
• 🧽 Maintain strict flea control
• ✂️ Trim claws regularly
• 🧼 Wash all scratches promptly

💊 Should We Use Prophylactic Treatment?

No. Preventive drug use is not recommended after a cat scratch—even if infection is suspected. Just clean the area and monitor. 🧴

📱 Ask A Vet App Support

Worried about Bartonella exposure or immune safety at home? The Ask A Vet app can help:

• 📋 Discuss flea protocols and infection prevention
• 🧪 Upload test results for interpretation
• 💬 Chat with licensed vets about symptoms or risk
• 📅 Monitor treatment progress for Bartonella-positive cats

🏁 Final Takeaway

Bartonella is common in cats, but human disease is preventable with proper flea control and hygiene. Don’t panic if your cat tests positive—it rarely causes illness in cats or people. Use preventive tips, maintain flea protection, and consult your vet or the Ask A Vet app if someone in your home is immunocompromised. 🐱🦠❤️