cat scratch disease

What Is It?
Cat Scratch Disease (CSD) is a bacterial infection caused by Bartonella henselae. It’s typically transmitted through the scratch or bite of a cat, especially kittens. It can also occur if cat saliva gets into an open wound or the eyes. While often mild, the infection can cause swollen lymph nodes, fever, and fatigue.

Why It Matters
Though usually not serious and self-resolving in healthy individuals, CSD can be more severe in young children, older adults, or people with weakened immune systems. In rare cases, the infection can spread to internal organs or the nervous system, requiring medical intervention. Awareness helps with prevention and early recognition of symptoms.

Key Facts (At a Glance)

  • Caused by: Bartonella henselae, a Gram-negative bacterium

  • Spread through: Scratches, bites, or licks from infected cats

  • Most common in children under 15

  • Peak incidence: Fall and winter (kitten season)

  • 40% of cats may carry the bacteria at some point

  • Cats generally don’t appear sick

How It Affects the Body
Once the bacteria enter the skin, they travel to nearby lymph nodes, usually within 3–10 days. This can cause:

  • Localized infection at the scratch site

  • Swollen, tender lymph nodes (often in armpits, neck, or groin)

  • In rare cases, it can affect the brain, liver, spleen, or heart (especially in immunocompromised individuals)

Common Symptoms

  • Small bump or blister at the scratch or bite site

  • Swollen lymph nodes near the area of the injury

  • Fever, fatigue, and headache

  • Occasionally, loss of appetite, joint pain, or rash

  • Rare complications include neuroretinitis, encephalopathy, or endocarditis

Risks & Side Effects

  • Most cases resolve without treatment

  • Severe complications are rare but possible, including:

    • Liver/spleen inflammation (bacillary angiomatosis)

    • Neurological issues like seizures or confusion

    • Eye infections

  • People with HIV/AIDS, organ transplants, or cancer are more likely to develop severe forms

Who Should Be Cautious

  • Immunocompromised individuals

  • People with open wounds or skin conditions exposed to cats

  • Cat owners with chronic illness or undergoing chemotherapy

  • Individuals exposed to young cats or kittens, which are more likely to carry the bacteria

When to See a Doctor
Seek medical attention if you or your child experience:

  • Painful or persistent swollen lymph nodes

  • Fever lasting more than 2–3 days

  • Symptoms that worsen instead of improving

  • Neurological symptoms like confusion or seizures

  • Eye problems, especially if a cat scratch is involved

Related Conditions / Interactions

  • Often confused with mononucleosis, tuberculosis, or lymphoma due to similar lymph node swelling

  • May worsen other chronic infections in immunosuppressed individuals

  • Can coexist with toxoplasmosis or fungal infections in at-risk patients

Last Updated: June 16, 2025