Infectious Disease Compendium

Cat scratch fever


A syndrome of fevers, regional lymphadenopathy, and a variety of non-specific symtoms: headache, myalgias etc.

Epidemiologic Risks

A cat scratch, while nice, is not a must; just being around the vermin may be enough.


B. henselae.

Serology is not perfect. To make the diagnosis need serology and PCR.

Biopsy of the lymph node will show stellate necrotizing granuloma.

Empiric Therapy

Trimethoprim/sulfamethoxazole OR azithromycin OR erythromycin OR doxycycline OR quinolone.

Specific Therapy

It's a self limited disease and the lymphadenopathy can take months to resolve, so response to antibiotics is hard to judge; 2 weeks po should suffice.

The majority of patients after a scratch will have symptoms (fatigue, arthralgias and myalgias), half of patients will seroconvert and maybe a quarter will have evidence of a blood stream infection (PubMed).


Can also cause an acute encephalitis and coma, that recovers spontaneously. I had one patient who had both of his girlfriends' cats put to death (the cats, not two girlfriends) after he had cat scratch encephalitis. Whether they are still together or not I do not know.


Cats really are vermin that serve no useful purpose but spread disease, or I have I said that before?

Last Update: 05/29/18.