Diagnosis
A syndrome of fevers, regional lymphadenopathy, and a variety of non-specific symptoms: headache, myalgias, etc.
Epidemiologic Risks
A cat scratch, while nice, is not a must; just being around the vermin may be enough.
Microbiology
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 a 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 bloodstream infection (PubMed).
Pearls
It 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.
Rants
Cats really are vermin that serve no useful purpose but spread disease, or I have I said that before?
Last Update: 05/29/18.