Caused by a rickettsial bacteria and transmitted by certain ticks, RMSF occurs in tick season, April to September. It’s almost only found in high-risk areas — you’ll never guess. North Carolina usually leads the list, followed by OK, TN, AR, MO, northern counties of MS and AL, southeast VA, & maybe the MD Chesapeake Peninsula (every county in the country has its own statistics). There’s a new focus on Arizona tribal lands, & northern Mexico. RMSF is very rare in CO & the Rockies! Half of patients have noticed a tick bite, which means 50% haven’t.
Symptoms are mild at first, but include fever & headache. After the 3rd or 4th day it can cause Shock and kill. No tests are useful. We treat based on symptoms alone, in the right place at the right time.
The “spots” appear later, sometimes too late. They’re called “petechiae,” — tiny reddish-purple spots which by definition don’t blanche (“blanche” = turn white for a split second when you push on them, then resume their color). However, in their first few hours, soon-to-be-petechiae actually do blanche. We must never dismiss very new, discrete, blanching spots in a patient with fever. If ER clinicians ignore the concern, we wait around a few more hours, for any petechiae to develop that don’t blanche. If the spots go away first, they won’t be petechiae.
We treat with doxycycline, a type of tetracycline antibiotic. It’s famous for being contraindicated (forbidden) in children <8 and pregnant women, due to tooth discoloration, even though we’ve known for over 20 years that there’s no good proof of this. If someone has fever & headache in the above areas, in the above months, child or not, pregnant or not, the CDC and American Academy of Pediatrics insist on doxycycline. You should too!