Rocky Mountain Spotted Fever (RMSF)

RMSF is the most common fatal rickettsial illness in the United States.

Overall hospitalization rates are noted be at 23.4% based on aggregated reviews of case reports (Openshaw 2010.

Case fatality rate is estimated to be 5-10% overall (Biggs 2016). If treatment is delayed, case-fatality rates of 40-50% have been described for patients treated on day 8 or 9 of their illness.

Case fatality rate is highest in those over the age of 70 (Amsden 2005).

Without treatment, the case fatality rate is over 25% (Lacz 2006).

Citation: Muhammad Durrani, “Emerging Tick-Borne Illnesses: Not Just Lyme Disease Part 4 RMSF”, REBEL EM blog, November 5, 2020. Available at:

The CFR for untreated RMSF surprised me.

And yet another reason besides bears to stay out of the woods.

Remind me to tell some of my favorite tick stories when we can all gather unmasked to enjoy some food and drink.

Office Derm: Can You Make the Diagnosis?

A previously healthy 27 year old male comes into your office complaining of headache, muscle pain, and a rash consisting of numerous non-blanching macules on his forearms, wrists, feet, and ankles. The patient tells you that just over a week ago he went on a camping trip in Oklahoma with some of his college buddies and thinks that he may have been bitten by something.

via Office Derm: Can You Make the Diagnosis?.

Take the test.  It’s fun.  Keyword – bitten.

You should be able to make the correct diagnosis.