Thread by @IUIDfellowship

#idboardreview 30 M from western 🇺🇸 visited Middle East where symptoms of recurrent fevers >102F, headaches, myalgia, chills started
3 wks ago. Peripheral blood smear shown. Dx? #medEd #idmedEd #IDtwitter

Rick borne relapsing fever #TBRF #Borrelia persica inspired by jcm.asm.org/content/58/6/e… @ASMicrobiology pic ref P&P Mandell

median incubation period of 7d (range 2-18d): fever x 3d (range 2-7d), alternating w/ afebrile periods lasting about 7d range 4-14d)
If untreated #TBRF can have up to 30 relapses of febrile illness (most pts w/2 relapses)
whereas louse-borne illness is usually has only 1 relapse

ticks are obligate blood feeders & spirochetes from a blood meal invade all tissues of tick w/in hrs. spirochetes can persist for yrs in tick salivary glands, facilitating transmission during short feeding pof 20 min. humans infected when saliva/excrement is released during feed

#TBRF spirochete changes surface antigen every 7d causing cyclic relapsing fever

#TBRF Spirochetes are seen in peripheral blood smears during febrile illness. Doxycycline or penicillin is effective treatment. Jarisch-Herxheimer reactions are common, and the patient should be observed in a clinic or hospital for about 3 hours after starting antibiotic therapy.

#TBRF Ref P&P Mandell