Episode 228: Tickborne Illnesses

(https://coreem.net/podcast/episode-22...) Tickborne illnesses in the ED: attachment time, the rash, the smear, prophylaxis, & treatment. Hosts: Samantha Nakos, MD Brian Gilberti, MD https://media.blubrry.com/coreem/cont... Download (https://media.blubrry.com/coreem/cont...) Leave a Comment (https://coreem.net/podcast/episode-22...) Tags: Babesiosis (https://coreem.net/tag/babesiosis/) , Ehrlichiosis (https://coreem.net/tag/ehrlichiosis/) , Infectious Diseases (https://coreem.net/tag/infectious-dis...) , Lyme Disease (https://coreem.net/tag/lyme-disease/) , Tick-Borne Illnesses (https://coreem.net/tag/tick-borne-ill...) Podcast Video Show Notes Core EM Modular CME Course Maximize your commute with the new Core EM Modular CME Course, featuring the most essential content distilled from our top-rated podcast episodes. This course offers 12 audio-based modules packed with pearls! Information and link below.  Course Highlights: • Credit: 12.5 AMA PRA Category 1 Credits™ • Curriculum: Comprehensive coverage of Core Emergency Medicine,  with 12 modules spanning from Critical Care to Pediatrics. • Cost: • Free for NYU Learners • $250 for Non-NYU Learners Click Here to Register and Begin Module 1 (https://www.highmarksce.com/nyumc/Pla...) Lyme, Anaplasmosis, Ehrlichiosis & Babesiosis at a Glance LymeAnaplasmosisEhrlichiosisBabesiosisOrganismB. burgdorferi (spirochete)A. phagocytophilumE. chaffeensisB. microti (protozoan)VectorI. scapularisI. scapularisLone star tickI. scapularisAttachment time≥36–48 hCan be ＜24 hNo dataMostly ＞48 hKey clueEM rash↓WBC, ↓plt, ↑LFTs↓WBC, ↓plt, ↑LFTsHemolysis, ↓pltSmear—Morulae in neutrophilsMorulae in monocytesIntra-RBC parasites, Maltese crossConfirmClinical (EM)Smear, PCRSmear, PCRSmear, PCRTreatDoxy × 10–14 dDoxy × 10 dDoxy until ≥3 d afebrileAtovaquone + azithro × 7–10 d Background • Ixodes scapularis (deer tick) = primary US vector for Lyme, anaplasmosis, and babesiosis; I. pacificus on the West Coast. Ehrlichiosis → lone star tick (Amblyomma americanum), not the deer tick (CDC MMWR 2016 (https://doi.org/10.15585/mmwr.rr6502a1) ) • Why attachment time matters: B. burgdorferi lives in the tick midgut → multiplies and migrates to the salivary glands only after feeding starts → built-in delay • Single infected nymph: 0 of ~90 animals infected at 24 h, ~10% by 48 h, ~70% by 72 h (Eisen 2018 (https://doi.org/10.1016/j.ttbdis.2018...) ) • Anaplasma can transmit w/in 24 h. Babesia ≈ Lyme, not faster: earliest 36 h, mostly after 48 h. True speedster = Powassan virus (w/in 15 min). Attachment time by hx is often unreliable (IDSA Lyme 2020 (https://doi.org/10.1093/cid/ciaa1215) ) • Regional variation: US Lyme = B. burgdorferi; Europe = mostly B. afzelii, B. garinii → different clinical picture. Systemic sx w/ EM more common in the US: ~65% vs ~37% in Europe (IDSA Lyme 2020 (https://doi.org/10.1093/cid/ciaa1215) ) Lyme: The Rash and the Serology Erythema Migrans • EM in ~70–80% of infections; appears at the bite site 3–30 d post-bite (avg ~7 d) (CDC (https://www.cdc.gov/lyme/signs-sympto...) ) • Usually not a bull’s-eye → most early EM is uniformly red • Expanding erythematous patch + endemic area = Lyme until proven otherwise Serology • 2-tier: EIA or IFA → IgM/IgG Western blot (or modified 2-tier: 2 EIAs, no blot) • Early localized dz → often seronegative (as few as ~20% positive w/in 1 wk of noticing EM) → EM in an endemic area = clinical dx, per IDSA (IDSA Lyme 2020 (https://doi.org/10.1093/cid/ciaa1215) ) The Other Three: Labs and the Smear Babesiosis • Hunt for hemolytic anemia: ↓Hgb, ↑LDH, ↓haptoglobin, reticulocytosis; ↓plt and ↑LFTs common • Smear: intraerythrocytic parasites. Maltese cross (tetrad) = pathognomonic but infrequent; ring forms more common. PCR more sensitive than smear (IDSA Babesiosis 2020 (https://doi.org/10.1093/cid/ciaa1216) ) Anaplasmosis & Ehrlichiosis • Near-identical presentations. Classic triad: leukopenia, thrombocytopenia, transaminitis ...