Lyme / Ehrlichia Flashcards
Location of Lyme / Ehrlichia
•Mainly found in northeast coast, WI, and MN
Lyme Disease Cause Population Season Reservoir
- Borrelia burgdorferi
- Bimodal distribution: kids 5-14 and adults 55-70
- Mainly spring / summer
- Normally lives in mice / squirrels
Transmission of Lyme Disease NE / midwest vector Pacific US vector Lifecycle Tick feeding / timeline
- NE and Midwest: blacklegged tick (aka deer tick) Ixodes scapularis
- Pacific US: pacific black-legged tick Ixodes pacificus
- Lifecycle (takes 2 years): eggs → larvae → nymphs → adults → eggs
- Need a blood meal to progress b/w each meal
- Larvae usually acquire B burgdorferi from birds or mice. Infected for life.
- Nymphs are the most likely to transmit disease to humans
- Tick takes up blood and spits up excess water back into you, which transmits the bacteria. Also poops on you, which also may get rubbed in.
- Tick’s saliva has anticoagulant and anti-inflammatory components to allow for continued feeding.
- Tick usually needs to be attached for 36-72 hrs for transmission to occur
Lyme AB prophylaxis criteria (4)
Need to meet all 4 criteria to use doxycycline:
•Attached tick can be identified as nymph or adult I scapularis and has been present > 36h
•Within 72h of removal
•Local tick infection rate > 20%
•No contraindications
Stage 1 Lyme Timeline Sxs (local and systemic) What does high fever suggest? Diagnosis
- Early localized infection (usually 7-14 days)
- Sxs: Erythema migrans in 75% of pxs. Slowly expands outward. Center may become eccymotic / necrotic. Common on thigh, butt, groin, and axilla.
- Systemic sxs in 80% of people: mild fever, chills, malaise, headache, joint / muscle pain.
- High fever suggests coinfection w/ babesiosis
- Diagnosis – clinical features + exposure risk. Abs are not positive yet.
Stage 2 Lyme
Timeline
Sxs (7)
- Early disseminated (days / weeks after bite)
- Multiple erythema migrans lesions
- Migratory pain / joint pain (60%)
- Neuro – Lyme meningitis (aseptic), facial nerve paralysis, radicular neuropathy (15%)
- Lyme Carditis
- Ocular, including ptosis
What 2 things should you suspect w/ Bell’s Palsy?
Bell’s Palsy: look for herpes and look for Lyme
Lyme meningitis What stage? Labs Diagnosis Sxs (5) Treatment
- Stage 2
- Lymphocytic pleocytosis (100 cells), normal glucose, high protein
- Lyme specific Ab is present in CSF
- Headache, neck stiffness / pain, CN VII palsy, irritability, sleep probs
- Tx w/ ceftriaxone b/c it penetrates the CNS well
Lyme carditis What stage? Clinical manifestations (3) How long does it last? Treatment
- Stage 2
- Fluctuating degress of AV block (8%). May use temporary pacemaker. Risk of myocarditis.
- Fatigue / lightheadedness
- Usually lasts days – 6 weeks
- Tx w/ ceftriaxone in hospital and then oral therapy at home
Stage 3 Lyme
Timeline
Sxs (6)
- Late disseminated (months after bite)
- Lyme Arthritis – Intermittent or chronic attacks of large joint arthritis. Knee is most common. Inflammation.
- Encephalopathy – cognition, sleep, personality
- Polyradiculopathy, spastic paresis, ataxia
- Fatigue
Lyme arthritis
What stage?
Diagnosis
Treatment
- Stage 3
- Lyme PCR of synovial fluid can help diagnose
- Tx – oral AB’s. Ceftriaxone if recurrent. If persistent despite AB’s, consider an autoimmune disorder
Post-Lyme Disease Syndrome (aka Chronic Lyme Disease)
Timeline
Sxs (4)
Treatment
- Unexplained sxs > 6 months after AB’s
- Fatigue, myalgias, arthralgias w/o arthritis, cognition / memory problems
- No benefit from prolonged AB use
2 step testing for Lyme
ELISA then Westernblot if ELISA was positive
General treatment for Lyme
Oral DOC / alternatives
IV drug / uses
•Oral: doxycycline is DOC. Contraindicated during pregnancy, lactation, or kids
Causes and general characteristics of Ehrlichiosis
Location in body
Anaplasma and Ehrlichia are small gram neg obligate intracellular bacteria w/ a tropism for WBCs. Common in bone marrow and RE system.
Human granulocytic anaplasmosis (HGA) Cause / cell distribution Vector Animal reservoir Histologic finding
- Anaplasma phagocytophilum. Found in granulocytes.
- Vector: I scapularis / pacificus (same ticks as Lyme, so distribution / risks are the same)
- Animal reservoir is white tailed deer
- Histo: Morulae are seen in 20-80% of pxs. These are cytoplasmic vacuoles where bacteria replicate.
Human monocytotrophic ehrlichiosis (HME) Cause / cell distribution Vector / location Animal reservoir Comparison to HGA (human granulocytic anaplasmosis)
- Ehrlichia chaffeensis. Found in monocytes.
- Vector: Lone star tick. Mainly found in south central / SE US
- Animal reservoir is white tailed deer
- Comparison: causes more CNS disease and has higher mortality rate than HGA
Sxs of ehrlichiosis 100% (4) Less than 50% (4) Others Severe cases
- Fever, headache, myalgias, malaise (100%)
* NVD, arthralgias, cough, confusion (
Labs for erhlichiosis (5)
- High ALT and AST (by day 1)
- Low platelets (by days 1-3)
- Low WBC/lymphopenia (by day 3)
- Anemia (slow decline over day 7-14)
- High creatinine (24-70%)
Diagnosing ehrlichiosis (4)
Sxs, labs, blood smear w/ morulae (don’t hang your hat on it), PCR (takes weeks)
Treating ehrlichiosis
Tx w/ doxycycline immediately. Do not wait for confirmed diagnosis. Rapid response aids in diagnosis. Hematologic problems improve after 2-5 days. Transaminases take 2-3 weeks to normalize.
