Tick Borne Diseases Flashcards
Lyme Disease: Important facts
- transmitted by tick bite
- TICK MUST BE ATTACHED FOR 36-48 hrs or more before B. Burgdorferi can be transmitted
- 30% of pt don’t recall tick bite (PAINLESS) but recall being outside
- Children and young adults mostly affected (camping, hiking)
Lyme Disease Stages
1. Localized infection (within a month): Erythema migrans (90% of patients) , (+/-) flu-like symptoms (fever, headache, myalgia)
- Disseminated infection (weeks):
Carditis (pericarditis, myocarditis, AV blocks) in <10% of untreated patients
Neurologic conditions (meningitis, encephalitis, radiculopathy, cranial nerve palsy) in 10% of untreated patients. - Disseminated infection (months-years):
Migratory arthralgia or arthritis (large joints) in 60% of untreated patients
Bell’s Palsy
most common neurologic manifestations of Lyme disease
Signs of Bell’s Palsy
- inability to wrinkle brow
- drooping eyelid, inability to close eye
- inability to puff cheeks; no muscle tone
- drooping mouth, inability to smile or pucker
Tests for Lyme Disease
- Cultures (blood, CSF, synovial): “Gold standard” but rarely positive
- IgM: IgM is detected within 6-8 weeks»_space; Negative IgM CAN NOT exclude early disease»_space; Early disease is diagnosed by clinical presentation (rash) and epidemiology (outdoor activity)
- IgG: IgG develop slowly and PERSIST FOR LIFE (but do not confer immunity and re-infection may reoccur)»_space; Negative IgG excludes late disease
Lyme Disease Tx
- Erythema migrans, Bell’s Palsy, Arthritis: Doxycycline or Amoxicillin x 14 days
- Carditis, CNS (meningitis, encephalitis): Ceftriaxone 2g/d IV x 14 days
Diagnosis of Lyme disease
- Erythema migrans + outdoor activity in Northeast/Midwest»_space; no tests»_space;proceed for therapy
- Arthritis, neurologic and cardiac symptoms suspicious for late Lyme disease»_space; IgG titers (positive ELISA should be confirmed by Western blot)
Asymptomatic tick bite
single dose of Doxycycline 200mg given only if:
- endemic region
- attached for > 36 hours
- Antibiotic should be given within 72 hours of tick removal
Patient education (Lyme Disease)
Wear long sleeved shirts, long pants (tuck shirts/ pants)
Wear light colors
A nightly “tick check”
Use insect repellent (containing DEET)
Rocky Mountain Spotted Fever
Rickettsia Rikettsii – gram negative bacteria. Organism enters the host via tick bite (dog tick, wood tick).
TICK BITE REMEMBERED
RMSF is most likely reported in the southeastern and south central US (“Appalachian fever”) during summer months
R. rickettsii spreads through blood stream > invades endothelial cells»_space; vasculitis (bleeding and microinfarcts) and vascular permeability (edema)
RMSF clinical manifestation
Acute onset of HIGH FEVER, SEVERE HEADACHE, (+/-) arthralgia. Patients often appear toxic.
RASH begins on the extremities and spreads to the trunk 5 DAYS AFTER SYMPTOMS BEGIN (spotted fever): macular that become petechial overtime
When to suspect RMSF
Fever, headache, and rash during SUMMER months + camping/hiking in endemic areas +/- tick bite
Meningeal Signs (RMSF)
Kernig Sign: bend KNEE elicits pain in lower back
Brudzinski: bend neck elicits hip and knee flexion
WBC in CSF analysis
- < 5 WBC- normal
- > 1,000 WBCs ( w/ 80% neutrophils)»_space;> bacterial meningitis
- <1000 WBCs ( w/ 50% lymphocytes)»_space;> viral, TB, Lyme, RMSF, fungal
Tests for RMSF
- CBC: Non-specific. Leukocytosis may be seen
- BMP: Non-specific. Hyponatremia may be seen in severe cases
- Blood cultures: R.Rikettsii cannot be cultured
- Serology: Negative serology cannot exclude the disease. IgM- appear 10 days after the onset of illness. It can confirm the dx retrospectively
- Immunologic testing of skin biopsy: Determine the presence of R.Rikettsii. Sensitive but not widely available.
- CSF analysis: Useful to r/o bacterial meningitis (WBC > 1,000s with predominance of neutrophils) but not to diagnose RMSF meningitis or encephalitis (a lot of other microorganisms may cause WBC is < 1,000 with predominance of lymphocytes)
