Board Review: Bugs and Drugs
21-year-old-man who presents to the emergency department with a rash and a fever of 101.2. Patient noted a macular rash on his ankles and wrists and now has spread to the chest and back and appears petechial. Patient admits to hiking recently in North Carolina. Patient is found to have hyponatremia to 122, platelets are found to be low at 50K, and mildly elevated LFTs. Which of the following is the most likely diagnosis?
A. Babesiosis
B. Ehrlichiosis
C. Lyme Disease
D. Rocky Moutain Spotted Fever
Answer D: RMSF is a tick borne illness caused by Rickettsia rickettsi and most commonly occurs in the southeastern United States. Classic symptoms are fever, headache, myalgias, nausea, and vomiting. The rash is small red macules that begins on the ankles and feet and then spreads to palms and sole and thereafter centrally. In later stages, rash can become petechial.
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Regional Tick Borne Illness |
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Disease |
Geographic location |
Clinical Presentation |
Lab Abnormalities |
Diagnosis |
Treatment |
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Ehrlichiosis |
SE and south central US |
fever, HA, malaise, n/v/d, arthralgias. Severe: encephalitis, renal failure, respiratory distress |
pancytopenia, elevated AST, hyponatremia |
DNA PCR testing: Peripheral Smear->morulae in monocyte |
Doxycycline 100 mg 10 days: or 3-5 days after defervescence (whichever is longer) |
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Human Granulocytic Anaplasmosis |
NE and North Central and eastern US |
1-2 wks later w/ F, HA, myalgia: Rash is RARE |
transaminitis, leukopenia, thrombocytopenia |
PCR, serology; Peripheral smear->morulae in granulocyte |
Doxy 100 bid 10-14days |
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Babesiosis |
NE and North Central US |
Malaise, fatigue, anorexia, shaking chills, fever, headache, nausea, vomiting, myalgias, arthralgias, dark urine, SOB |
Hemolytic anemia, thrombocytopenia, transaminitis, Increased BUN and Cr |
PCR, blood smear (maltese cross in RBC) |
Mild to moderate: Atovaquone + azithro or clindamycin + quinine. Severe IV clinda + quinine +/- exchange transfusion |
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Lyme Disease |
Atlantic Central and North Central US |
1st stage: Erythema migrans w/ nonspecifc sx 2nd stage: fever, neuropathies (CN VII palsy), heart block, asymmetric arthritis. Late: chronic arthritis, myocarditis, encephalopathy, polyneuropathy |
non-specific |
ELISA or IFA (indirect Immunofluorescence) |
PPX: Doxy 200 mg PO X 1 w/in 72 hrs of bite Doxycycline, amoxicillin, or cefuroxime for 14-21 days |
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RMSF (rocky moutain spotted fever) |
Continental US, mostly south central and SE |
fever, headache, rash (macules later becoming petechial) begins at ankles and wrists and spreads centrally |
hyponatremia, thrombocytopenia, transaminitis |
IFA (indirect Immunofluorescence) |
Doxycycline 100 mg bid for 5-7 days or for at least 3 days after fever subsides |
Wilson, K et al. “ Whats Eating You? Ixodes Tick and Related Diseases: Part 2: Diagnosis and treatment of Regional Tick – borne Diseases.” Cutis. 2018 April ; 101(4):266-268; 305 <https://www.mdedge.com/dermatology/article/162955/infectious-diseases/whats-eating-you-ixodes-tick-and-related-diseases>
Bellis, J et al. “Tick-Borne Illness: Identification and Management in the Emergency Department.” <https://www.ebmedicine.net/topics/infectious-disease/pediatric-tick-born.... Sept 2, 2018.
Hu, L et al. “ Clinical Manifestations of Lymes Diseae.” May 2 2018. <www.uptodate.com> 9/26/19.
Hu, L et al. “ Treatment of Lyme Disease.” Sept 27, 2018. <www.uptodate.com>. 9/26/19.
Sexton, D et al. “ Clinical Manifestation and Diagnosis of Rocky Mountain spotted fever.” May 29 2018. <www.uptodate.com> .9/26/19.