- Anaplasma phagocytophilum
- Obligate intracellular Gram-negative
- Recognized in early 1990s in Wisconsin and Minnesota – acute febrile tick-borne illness similar to ehrlichiosis
- Replicate in host granulocytes (versus monocytes for Ehrlichiosis)
Posted 08/15/16 09:17:28 AM by Matthew Cummings
- Reservoir – small mammals (mice, rats)
- Transmitted by Ixodes tick sp. --> same vector sp. as Lyme, Babesiosis
- Cases occur year-round, peak in summer months
- Highest annual incidence in New England, Mid-Atlantic and Upper Midwest States
Posted 08/15/16 09:18:11 AM by Matthew Cummings
- Similar clinical presentation to ehrlichiosis, RMSF
- Acute febrile, flu-like illness (headache, myalgia, fatigue, cough, nausea/vomiting, abd pain, diarrhea)
- Labs -- important diagnostic clues:
- Rash less common than ehrlichiosis and RMSF
Posted 08/15/16 09:19:11 AM by Matthew Cummings
- Anaplasmosis diagnosis
- Whole-blood PCR --> Sensitivity 60-90% prior to antimicrobials
- Blood smear review for intra-cytoplasmic morulae (Wright, Giemsa stains) --> Sensitivity 25-75%, highest within 1 week of illness onset
- Anaplasmosis-specific IgM and IgG --> May take 4-6 weeks to develop serologic positivity
Posted 08/15/16 09:20:15 AM by Matthew Cummings
- Anaplasmosis treatment
- As a rule – treat empirically if clinical picture suspicious PRIOR to confirmatory testing
- Doxycycline drug of choice -- 100mg twice daily --> also covers Ehrlichia sp. and RMSF
- Often see RAPID clinical response in 24-48 hrs
- Duration: Usually 10d or at least 3d after last fever
- If persistent fever > 48 hrs s/p doxy – reconsider diagnosis, ?Babesia co-infection
Posted 08/15/16 09:34:40 AM by Matthew Cummings
For further reading...
Posted 08/15/16 09:38:54 AM by Matthew Cummings
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