Anaplasma phagocytophilum: Difference between revisions
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Anaplasma phagocytophilum
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+ | ==Background== |
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* Causes '''human granulocytotropic anaplasmosis''' |
* Causes '''human granulocytotropic anaplasmosis''' |
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+ | ===Microbiology=== |
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− | === Microbiology === |
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+ | *Small, obligate intracellular Gram-negative bacterium |
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+ | *Related to ''[[Ehrlichia]]'' and ''[[Rickettsiae]]'' |
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+ | *Tropism for neutrophils |
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+ | ===Epidemiology=== |
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+ | *Rare case reports in Ontario |
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+ | *Transmission may take as little as 24 hours of tick attachment |
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− | == |
+ | ==Diagnosis== |
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− | == |
+ | ==Management== |
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+ | *[[Doxycycline]] 100 mg po bid until at least 72 days after defervescence |
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− | == Management == |
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+ | **Possibly 10 days if risk of concurrent [[Lyme disease]] |
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− | * Doxycycline 100 mg po bid |
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{{DISPLAYTITLE:''Anaplasma phagocytophilum''}} |
{{DISPLAYTITLE:''Anaplasma phagocytophilum''}} |
Latest revision as of 12:23, 8 July 2023
Background
- Causes human granulocytotropic anaplasmosis
Microbiology
- Small, obligate intracellular Gram-negative bacterium
- Related to Ehrlichia and Rickettsiae
- Tropism for neutrophils
Epidemiology
- Transmitted by Ixodes scapularis and Ixodes pacificus ticks
- Rare case reports in Ontario
- Transmission may take as little as 24 hours of tick attachment
Clinical Manifestations
- Incubation period of 1 to 2 weeks
- Usually an acute undifferentiated fever
- Can be mild or severe
- Fever, headache, malaise, and myalgias are common
- Can also cause nausea, vomiting, diarrhea, cough, arthralgias, nuchal rigidity, and confusion
- Less than 10% have rash, most of which is concurrent Lyme disease
- 36% of cases require hospitalization, and it is severe in 3 to 7%
- Severe complications include respiratory failure, septic shock, rhabdomyolysis, hemorrhage, and opportunistic infections
- Rare meningoencephalitis
- Higher case-fatality rate in Shandong Province in China, for no clear reason (16% versus 2.6%)
- Thrombocytopenia, leukopenia, and mild anemia are common
- Return to normal range within 14 days, but with persistent left shift
- Abnormal liver enzymes are common in the first 7 days
Diagnosis
- 20-80% of patients will have circulating neutrophils with detectable morulae on blood film (in neutrophils/granulocytes)
- Serology used to diagnose, by measuring IgG levels ≥1:64 or a fourfold rise
- IgM testing less sensitive and specific
- Culture not done routinely
- PCR possible
Management
- Doxycycline 100 mg po bid until at least 72 days after defervescence
- Possibly 10 days if risk of concurrent Lyme disease