Human granulocytic anaplasmosis
| Pathogen: Anaplasma phagocytophilum |
| Tick vectors: Ixodes scapularis, Ixodes pacificus |
| Geographic distribution: Northeast and upper Midwest, northern Pacific coast |
| Classic presentation: Fever, headache, myalgia, malaise, cough, opportunistic infections in severe cases, thrombocytopenia, leukopenia, lymphopenia, elevated aminotransferase levels; laboratory abnormalities may no longer be present after 1 week of symptoms |
| Diagnosis: Polymerase chain reaction assay available; 4-fold increase between acute and convalescent serology with a minimum peak titer ≥ 1:64; morulae in granulocytes on Giemsa- or Wright- stained peripheral smear; cell culture rarely used |
| Treatment: Doxycycline, typically for 10 days (range 7–14 days) |