Midwest and Eastern US
Can co-infect w/organisms causing Lyme and babesiosis
Walking in an endemic area wearing shorts, t-shirts and not using tick repellent (e.g. DEET containing products)
More severe if immunocompromised by meds, disease (eg. HIV), or s/p splenectomy

Often leukopenia, thrombocytopenia, and elevated transaminases
Organism sometimes visible on smear; can also detect by PCR and antibody testing

Anaplasmosis