Ehrlichia, Anaplasma, and Rickettsia

Rickettsia, Ehrlichia, and Anaplasma are infections primarily transmitted by ticks (but, in the case of certain Rickettsial species, are transmitted by other vectors as well), which can cause an abrupt, febrile, and flu-like illness often associated with headache, nausea, vomiting, abdominal pain, rash, elevated liver function tests, and thrombocytopenia. Disease can be severe, particularly when patients are infected with Rickettsia rickettsii (Rocky Mountain Spotted Fever); patients may develop central nervous system involvement, shock, and multiorgan failure. Diagnostic tests are imperfect, and prompt empiric treatment should be initiated if disease is suspected. Doxycycline is the treatment of choice, and coinfection with other vector-borne pathogens may need to be considered.