Jama 1996;275:199 (HGE); Mmwr 1996;45:798 (HME); 1995;44:593; Ann IM 1994;120:730, 736

Cause:Ehrlichia sennetsuand chaffeensis(human monocytic ehrlichiosis) (HME) (Nejm 1996;334:209); and Anaplasma phagocytophilia, and ewingii(human granulocytic ehrlichiosis (HGE) (Nejm 1999;341:148, 195) anaplasmosis

Pathophys: Intracellular in polys, si and sx same in both types

Tick-borne (Ixodes scapularisand Amblyomma americanum), common in animals. Two types: HME in Southeast Asia (where causes a mononucleosis-like SENNETSU FEVER), now >300 cases in southern and central US from deer ticks, eg, Tennessee golf course epidemic (Nejm 1995;333:420); and HGE in midwestern and northeastern US (Ann IM 1996;125:904; 1995;123:277; Jama 1994;272:212)

Sx: ±10-d incubation period from tick bite. Acute self-limited febrile illness, headache, malaise, chills, nausea and vomiting

Si:Fever; occasionally cough; arthralgias; confusion; papular, rarely macular rash

Fatalities among the elderly age >60 yr

Pericarditis (Nejm 1996;334:213); perinatal transmission to newborn (Nejm 1998;339:375)

r/o RMSF and concomitant or distinct Lyme disease or babesiosis (Nejm 1997;336:15; Jama 1996;275:1657)

Lab:

Chem:LFTs elevated

Hem:CBC shows pancytopenia, esp thrombocytopenia, and diagnostic mulberry-like inclusions in polys (morulae) (80%) (see Nejm 1995;332:1417) in HGE, rarely seen in HME type

Serol:Diagnostic IFA acute (often neg) and convalescent titers

Rx:

Prevent w insect repellent and other antitick measures.

Doxycycline or other tetracycline; chloramphenicol