About Ehrlichiosis

Human Ehrlichiosis is an emerging tick-borne infection that became reportable to the CDC, USA, in 1999.

The term Ehrlichiosis is a general designation encapsulating several tick-borne etiologic agents based on their similar clinical presentations. These obligate intracellular bacteria are both epidemiologically and etiologically distinct from one another. Recognized since 1935, Ehrlichia species were primarily viewed as veterinarial pathogens infecting sheep, goats, horses, cattle, and dogs. In 1953, Neorickettsia sennetsu was isolated in Japan from the first human infection, however, identification of the next human strain did not occur until 1986. At present, five strains capable of infecting humans have been identified and three (Anaplasma phagocytophilum, Ehrlichia chaffeensis and Ehrlichia ewingii) have been clinically characterized. Neither Ehrlichia canis nor Nerorickettsia sennetsu, the remaining human strains, have been sufficiently investigated.

Available Tests for Ehrlichiosis


Ehrlichia/Anaplasma EliSpot
(CPDA tube)


Ehrlichia-IgM and Ehrlichia-IgG-antibodies
(Serum tube)


Ehrlichia/Anaplasma-DNA-PCR in blood
(2 x EDTA tube)


Ehrlichia chaffeensis (Human Monocytic Ehrlichiosis = HME),
Anaplasma phagocytophilum (Human Granulocytic Ehrlichiosis = HGE)(gram-negative, obligatory intracellular in granulocytes)

Vector / Transmission:

Ixodes ricinus, Ixodes scapularis (deer tick)


game (e.g. deer), domestic animals, humans

Symptoms (incubation time: days up to four weeks):

rapid onset of beginning illness with fever, chills, headache and prostration, headaches are “sharp, knife-like and often located behind the eyes”, muscle pain, not joint pain, neurological symptoms, confusion, rarely diffuse vasculitic rash, including palms and soles (<10%), thromboctopenia, leukopenia, elevated liver enzymes

Risk factors:

tick-bites, older people, severe basic illness, immune suppression (children)