health

Caused by an organism once thought to infect only dogs, sheep, cattle,
goats, and horses, ehrlichiosis was first discovered in humans in 1953 when
researchers in Japan found that Sennetsu fever, an illness that resembles
mononucleosis, was caused by Ehrlichia sennetsu bacteria. Between the
1980s and early 2000s, scientists identified three additional strains of
Ehrlichia bacteria that cause forms of human ehrlichiosis in the United States:
E. chaffeensis, which causes human monocytic ehrlichiosis (HME); bacteria
similar or identical to E. phagocytophila or E. equi (known to cause ehrlichiosis
in animals), which cause human granulocytic ehrlichiosis (HGE),
which later was called anaplasmosis; and E. ewingii, which has only been
seen in a few patients in the midwestern United States and Tennessee.