Classification: ICD-9 083.8; ICD-10 A77.4
Syndromes and synonyms: Human monocytic ehrlichioses (HME), human granulocytic anaplasmosis (HGA), Sennetsu fever.
Agent: Obligate intracellular, pleomorphic bacteria of the family Anaplasmataceae, which invade host leukocytes. Ehrlichia chaffeensis infects mononuclear phagocytes; E. ewingii and Anaplasma phagocytophilum infects neutrophils. E. canis may cause human disease in Venezuela. In 2009 an E. muris-like organism was discovered in USA. Neorickettsia sennetsu causes Sennetsu fever.
Reservoir: Deer and dogs (E. chaffeensis, E. ewingii). The white-tailed deer is a complete host for maintaining the transmission cycle of E. chaffeensis. Deer, ruminants, and field rodents (A. phagocytophilum); unknown for N. sennetsu; other members of the genus parasitize the trematode worms of aquatic vertebrates and invertebrates.
Vector: Ticks of the genera Amblyomma and Ixodes.
Transmission: By tick bites, except for N. sennetsu, which is probably transmitted through ingestion of uncooked, parasitized aquatic hosts. No person-to-person spread except by blood transfusion.
Cycle: Tick to mammalian host to tick for Ehrlichia and Anaplasma; trematode to aquatic host to trematode for Neorickettsia
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
