Human granulocytic anaplasmosis and Anaplasma phagocytophilum.
Human granulocytic anaplasmosis is a tickborne rickettsial infection of neutrophils caused by Anaplasma phagocytophilum. The human disease was first identified in 1990, although the pathogen was defined as a veterinary agent in 1932. Since 1990, US cases have markedly increased, and infections are now recognized in Europe. A high international seroprevalence suggests infection is widespread but unrecognized. The niche for A. phagocytophilum, the neutrophil, indicates that the pathogen has unique adaptations and pathogenetic mechanisms. Intensive study has demonstrated interactions with host-cell signal transduction and possibly eukaryotic transcription. This interaction leads to permutations of neutrophil function and could permit immunopathologic changes, severe disease, and opportunistic infections. More study is needed to define the immunology and pathogenetic mechanisms and to understand why severe disease develops in some persons and why some animals become long-term permissive reservoir hosts.
Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. sdumler@jhmi.edu
J Stephen
JS
Dumler
Kyoung-Seong
KS
Choi
Jose Carlos
JC
Garcia-Garcia
Nicole S
NS
Barat
Diana G
DG
Scorpio
Justin W
JW
Garyu
Dennis J
DJ
Grab
Johan S
JS
Bakken
D041081:Anaplasma phagocytophilum / Q000145:classification / Q000235:genetics / Q000472:pathogenicity*; D000818:Animals; D016873:Ehrlichiosis / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology*; D006801:Humans; D009504:Neutrophils / Q000276:immunology / Q000382:microbiology; D010802:Phylogeny