Ehrlichia under our noses and no one notices.

1: Arch Virol Suppl. 2005;(19):147-56. Related Articles, Links

Ehrlichia under our noses and no one notices.

Walker DH.

Department of Pathology, Center for Biodefense and Emerging
Infectious Diseases, University of Texas Medical Branch, Galveston, TX
77555-0609, USA. dwalker@xxxxxxxx

Ehrlichia chaffeensis, an obligately intracellular bacterium,
resides within a cytoplasmic vacuole in macrophages, establishes
persistent infection in natural hosts such as white-tailed deer and
canids, and is transmitted transstadially and during feeding by ticks,
particularly Amblyomma americanum. Ehrlichial cell walls contain
glycoproteins and a family of divergent 28 kDa proteins, but no
peptidoglycan or lipopolysaccharide. The dense-cored ultrastructural
form preferentially expresses certain glycoproteins, including a
multiple repeat unit-containing adhesin. Ehrlichiae attach to
L-selectin and E-selectin, inhibit phagolysosomal fusion, apoptosis,
and JAK/STAT activation, and downregulate IL-12, IL-15, IL-18, TLR2 and
3, and CD14. Mouse models implicate overproduction of TNF-alpha by
antigen-specific CD8 T lymphocytes in pathogenesis and strong type 1
CD4 and CD8 T lymphocyte responses, synergistic activities of IFN-gamma
and TNF-alpha, and IgG2a antibodies in immunity. Human monocytotropic
ehrlichiosis (HME) manifests as a flu-like illness that progresses in
severity to resemble toxic shock-like syndrome, with
meningoencephalitis or adult respiratory distress syndrome in some
patients, and requires hospitalization in half. In immunocompromised
patients, HME acts as an overwhelming opportunistic infection. In one
family physician's practice, active surveillance for three years
revealed an incidence of 1000 cases per million population. Diagnosis
employs serology or polymerase chain reaction, which are not utilized
sufficiently to establish the true impact of this emerging virus-like
illness.

Publication Types:

* Review


PMID: 16358425 [PubMed - indexed for MEDLINE]

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