Biomedical Engineering Reference
In-Depth Information
members of Class Alpha Proteobacteria, and has been exploited, in the past,
to weaponize strains of Brucella.
Readers should be aware that brucellosis has been known by a great
number of different names, including undulant fever (from the undulating,
wave-like, progression of fevers), Malta fever, and Mediterranean fever.
Mediterranean fever, an arcane synonym for brucellosis, should not be con-
fused with familial Mediterranean fever (a gene disorder characterized by
fever and abdominal pain) or with Mediterranean anemia (a synonym for
thalassemia).
Alpha Proteobacteria
Rickettsiales
Anaplasmataceae
*Neorickettsia
*Ehrlichia
*Anaplasma
*Wolbachia
Rickettsiaceae
*Rickettsia
Class Anaplasmataceae includes four genera containing human pathogens:
Neorickettsia, Ehrlichia, Wolbachia, and Anaplasma. All the pathogenic spe-
cies are intracellular, are morphologically similar to one another, and produce
similar diseases.
The disease ehrlichiosis is actually a collection of different infections,
caused by organisms in Genus Ehrlichia, Genus Anaplasma, and Genus
Neorickettsia, and are vectored from animal reservoirs, by any of several
species of ticks (with one exception, Neorickettsia sennetsu, transmitted by
trematodes). After inoculation into humans, the organisms that cause ehrlich-
iosis invade and inhabit white blood cells, wherein they can be visualized by
microscopic examination. As you would expect from a disease of white cells,
the symptoms of ehrlichiosis are systemic, and include headache, fatigue,
and muscle aches.
The species producing ehrlichioses include: Ehrlichia ewingii (human
ewingii ehrlichiosis), Ehrlichia chaffeensis (human monocytic ehrlichiosis),
and Ehrlichia canis (Rickettsia-like infection), Neorickettsia sennetsu (sen-
netsu Ehrlichiosis), and Anaplasma phagocytophilum [25]. The last-listed
Ehrlichiosis pathogen, Anaplasma phagocytophilum, causes human granulo-
cytic anaplasmosis. Anaplasma phagocytophilum is the name given to one
organism formerly assigned, erroneously, to two different species: Ehrlichia
phagocytophilium and Ehrlichia equi [26]. Anaplasma phagocytophilium is
endemic to New England and to north-central and north-west United States.
Ehrlichia ewingii is primarily an infection of deer and dogs. It occurs in
humans most commonly in the south central and southeastern states.
Ehrlichia chaffeensis is most common in the south central and southeastern
