Biomedical Engineering Reference
In-Depth Information
In some species (including Plasmodium ovale, Plasmodium vivax, but not in
Plasmodium malariae) a dormant variant of merozoite is produced that can
produce a malarial relapse after decades of remission [77].
The Genus Plasmodium has some very distinctive features, not the least
of which is its uniquely low G
C
ratio of about 20%, much lower than the ratios seen in the so-called low
G
C ratio. Plasmodium falciparum has a G
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C bacteria (Class Bacilli and Class Clostridia, Chapter 12), that hover
just under 50%.
Human babesiosis is uncommon, but this organism infects many mam-
mals other than humans, and is the second most common parasitic blood
disease of non-human mammals (after trypanosomal infections).
Two species infect humans: Babesia divergens, the most common cause
of babesiosis in Europe, and Babesia microti, the most common type of
babesiosis in North America [78]. The tick, Genus Ixodidae, serves an
almost identical role for Genus Babesia as the Anopheles mosquito serves
for Genus Plasmodium: sporozoites develop in the salivary gland of the tick
and are introduced into the human host, via a bite. In babesiosis, unlike
malaria, infection occurs exclusively in red cells and is not found in liver
cells. Aside from humans, animal reservoirs of Babesia microti and Babesia
divergens include mice and deer. Like malaria, babesiosis can be transmitted
via transfusions with contaminated blood products (see Glossary item, Blood
contamination).
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Apicomplexa
Conoidasida
Coccidia
Eucoccidiorida
Eimeriorina
Cryptosporidiidae
*Cryptosporidium
Eimeriidae
*Cyclospora
*Isospora (same as Cystoisospora)
Sarcocystidae
*Sarcocystis
*Toxoplasma
Six species of Class Coccidia produce disease in humans: Cryptosporidium
parvum, Cyclospora cayetanensis, Cystoisospora belli (Isospora belli),
Sarcocystis suihominis, Sarcocystis bovihominis, and Toxoplasma gondii.
As a subclass of Class Apicomplexa, the members of Class Coccidia are
obligate intracellular parasites. Nonetheless, Class Coccidia confers two fea-
tures that make it possible for coccidan species to survive outside the host,
for a period of time. First, there is the durable coccidian oocyst. Most cocci-
dians attach to enterocytes (particularly, the epithelial cells that line the small
