[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 7 Miscellaneous Protozoa
161
FOCUSING IN
The remaining protozoa of human clinical significance
are described in this chapter. This group
of organisms is similar in that each of its members
is unicellular. However, the specific morphologic
forms, methods of laboratory diagnosis, life cycle
notes, epidemiology, clinical symptoms treatment
protocols, and prevention and control measures
vary among the organisms in this group.
Because of these variations, the specific information
associated with each of the protozoa is
described on an individual basis. In addition to
the laboratory diagnosis information in this
chapter, representative diagnostic methodologies
are discussed in Chapter 2.
In addition to a concise yet comprehensive
discussion of the well-known miscellaneous protozoa,
two relatively new genera, Cyclospora
and Microsporidia, are briefly mentioned in this
chapter. These organisms are known to produce
human intestinal disease. Because of their relatively
recent discovery and the fact that much
is still to be learned about these genera of
protozoan organisms, their exact classification
has not been well described.
MISCELLANEOUS PROTOZOA
CLASSIFICATION
The remaining members of the protozoa are classified
in four groups. The first group, the ciliates,
parasites that move by means of hairlike cytoplasmic
extensions called cilia, contains one
human pathogen known as Balantidium coli
(Fig. 7-1). The second group consists of select
sporozoa (Fig. 7-2), excluding Plasmodium and
Babesis spp., which are discussed in Chapter 6.
These parasites, which are intestinal and tissuedwelling
in nature, belong to the subclass Coccidia,
a group of protozoal parasites in which
asexual replication occurs outside a human host
and sexual replication occurs inside a human
host, and are often referred to as coccidian protozoans.
Blastocystis hominis (Fig. 7-3), initially
considered as a yeast, makes up the third group
and is now classified as a Protozoa. This organism
is the sole member of the class Blastocystea.
Phylum
Ciliophora
Class
Kinetofragminophorea
Intestinal Species
Balantidium coli
FIGURE 7-1 Parasite Classification: The Cilliates.
Phylum
Apicomplexa
Class
Sporozoa
Intestinal Species
Isospora belli
Sarcocystis species
Cryptosporidium parvum
Tissue Species
Toxoplasma gondii
FIGURE 7-2 Parasite Classification: The Sporozoa.