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Intestinal Trematodes 193

Paragonimus westermani infections are most Treatment and Prevention
frequently diagnosed by the presence of eggs in the
sputum. Larvae may develop into adults in the bronchio- Praziquantel is available for treatment of the condi-
lar area and may be seen there. tion, as for many other trematodal infections. Cultural
changes in attitude and practice and the undertaking
of lifestyle changes to aid in the prevention of infection
is the best method of control for P. westermani. These
MICROSCOPIC DIAGNOSTIC changes would include avoidance of poorly or under-
FEATURE cooked crabs and crayfish, as well as personal hygiene
and sanitary practices in disposing of human wastes and
living conditions.
General Classification—Flukes of
the Lungs
SCHISTOSOMES AND
Organism Paragonimus
westermani SCHISTOSOMIASIS
Specimen Required Sputum specimens
most commonly, Schistosomiasis is a disease caused by the blood fluke,
less often in stool a significant nematode, and is a condition that has been
specimens recognized for hundreds if not thousands of years.
Stage Adults are reddish- Schistosomiasis is also known as bilharzia, particularly
brown and live in in Egypt and nearby regions, an endemic region for the
capsules of the disease today, is caused by trematode worms belong-
bronchioles ing to the genus Schistosoma. Three species of Schisto-
Size Adults are 10 3 8 mm soma are important: S. haematobium, S. mansoni, and
(roughly 1 cm) S. japonicum. In 1910 Marc Armand Ruffer apparently
Shape Adults of found S. haematobium eggs in two Egyptian mummies
Paragonimus spp. dating from at least 1000 BC. This finding that is widely
are large, robust, accepted as the beginning of the subdiscipline of parasi-
ovoid flukes. They tology is called palaeoparasitology.
are hermaphroditic,
with a lobed ovary This disease, called schistosomiasis, is no doubt an
located anterior to ancient malady and is found in ancient written records
two branching testes. and archaeological evidence exists that attests to this
Like all members of fact. Early medical practitioners documented the passage
the Trematoda, they of bloody urine, a condition that is called hematuria and
possess oral and that today is associated with S. haematobium infections.
ventral suckers.
The genus Schistosoma, when broken down, literally
Motility Motility in fresh water refers to a splitting of the body (schisto- refers to split, or
Other Features Shell of egg is thin cleft, and soma- means body). There was nothing excep-
but thickens toward tional in early medical records regarding the symptoms
the flattened opercu- of schistosomiasis that might have attracted the attention
lum (lid)
of early victims. No recent evidence has emerged to lead
Must be to the belief that schistosomiasis is not an antique disease
differentiated from
Diphyllobothrium that has continued in importance epidemiologically for
latum at least several thousand years. Thus, there is direct evi-
dence that schistosomes were present in ancient Egypt
Wet mount from
sputum may reveal where they are still prevalent and there have been numer-
eggs in some patients ous attempts to find descriptions of this condition in the
medical writings of that era.