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Intestinal Trematodes 195

TABLE 8-2 Characteristics of Schistosoma spp. Ova

SCHISTOSOMA SCHISTOSOMA SCHISTOSOMA
MANSONI HEMATOBIUM JAPONICUM
Size 115–180 3 40–80 μm 110–170 3 40–70 μm 50–80 3 40–60 μm
Appearance Spine located laterally Spine located terminally *Spine small and lateral

*Frequently not recognizable

MICROSCOPIC DIAGNOSTIC FEATURE

General Classification—Blood Flukes

Organism Schistosoma sp.
Specimen Required Adult blood flukes are worms that parasitize chiefly the mesenteric
blood vessels
Stage May be found in blood vessels, although the diagnostic stages
involve chiefly the finding of ova for differentiation of species
Size Adult schistosomes range from 7–20 mm for males and 7–26 mm
for females
Shape Varies by species
Motility Cercariae swim in water where hatched and penetrate skin
Other Features Adults live in blood vessels of viscera of mammals; eggs enter
bladder or intestine and are evacuated into water where the
eggs hatch into miracidia that enter snails. Sporocysts develop
from these miracidia and evolve into cercariae that are capable
of penetrating the skin of a suitable host, where they develop
into adults.

Schistoma sp. ova
S. mansoni S. japonicum S. hematobium

Delmar/Cengage Learning