| Species
|
Size
|
Shape
|
Color
|
Stage of Development When Passed
|
Specific Features and Variations
|
| TREMATODES |
| Schistosoma mansoni |
140 mm × 66 mm. Range, 114-180 mm × 45-73 mm. |
Elongated with prominent lateral spine
near posterior end. Anterior end tapered and
slightly curved. |
Yellow or yellow brown. |
Embryonated. Contains mature miracidium. |
Lateral spine. Found in feces; in rare
cases, in urine also. Eggs are discharged at
irregular intervals and may not be found in every
stool specimen. Are rare in chronic stages of
infection. |
| Schistosoma japonicum |
90 mm × 70 mm. Range, 68-100 mm × 45-80 mm. |
Oval. Small lateral
spine is often seen or may appear as a small hook
or "knob" located in a depression in
the shell. |
Yellow or yellow brown. |
Embryonated. Contains mature miracidium. |
Found in feces. Often coated with debris
and may be overlooked. |
| Schistosoma haematobium |
143 mm × 60 mm. Range, 112-170 mm × 40-70 mm. |
Elongated with rounded anterior end and
terminal spine at posterior end. |
Yellow or yellow brown. |
Embryonated. Contains mature miracidium. |
Terminal spine. Found in urine,
occasionally in feces. Egg often covered with
debris. |
| Schistosoma intercalatum |
175 mm × 60 mm. Range, 140-240 mm × 50-85 mm. |
Elongated with tapered anterior end and
terminal spine. Sometimes
"spindle-shaped." |
Yellow or yellow brown. |
Embryonated. Contains mature miracidium. |
Terminal spine long, slender with bent
tip. Resembles S. haematobium egg except
it is longer, is thinner, and has a longer spine. Found in feces.
May have debris adhering to
shell. |
| Schistosoma mekongi |
69 mm × 56 mm* Range, 51-73 mm × 39-66 mm. |
Spherical. Small
lateral spine, not always visible or may appear
as a small "knob" in a depression in
the shell. |
Yellow or yellow brown. |
Embryonated. Contains mature miracidium. |
Found in feces. Closely resembles S.
japonicum egg except it is smaller. May be
coated with debris. |
| Clonorchis sinensis |
30 mm × l6 mm. Range, 27-35 mm × 11-20 mm. |
Small, ovoidal, or elongated with broad
rounded posterior end and a convex operculum
resting on "shoulders." A small
"knob" may be seen on the posterior
end. |
Yellow brown. |
Embryonated. Contains mature miracidium. |
Small size, operculum and
"knob" on posterior end. Shell often is
covered by adhering debris. |
| Opisthorchis felineus |
30 mm × 12 mm. Range, 26-30 mm × 11-15 mm. |
Elongated with operculum on anterior
end and pointed terminal "knob" on
posterior end. |
Yellow brown. |
Embryonated. Contains mature miracidium. |
Lacks prominent shoulders characteristic
of Clonorchis and has more tapered end. |
| Heterophyes heterophyes |
28 mm × 15 mm. Range, 28-30 mm × 15-17 mm. |
Small, elongated or slightly ovoidal. Operculum. Slight "knob" at posterior
end. |
Yellow brown. |
Embryonated. Contains mature miracidium. |
Resembles Clonorchis egg but with
less distinct shoulders. Operculum is broader
than in Clonorchis. |
| Metagonimus yokogawai |
28 mm × 17 mm. Range, 26-30 mm × 15-20 mm. |
Small, elongated or ovoidal. Operculum. No "shoulders" at anterior end.
Small
"knob" often seen on posterior end. |
Yellow or yellow brown. |
Embryonated. Contains mature miracidium. |
Resembles Clonorchis and Heterophyes eggs.
Shell is slightly thinner than
Heterophyes. Operculum is broader than Clonorchis. |
| Paragonimus westermani |
85 mm × 53 mm. Range, 68-118 mm × 39-67 mm. |
Ovoidal or elongate with thick shell. Operculum is slightly flattened and fits into
shoulder area of shell. Posterior end is
thickened. Egg often asymmetrical with one side
slightly flattened. |
Yellow brown to dark brown. |
Unembryonated. Filled with yolk material
in which a germinal cell is imbedded. Cells are
irregular in size. |
Found in sputum, occasionally in feces. Resembles egg of D. latum but is larger,
slightly asymmetrical and the operculum is
smaller and flatter. The widest part of the Paragonimus
egg is usually anterior to the center; in a D. latum, the widest area is around the center. |
| Fasciola hepatica |
145 mm × 80 mm. Range, 120-150 mm × 63-90 mm. |
Ellipsoidal, thin shell. Small,
indistinct operculum. |
Yellow to light brown. |
Unembryonated. Filled with yolk cells in
which an indistinct germinal cell is imbedded. |
Large size. Broadly oval eggs. |
| Fasciolopsis buski |
140 mm × 80 mm. Range, 130-159 mm × 78-98 mm. |
Ellipsoidal, thin shell. Small,
indistinct operculum. |
Yellow brown. |
Unembryonated. Filled with yolk cells in
which an indistinct germinal cell is imbedded. |
Large size. Resembles F. hepatica egg and cannot be easily distinguished from Fasciola. |
