Microscopy

Schistosoma mansoni

Schistosoma mansoni eggs are large (114 to 180 µm long by 45-70 µm wide) and have a characteristic shape, with a prominent lateral spine near the posterior end.  The anterior end is tapered and slightly curved.  When the eggs are excreted in stool, they contain a mature miracidium.

A	B

A, B: Eggs of S. mansoni in unstained wet mounts.  Images courtesy of the Wisconsin State Laboratory of Hygiene.

C	D

C, D: Eggs of S. mansoni in unstained wet mounts.  Images courtesy of the Missouri State Public Health Laboratory.

E	F

E, F: Eggs of S. mansoni in unstained wet mounts.

Schistosoma japonicum

The eggs of Schistosoma japonicum are large and more rounded than other species, measuring 70-100 µm long by 55-64 µm wide.  The spine on S. japonicum eggs is smaller and less conspicuous than other species.  Eggs are shed in stool.

G	H

G, H: Eggs of S. japonicum in unstained wet mounts.

Schistosoma haematobium

The eggs of Schistosoma haematobium are large (110-170 µm long by 40-70 µm wide) and bear a conspicuous terminal spine.  Eggs contain a mature miracidium when shed in urine.

I	J

I, J: Eggs of S. haematobium in wet mounts of urine concentrates, showing the characteristic terminal spine.

Schistosoma mekongi

Schistosoma mekongi is a species similar to S. japonicum that is restricted to the Mekong River area of southeast Asia.  The eggs are similar to S. japonicum, but are generally smaller (50-80 µm by 40-65 µm).  They also contain a small, inconspicuous spine and are shed in stool.

K

K: Egg of S. mekongi.  Note the inconspicuous spine (red arrow).

Schistosoma intercalatum

Schistosoma intercalatum is related to S. haematobium, but restricted to east-central Africa.  The eggs are similar to S. haematobium in general shape and in possessing a terminal spine, but are usually longer (140-240 µm), often have an equatorial (central) bulge and are shed in stool, not urine.

L

L: Egg of S. intercalatum in a wet mount.