Schistosoma mansoni eggs are large (114 to 180 Ám long by 45-70 Ám 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: Eggs of S. mansoni in unstained wet mounts. Images courtesy of the Wisconsin State Laboratory of Hygiene.
C, D: Eggs of S. mansoni in unstained wet mounts. Images courtesy of the Missouri State Public Health Laboratory.
E, F: Eggs of S. mansoni in unstained wet mounts.
The eggs of Schistosoma japonicum are large and more rounded than other species, measuring 70-100 Ám long by 55-64 Ám wide. The spine on S. japonicum eggs is smaller and less conspicuous than other species. Eggs are shed in stool.
G, H: Eggs of S. japonicum in unstained wet mounts.
The eggs of Schistosoma haematobium are large (110-170 Ám long by 40-70 Ám wide) and bear a conspicuous terminal spine. Eggs contain a mature miracidium when shed in urine.
I, J: Eggs of S. haematobium in wet mounts of urine concentrates, showing the characteristic terminal spine.
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 Ám by 40-65 Ám). They also contain a small, inconspicuous spine and are shed in stool.
K: Egg of S. mekongi. Note the inconspicuous spine (red arrow).
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 Ám), often have an equatorial (central) bulge and are shed in stool, not urine.
L: Egg of S. intercalatum in a wet mount.