Schistosoma

Schistosoma Species

The schistosomes are also known as "blood-flukes"
There are several important species producing serious human and animal disease in the tropics
The pathology is mostly associated with the passage of eggs through the liver, urinary bladder or intestinal wall (depending on the predilection site of the fluke)
As their common name suggests, the adults live in blood vessels
Unusually for a trematode, the sexes are separate
The smaller female lies enveloped by the male
The eggs of most species have spikes to assist their passage through host tissue to get into faeces or urine (depending on predilection site)
The intermediate hosts are water snails
On release, the cercariae swim in water and actively seek their final host, which they enter by skin penetration
- There is therefore no metacercaria stage