However, it seems unlikely that marine mammals would have the opportunity to ingest such fish with any frequency.
Transmission to humans occurs when eggs of the tapeworm, excreted by the final hosts (usually foxes but also dogs, wolves and cats), are ingested accidentally.
During inoculation care was taken to ensure that all the metacercariae were ingested by the experimental animals.
After parasite eggs are accidentally ingested by grazing snails, they develop within the snail and multiply asexually into cercariae.
Humans become infected by ingesting embryonated eggs from soil or contaminated food.
However, it is widely held that when ingested with food the infectious dose may be reduced by at least 1000-fold.
In a second case, liquid gelatin was employed which was also ingested though less readily than the previous liquid.
To complete the life cycle metacercariae must be ingested by definitive hosts.
