The Leeches came

According to MSN Encarta the term Leech isthe common name for carnivorous or bloodsucking worm once widely used by physicians and barbers for bloodletting and still used for this purpose in some regions of the world.

Leeches continue to be used to relieve blood congestion in certain delicate operations, where such use is less likely to cause infection than other techniques.

Leeches are widespread in marine waters and are found [expoiting] in fresh water and on land in temperate and tropical regions.

Leeches like vampires are suckers if you can get the message!