Field Guide to Venomous and Medically Important Invertebrates ...

leeches occur in a broad variety of standing freshwater habitats throughout the world. Other
species are marine while others occur in moist temperate and tropical terrestrial environments.
Although some leeches attach to vertebrate hosts to take a blood meal, most species are free-
living scavengers or predators and pose no threat to people. Representative blood-sucking
aquatic leaches occur in temperate and tropical aquatic habitats worldwide. Some common
blood-feeding leeches include the European medicinal leech (Hirudo medicinalis), Asian
medicinal leech (Hirudinaria manillensis) and the Amazon leech (Haementeria ghilianii). Also
of particular interest in Southeast Asia area are the land leeches (Haemadipsa spp.) all of which
are blood feeders. Blood-sucking terrestrial and aquatic leeches occur throughout East and
Southeast Asia and in some areas constitute a real annoyance for military personnel forced to
wade or crawl through swamps or travel in leech infested jungle. In Asia, leeches have been
reported from the sinuses of people who swam in infested water, and, in such circumstances, the
offending leech may have to be surgically extracted.
Figure 256. Amazon leech (Haementeria ghilianii). Photo: Mark Siddall.
Figure 257. Land leech (Haemadipsa sp.). Photo: Stanley Bender.
When a person enters leech-infested habitats, the leeches quickly swim towards the source of
water disturbance. Upon reaching the host, a leech will immediately adhere with one of the
suckers, then begin "exploring" in "measuring- worm" style over the skin surface. This may
continue for 20 or 30 seconds or the leech may release its grip and swim around to another site
and repeat the exploring action until a suitable attachment point has been selected. At this time
the shin of the host is quickly perforated with the three cutting plates with minute teeth which are
protruded into the cavity of the anterior sucker. As soon as the skin is perforated, suction begins