Movement
Leeches move using their longitudinal and circular muscles in a modification of the locomotion by peristalsis, self-propulsion by alternately contracting and lengthening parts of the body, seen in other annelids such as earthworms. They use their posterior and anterior suckers (one on each end of the body) to enable them to progress by looping or inching along, in the manner of geometer moth caterpillars. The posterior end is attached to the substrate, and the anterior end is projected forward peristaltically by the circular muscles until it touches down, as far as it can reach, and the anterior end is attached. Then the posterior end is released, pulled forward by the longitudinal muscles, and reattached; then the anterior end is released, and the cycle repeats. Leeches explore their environment with head movements and body waving. The Hirudinidae and Erpobdellidae can swim rapidly with up-and-down or sideways undulations of the body; the Glossiphoniidae in contrast are poor swimmers and curl up and fall to the sediment below when disturbed. Interactions with humans
Bites
Leech bites are generally alarming rather than dangerous, though a small percentage of people have severe allergic or anaphylactic reactions and require urgent medical care. Symptoms of these reactions include red blotches or an itchy rash over the body, swelling around the lips or eyes, a feeling of faintness or dizziness, and difficulty in breathing.
Botryomycosis; is a rare chronic granulomatous bacterial infection that affects the skin, and sometimes the viscera. : 255 Botryomycosis has been known to affect humans, horses, cattle, swine, dogs and cats. Presentation
Associated conditions
There are only a handful of documented cases of botryomycosis in humans, and its pathogenesis is not completely understood. However, it is usually described in individuals with impaired immunity, or with an underlying disease such as diabetes mellitus, cystic fibrosis or HIV infection. Causes
Staphylococcus aureus is usually the organism that causes the infection, however it can also be caused by Pseudomonas aeruginosa, Pneumocystis carinii, Proteus spp. and Actinobacillus lignieresii or other species of bacteria. The anatomic structure of its lesion is similar to that of actinomycosis and eumycetoma, and its granules resemble the sulfur granules of actinomycosis. Diagnosis
History
The disease was originally discovered by Otto Bollinger (1843–1909) in 1870, and its name was coined by Sebastiano Rivolta (1832–1893) in 1884. The name refers to its grape-like granules (Gr. botryo = grapes) and the mistakenly implied  fungal etiology (Gr. mykes = fungus). In 1919 the bacterial origin of the infection was discovered. Notes
Concise Review of Veterinary Microbiology - Quinn and Markey 2003

External links
Essay on Pulmonary Botryomycosis