Biologist Jörg Graf researches bacteria in the bellies of bloodsuckers.

Many patients these days suffer from immune system deficiencies. Thus it is important for doctors to know which bacteria live in the blood of a leech before they decide whether to use leeches as medical treatment. It is also important to know which bacteria are in there which prevent infection. As with all living creatures, leeches are not sterile; and are the home of many bacteria. If a leech is squeezed as it is removed from the skin, it may regurgitate into the fresh wound. This can lead to infection. As leech therapy is used more and more, the need for studies of the bacteria in the bellies of the beasts is becoming more and more important.


Until recently it was assumed that leech stomach bacteria were all aerobic; however, new studies point to a richer array of bacterial dwellers. Jörg Graf, a German biologist and researcher at the University of Connecticut, has been studying leeches intensively for years. His team has succeeded in verifying and breeding another breed of bacteria. The new bacteria are anaerobic and propagate only in oxygen-free chambers.