Hospitals usually buy their supplies of maggots and leeches from special "farms" where they are grown under sterile conditions.
They raise them on farms
farms that raise cattle
To grow food and raise livestock and all that livestock.
you will find duck farms were they raise ducks on farms that is were you will find duck farms
they are farms that raise pitbulls and give them to a good home
Some people think that leeches are not good and it stinks...
Monoculture farms.
dead guys
Leeches are known as parasites but they can be useful in medicine. After surgery, some doctors use leeches to prevent dangerous swelling near a wound. Also, leeches make a useful chemical that people can use.
No. Such farms are becoming few and far between, and are more often small hobby farms rather than large "commercial" farms.
It would be very unusual for leeches to kill people, however, they do suck blood, and a person can die from blood loss. In order to lose that much blood, a person would have to be unconscious will leeches are feasting at will.