Besides maggots, leeches are another type of primeval worms that have been used medicinally since the early times. Neither slugs, reptiles, insects, or bugs, these invertebrates belong to a separate zoological category occupied by bristle worms. With suckers on both tips of their bodies and teeth that cut neatly into skin, leeches make perfect therapy for conditions like venous congestion, in which blood accumulates in a certain area of the body when the veins are unable to pump blood back to the heart.
In 2004, the FDA approved the use of leeches for medical purposes, particularly following surgeries such as limb reattachment and breast reconstruction. True to their reputation, these organisms are impeccable suckers, able to extract a substantial amount of blood in just 45 minutes. Aside from resolving blood pools, leeches also increase oxygenation around the affected area as they draw blood to it, as well as prevent blood clots through their blood-thinning saliva. Anemia is a major risk to maggot therapy, but this is usually handled easily in any well-managed medical environment.