The idea of things like fleas, ticks, bedbugs, mosquitoes, etc. sucking our blood is unpleasant at best. But sometimes a bloodsucker is exactly what is needed from a medical standpoint. After microsurgery on something like a finger, a bloodsucking leech can help improve blood flow and thereby speed healing:

Where do medical leeches come from? This video shows several different aspects of leech treatments in Russia, and shows how they raise them there:

Blood suckers in Russia

Maggots can also be used medicinally. They are able to find and eat dead tissue in a wound and leave the healthy tissue in place:

For more info on wound-healing see: How does a cut on your skin heal itself?

If you would like to buy leeches, you can find them at a place like this:

Buy Medical Leeches