A physician administers leeches to a patient. Colour reproduction of a lithograph by F-S. Delpech after L. Boilly, 1827.

Why Did the Victorians Harbor Warm Feelings for Leeches?

Medical authorities wrote about leeches as if they sucked blood out of the goodness of their hearts.

Scientists Are Putting Mosquitoes on Human Diet Drugs

Humans and mosquitoes share a surprising amount of genes and have similar hunger controls.
medical leeches

Medical Leeches Are Back (Yes, You Read That Right)

Leeches are especially helpful when veins are damaged and unable to properly drain blood from extremities, for example, in recently reattached amputations.
See page for author [CC BY 4.0 (http://creativecommons.org/licenses/by/4.0)], via Wikimedia Commons

Blood transfusion - 17th century (?)
"Anthropographia" (?) showing blood transfusion between man and sheep; ascribed to J. G. Riva (fl 1618) author of 'De triplici infusionis sanguinis experimento'
Iconographic Collections

First Blood Transfusion: A History

The world’s first experiments with blood transfusion occurred in the mid-1660s in England. The procedure, carried out between dogs, was gruesome.
Paganini's Bloodletting Kit 
Courtesy of Schubertiade Music & Arts

The Vampire Virtuoso? Paganini’s Bloodletting Kit Is for Sale

Paganini's personal bloodletting kit contains three domed-shape glasses with brass twist spouts and a brass scarification (scraping) tool.