Maggots were not used to treat diseases, but they were used to heal wounds during World War I.
Some doctors caring for the injured during the war noticed that certain patients’ wounds healed more quickly and were more resistant to infection than others’.
At closer look, they realized those patients had flies landing on their open sores.
“Fly-blown” wounds seemed to contain some healing and antibiotic properties that medical professionals couldn’t ignore, especially during war.
To make the conditions a bit more safe, doctors took flies and sterilized their maggots before placing them on open sores.
Thankfully, scientists discovered the healing substances, allantoin and urea, and extracted them, bypassing the menacing go-between, the fly.
Despite their war effort, flies are still known carriers of typhoid, cholera, salmonella, dysentery, leprosy, tuberculosis, and many other life-threatening diseases.