Faced with battlefield wounds on an unprecedented scale in the trenches of France during World War I, Johns Hopkins University physician William Baer began seeing injuries that had become infested with maggots. His first instinct was to clean out the larvae but then, like other doctors before him, he noticed something strange: the wounds with maggots didn't become infected, they healed faster, and the soldiers were much less likely to die of their injuries.
After the war, Baer returned to Johns Hopkins and brought his insights into maggot therapy with him. In particular, he wanted to try it on chronic bone infections known as osteomyelitis. He bred and raised Lucilia sericata maggots on the windowsill of his Baltimore laboratory, and used the larvae on 21 patients for whom all previous treatments had failed. Two months later, Baer noted, all of their wounds had healed. However, he discovered that several of the wounds had become infected with tetanus and gangrene. He realized that he needed to sterilize the larvae before using them on patients. After several years of experiments, he finally found that a solution of mercuric chloride, alcohol and hydrochloric acid did the trick without killing the eggs.
Throughout the 1930s and 40s, the popularity of maggot therapy blossomed -- at least, until the discovery of penicillin. Within a few decades, maggot therapy was relegated to a "historical backwater, of interest more for its bizarre nature than its effect on the course of medical science," said the microbiologist Milton Wainwright. It was "a therapy the demise of which no one is likely to mourn."