Peering through his microscope in 1910, Franco-Canadian microbiologist Félix d'Hérelle noticed some "clear spots" in his bacterial cultures, an anomaly that turned out to be viruses preying on the bacteria. Years later, d'Hérelle would come to use these viruses, which he called bacteriophages, to treat patients plagued with dysentery after World War I.
In the decades that followed, d'Hérelle and others used this phage therapy to treat bubonic plague and other bacterial infections until the technique fell into disuse after the widespread adoption of antibiotics in the 1940s.
