Shibasaburo Decodes the Plague

On this day in 1894, Japanese physician and bacteriologist Kitasato Shibasaburo discovered the infectious agent of the bubonic plague and published his findings in the journal The Lancet. However, French bacteriologist Alexandre Yersin also independently discovered the bacterium responsible for the Third Pandemic at the same time as Shibasaburo, and he is eventually recognised as the primary discoverer of the organism.

Born in Kumamoto, Japan, Shibasaburo pursued medicine at the University of Tokyo. Shortly after he completed his degree, he traveled to Berlin to work under Dr. Heinrich Robert Koch. There, Shibasaburo discovered how to grow a pure culture of tetanus bacillus. The following year, he and German microbiologist Emil von Behring developed a serum therapy for tetanus using this pure culture. Shibasaburo also made advances in understanding antitoxins, specifically for diphtheria and anthrax. He and von Behring found that animals injected with microbes that cause tetanus or diphtheria produce substances in their blood that neutralize the toxins produced by the microbes. What’s more, these antitoxins could be injected into healthy animals to provide them immunity to the microbes. This was considered a major advance in understanding the workings of the immune system and in developing vaccines for diseases.

But Shibasaburo’s greatest discovery came during a public health nightmare. The year 1894 in Hong Kong saw an outbreak of the bubonic plague, an episode that had begun in China decades earlier and would eventually spread to all inhabited continents. Shibasaburo was asked by the Japanese government to travel to Hong Kong to research the disease. In so doing, Shibasaburo made a breakthrough when he was able to isolate the bacterium that was causing the disease. But another bacteriologist—Alexandre Yersin of France—independently reached the same conclusion as Shibasaburo several days later. Unfortunately, Shibasaburo’s initial reports were vague and somewhat contradictory, so sole credit for the discovery was given to Yersin, who named the bacteria Pasteurella pestis in honour of the Pasteur Institute for whom he worked. In 1967, the organism was moved to a new genus and renamed Yersinia pestis in honor of Yersin.

As for Shibasaburo, he continued his distinguished work, discovering along with a student Shiga Kiyoshi the organism that caused dysentery and founding and heading Kitasato University. Shibasaburo was named the first president of the Japanese Medical Association in 1923 and was made a baron by the Emperor in 1924. He died on 13 June 1931, at the age of 78.