In a straw hut in a plague city, he found the germ behind the Black Death in about a week — then went back to a Vietnamese fishing village, and stayed.
When Alexandre Yersin landed in Hong Kong on 15 June 1894, more than 300 people were already dead. The same epidemic had just killed over 60,000 people in Canton in a matter of weeks, and the hospitals were losing about 95 of every 100 patients. He was 30, a doctor sent alone by the French colonial ministry. A Japanese team under Shibasaburō Kitasato, a celebrated pupil of Robert Koch, had arrived three days earlier, and the British medical authorities had reserved the hospital's bodies for it.
So Yersin had a straw hut built on the hospital grounds and, by the usual telling, paid the English sailors who carried away the dead. He opened a swollen bubo and found what he later described as "a veritable purée" of short, stocky bacilli with rounded ends. It was the answer to a question Europe had been asking since the 1340s. He could have gone home famous. He went back to Annam instead.
A life in six dates
The lifeline
1863
Born 22 September in Vaud, Switzerland; his father had died shortly before
1888
With Émile Roux in Pasteur's circle, shows that diphtheria kills by a toxin
1890
Quits the Institut Pasteur to be a ship's doctor on the Saigon–Manila line
1894
Hong Kong: isolates the plague bacillus in his straw hut, by Pasteur's dating on 20 June
1895
Founds the laboratory at Nha Trang that becomes a Pasteur Institute
1943
Dies at home in Nha Trang, aged 79, and is buried nearby at Suối Dầu, as he asked
By the numbers
The measure of the plague, and of him
about 7
Days from landing in Hong Kong to isolating the bacillus (sources run from 5 to 8)
95%
Death rate he recorded in the Hong Kong hospitals, often within 48 hours
60,000+
Dead in Canton within weeks that spring, by his count. Pasteur's history says 100,000
76
Years until the germ took his name: found in 1894, Yersinia pestis only from 1970
What he found, founded and planted
The work
1888
The diphtheria toxin. With Roux, he showed that a filtered, germ-free culture could still do the bacterium's harm. It opened the road to antitoxin treatment.
1890–94
Three expeditions across the Annam hinterland. In 1893 he reached the Lang Biang plateau, the site where Da Lat would rise.
1894
The plague bacillus. Six pages in the Annales de l'Institut Pasteur described the germ, found it in dead rats, and called rats its probable main vehicle. He also ground up a dead fly and killed a guinea pig with it. The flea was shown later, by Paul-Louis Simond in 1898.
1896
The first serum treatment. In Canton he treated and cured the first plague patient ever given antiserum. Trials at Amoy followed; at Bombay in 1897 the results disappointed.
1897–99
Rubber. He planted Indochina's first Hevea trees, 200 to begin with, at Suối Dầu. Sources date it to 1897 or 1899. The first crop went to Michelin in 1904.
1902
The Hanoi medical school, founded at the governor-general's request, with Yersin as its first head.
1915
Quinine. He opened a station on Hòn Bà and went on to acclimatize the cinchona tree, which let Indochina meet its quinine needs in the Second World War.
Late credit, from the people he lived among
Recognition
For decades
Kitasato was credited with the discovery for some years, on an earlier announcement
The germ was called Bacillus pestis, and from 1923 Pasteurella pestis, after his institute's founder
He lived half a world from Paris, on a farm on the Annam coast
He refused patients' fees, calling medicine "a calling, like priesthood"
Today
The organism has been Yersinia pestis since 1970
Vietnam made him an honorary citizen in 2014, and streets there still bear his name
His tomb has a small temple kept in flowers and incense, a rare honour for a foreigner
His house is the Yersin Museum, and a university in Da Lat is named for him
The place he chose
Nha Trang
He first came to this stretch of the Annam coast in 1891, when it was a scatter of fishing villages, and it was home for the rest of his life. He began the serum work with a house of temporary materials and a herd of horses. The villagers called him Ông Năm, "Mr. Five." He asked to be buried at Suối Dầu, on his own farm land, and thousands came to the funeral.
about 50
Years Nha Trang was home, from 1891 to 1943
about 20
Horses in the first serum stables, with one veterinarian
1,500 m
Height of Hòn Bà, his mountain station for cinchona
"I could never ask a patient to pay me for treatment."
— Alexandre Yersin, as quoted by the Institut Pasteur
