He started to serve in 1883 in the Naval Medical Corps in Hong Kong, where he worked with Dr Patrick Manson, who studied the mosquito transmission of the parasitic worm, filaria, the cause of elephantiasis.

[3] There, he dedicated himself to the nascent field of toxicology, which had important connections to immunology, and he studied snake and bee venom, plant poisons and curare.

Work in this field was later taken up by Brazilian physician Vital Brazil, in São Paulo at the Instituto Butantan, who developed several other antivenoms against snakes, scorpions and spiders.

[4] Calmette's main scientific work – which was to bring him worldwide fame and permanently attach his name to the history of medicine – was the development of a vaccine against tuberculosis, which, at the time, was a major cause of death.

The German microbiologist Robert Koch had discovered, in 1882, that its pathogenic agent was the tubercle bacillus, Mycobacterium tuberculosis, and Louis Pasteur became interested in it too.

In 1906, a veterinarian and immunologist working at the Institut Pasteur de Lille, Camille Guérin, established that immunity against tuberculosis was associated with the living tubercle bacilli in the blood.

[6] He was the brother of Gaston Calmette (1858–1914), the editor of Le Figaro who was shot and killed in 1914 by Henriette Caillaux after running a long press campaign against her husband.