clothes. Nicolle managed to attract Hélène Sparrow to be Laboratory Chief in Tunis. She had worked with Rudolf Weigl who had developed a vaccine, and she was able to introduce this to Tunisia as the start of a public health programme to control the disease. Nevertheless, three other scientists also identified the bacterium responsible for the disease: Ricketts, Russell Morse Wilder (1885–1959), and Prowazek, who called it Rickettsia prowazekii. Chantemesse's typhoid vaccine During the summer of 1900, the extremely hot weather and scarcity of the water supply in Paris, usually ensured by the Ourcq channel and by the de la Dhuis aqueduct, forced the authorities to pump water directly from the Seine, which, despite filtering, led to a sudden and alarming outbreak of typhoid cases in Paris. The cause of the disease, a bacillus that was discovered almost twenty years before by the German bacteriologist Karl Joseph Eberth and that looks like a bodiless spider, was constantly present in this river and not even pouring extensive quantities of ozone and of lime permanganate into its water was enough to exterminate the bacteria. The difficulty in creating a vaccine is caused by the nature of the germ's endotoxins. Unlike diphtheria, which releases toxins via exocytotic secretion, typhoid pathogens encapsulate endotoxins that survive even after the death of the bacillus. After working in the rabies division of Rue Vaquelin and studying the microbe that causes dysentery, André Chantemesse collaborated with a younger bacteriologist, Georges-Fernand Widal. Together they were able to immunize guinea pigs by inoculating them with heat-treated dead bacteria, calling into question the notion that only weakened, not dead, bacteria can be used to immunize. They concluded that a series of three or four early injections of such heat-inactivated bacteria can effectively inoculate against the development of the disease, as the endotoxins alone are sufficient to trigger the production of antibodies. Fourneau and the Laboratory of Medicinal Chemistry Regarding curative medicine, it was in 1911 that it took off at the Institut Pasteur, when Ernest Fourneau created the Laboratory of Medicinal Chemistry, which he directed until 1944, and from which emerged numerous drugs, among which one can mention the first pentavalent arsenical treatment (Stovarsol), the first synthetic alpha-adrenoreceptor antagonist (Prosympal), the first antihistamine (Piperoxan), the first active drug on heart rate (Dacorene) or the first synthetic no-depolarising muscle relaxant (Flaxedil). The discovery of the therapeutic properties of sulfanilamide by Tréfouël, Nitti