Jean Danysz (1860–1928) was a Polish pathologist with a considerable career in France, having spent much of his adult life at the Pasteur Institute in Paris.
[1] He was contacted in 1905 regarding Australia's rabbit plagues[5] and responding to the New South Wales government's offer of £25,000 for a novel solution to the country's rabbit pest problem, he arrived in Australia the following year to advise on biological control measures.
[6] He brought a strain of Pasteurella bacteria which he had developed to selectively kill feral rabbits and conducted a series of trials on Broughton Island, New South Wales coast with his team.
His organism was eventually proved to be identical to one already known to science, and although it was not found to be injurious to other animals, it was ineffective as a control.
[7] The Danysz phenomenon, where a toxin added to antitoxin in an equal amount at once is non-toxic but when added at intervals in a fraction results in a generally toxic mixture, was named for him.