Not long after the present pandemic of plague reached the shores of America in 1900, where it was recognized in the Chinese colony of San Francisco, it was found to be present among the ground squirrels in Contra Costa County. At that time the close association of rodent and human plague was not so clear as it is at present. In 1900, when my plague experience began, the work of the English and the German plague commissions in India was only fairly begun and the idea of flea transmission was new and not generally known.
In the early days of any revolutionary discovery there is a period when those who accept it have their thinking partially clouded by the holdover of ideas from the past, and we who took part in the early history of plague in America1 were in that transitional stage. We knew that the rat was
KELLOGG WH. RODENT PLAGUE IN CALIFORNIA. JAMA. 1935;105(11):856-859. doi:10.1001/jama.1935.02760370012005