* 29.1.1881 Neath, Pennsylvania - † Arlington, Virginia 5.9.1975.

After completing high school, she taught for four years before enrolling in a two-year course for rural teachers at Cornell University in Ithaca, New York. There she became interested in science and completed a B.S. at Cornell and an M.S. at the University of Wisconsin, Madison, both in bacteriology. She was encouraged to continue for a doctorate but chose instead to work on the bacteriology of milk and cheese for the dairy division of the U.S. Department of Agriculture. Her work on the bacteria of milk led to her groundbreaking work on brucellosis, a bacterial infection (not yet known by that name), that she determined could cause both spontaneous abortions in animals and remittent fever in humans.

Evans published the results of her work in 1918, but researchers, veterinarians, and physicians were skeptical about her claim that the pathogens were zoonotic (i.e., caused symptoms in animals and in humans). The dairy profession also scoffed at her warning that raw milk should be pasteurized to safeguard human health. Two years later, a scientist at the University of California proposed a new genus, Brucella, to include both the bacteria pathogenic to humans and those pathogenic to cattle, while Evans continued her work on various species of the bacteria. In 1922 Evans herself became infected, and for more than two decades she suffered periodic bouts of brucellosis.

Thanks to the pioneering work of Evans, by the late 1920s brucellosis was understood not only as an occupational hazard for farmers but also as a threat to the food supply. Once the American dairy industry reluctantly accepted the need to pasteurize all milk, the incidence of brucellosis declined. In recognition of her achievement, in 1928 the Society of American Bacteriologists elected Evans as the organization's first woman president.

Evans retired in 1945, although she remained professionally active.