In 1910, Evans became one of the first women scientists to hold a permanent position at the U.S. Department of Agriculture Bureau of Animal Husbandry. She worked for the dairy division, researching the bacteriology of milk and cheese. From her studies, she identified a bacterial infection carried by cows that could cause undulating fevers in humans and published her findings in 1918. Researchers, veterinarians, and physicians were skeptical of her claim because they did not think that a woman, particularly one without a doctorate degree, could have made such an important discovery. Dairy workers laughed at her warning that raw milk should be pasteurized to prevent people from developing disease. However, other scientists came to the same conclusion in the late 1920s and by the 1930s, the government enacted milk pasteurization laws. Evans’ discovery prevented countless people from suffering from fevers and even death.