One of the most common diseases spread by feral swine is leptospirosis, Broom writes. It's a disease that U.S. Department of Agriculture data says 61 percent of wild hogs in Mississippi have been infected with at some point in their lives, according to Mississippi Department of Wildlife, Fisheries, and Parks biologist Anthony Ballard. (Year of first recorded occurrence of wild hogs: 2015 study by Conservation Science Partners, Colorado State University and USDA)
One problem is that "when the bacteria is shed, it lingers," living outside the host for weeks of months, Broom writes. "We see outbreaks of it during flooding events. Anything that drinks that water, including humans, has the ability to contract that disease. Wild hogs are such a reservoir for so many diseases. Hogs are hosts to about 30 types of bacterial and virulent diseases and 37 parasites. They can contract things and live with it that will kill other animals. They can carry on, do their thing and basically be unaffected," Ballard told Broom.