Wild hogs in Mississippi are reservoirs of disease
Published 2:06 am Sunday, May 14, 2017
JACKSON — Most everyone who has encountered wild hogs knows the non-native species is a problem. Feral swine destroy crops, root up food plots and out-compete deer and other native wildlife species for food. But pigs present another danger — leptospirosis.
“Leptospirosis is a bacterial infection,” said William McKinley, Mississippi Department of Wildlife, Fisheries, and Parks wildlife biologist. “It’s common in the environment.
“Multiple animals can get it including deer and humans. Wild hogs are a reservoir for it, meaning they are walking around shedding it everywhere. It is primarily passed through urine.”
Not only are wild hogs shedding the disease, they seem to be doing a lot of it. MDWFP nuisance animal biologist Anthony Ballard said research done by the US Department of Agriculture indicates 61 percent of the wild hogs in Mississippi have been infected with the disease at some point in their lives.
And when the bacteria are shed, it lingers. According to the Centers for Disease Control and Prevention, leptospira can live outside a host for a matter of weeks or months, depending on conditions. If a water source is infected, it becomes more of a risk.
“We see outbreaks of it during flooding events,” Ballard said. “Anything that drinks that water, including humans, has the ability to contract that disease.
“It is definitely a concern. 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.”
In deer, particularly young and unborn deer, that’s not the case.
“It can cause abortions and kill young deer,” McKinley said. “Young deer are most likely to be killed by it.
“Older deer can carry it. The older deer may not show symptoms.”
Hogs are in every county in Mississippi now with more in some areas than others. In the southwestern part of the state, hunters cried loudly recently the deer herd is in decline. It’s also an area with a large population of wild pigs. So, with feral swine carrying the disease and hunters reporting fewer deer, could there be a correlation?
“The reports we are getting are reports of extremely high density in southwest Mississippi,” McKinley said. “I’ve had several people report killing a pig for every two to three acres. Some of these properties, 1,000-acre properties, report killing 300 to 500 a year.”
Another suspicious example is Sunflower Wildlife Management Area which also supports a significant population of wild pigs. In a 2016 interview, MDWFP biologist Jackie Fleeman said fawn recruitment is an issue and included disease as one of the possible contributing factors.
“There’s just not the deer out there that there should be,” Fleeman said. “The forest habitat is great.
“There is food out there for the deer. They should be fat and happy. We’ve done health checks and does are being bred. Between there and 1 year old, something’s happening. To me, the main problem is after they (fawns) are dropping, something is killing them.”
Although it’s possible that the levels of leptospirosis in Mississippi wild hogs could be negatively impacting deer density in some areas, there is no smoking gun. For now, it’s a suspicion and McKinley said he hopes to further investigate the significance of diseases being transmitted from wild hogs to deer.
“It is in the environment, but it was at very low rates,” McKinley said. “I can’t say it’s at higher rates. It is suspected it’s at higher rates because of the high rates in hogs.”