Wild hogs are known to cause external damage to land, property and wildlife, but the internal diseases they carry are equally dangerous.
More than 40 known diseases are traced to wild hogs, but the two most common in Mississippi are pseudorabies and swine brucellosis. Each can be deadly to livestock and domestic animals. The best way to prevent these infections is to trap and kill hogs rather than simply building fences to keep them out.
“Fencing wild hogs out of a home place or pasture is certainly possible, but costly to maintain,” said Bronson Strickland, a wildlife biologist and management specialist with the Mississippi State University Extension Service. “Wild hogs are good at rooting under fences, so eliminating them is the best option.”
Also known as Aujesky’s disease, pseudorabies is a widespread viral disease in wild hog populations transmitted through sexual or nose-to-nose contact. It can also be spread through ingestion of infected tissues. Pseudorabies infections almost always kill livestock and pets.
Anthony Ballard, nuisance wildlife biologist with the Mississippi Department of Wildlife, Fisheries and Parks, said infections can cause “mad itch” — which includes self-mutilation and incessant scratching — in many species.
“In hogs, clinical signs vary with age and previous exposure to this disease within the population,” Ballard said. “Neonatal and young piglets experience a high level of mortality due to encephalitis. Subadult and adult hogs can experience a variety of symptoms, including high fever, loss of coordination, anorexia, tremors, vomiting, diarrhea and reproductive failures or complications. Other populations of hogs may even remain asymptomatic and simply serve as a reservoir for this disease.”
Unlike pseudorabies, swine brucellosis can be transmitted to humans as well as livestock and pets. In swine, transmission of this bacterial disease can occur through mucosal membranes, damaged skin, sexual contact and ingestion of infected tissues.
Strickland said humans become infected with brucellosis when blood, fluids or tissue from a wild hog come in contact with eyes, nose, mouth and cuts in the skin. Another common exposure route is eating undercooked wild hog. Meat must be cooked well done, or 160 degrees in the center.
“Symptoms of brucellosis in humans are similar to the flu: fever, excessive sweating, headaches, fatigue and joint and muscle pain,” he said. “In domestic swine, infection can cause lesions, abscesses, paralysis and inflamed reproductive organs.”
Mark Crenshaw, Extension professor in the MSU Department of Animal and Dairy Science, said cattle can also contract brucellosis, but infections are rare.
“When infection does occur, the characteristic infection is mastitis, with brucellosis organisms excreted in the milk,” Crenshaw said. “This presents a public health risk.”
Wild hogs are also indirectly involved in common foodborne illnesses, including E. coli, salmonella and trichinosis. Humans can contract each of these diseases through undercooked or contaminated food. Swine and livestock contract E. coli and salmonellosis by ingesting fecal-contaminated material or salmonella bacteria, and infection usually causes fever and diarrhea.
A parasitic disease, trichinosis is caused by roundworms found in wild hogs and transmitted to animals through the ingestion of tissues. Swine are at a higher risk than other animals of becoming infected. Symptoms in humans are vomiting, fever and abdominal pain.
Leptospirosis is another bacterial disease that can affect humans and other mammals. This pathogen remains viable in soil or water for long periods of time, and it infects hogs, rats, foxes, coyotes, raccoons and livestock.
“Wild hogs spread leptospirosis by urinating in streams, creeks and ponds,” Ballard said. “Humans can contract it through cuts and abrasions or through mucosal membranes. Symptoms of leptospirosis in humans include flu-like symptoms, fever, vomiting, abdominal pain, muscle aches, jaundice and in severe cases, kidney damage. Leptospirosis targets the urinary system, particularly the kidneys.”
In areas where wild hogs are commonly seen, knowing the symptoms of infection in livestock and pets and getting help is key to their survival.
“For livestock diseases, contact your veterinarian and also consider contacting the Mississippi Board of Animal Health,” Strickland said. “For pets, a veterinarian would be a good source of knowledge regarding what steps to take next.”