Feral pigs are a growing problem in the United States and also on the southern prairies in Canada. As of 2013, the estimated population was 6million. A conservative estimate indicates that feral pigs cause about 1.5billion dollars in property and agricultural damage every year in the United States both in wild and agricultural lands. However, the actual cost is likely considerably higher. As of 2018 an estimate from the University of Georgia indicated it was closer to between 2billion and 2.5billion. Their ecological damage may be equally problematic with 26% lower vertebrate species richness in forest fragments they have invaded. Because pigs forage by rooting for their food under the ground with their snouts and tusks, a group of feral pigs can damage acres of planted fields in just a few nights. Because of the feral pig's omnivorous nature, it is a danger to both plants and animals endemic to the area it is invading. Game animals such as deer and turkeys, and more specifically, flora such as the "Opuntia" plant, have been especially affected by the feral hog's aggressive competition for resources. Feral pigs have been determined to be potential hosts for at least 34 pathogens that can be transmitted to livestock, wildlife, and humans. For commercial pig farmers, great concern exists that some of the hogs could be a vector for swine fever to return to the US, which has been extinct in America since 1978. Feral pigs could also present an immediate threat to "nonbiosecure" domestic pig facilities because of their likeliness to harbor and spread pathogens, particularly the protozoan "Sarcocystis".