The number of wild boars is rapidly increasing in Japan due to a decline in the population in forest areas while climate change now allows the animals to thrive in the north; lower numbers of licensed hunters have also allowed the population to increase. Wild boars carry and spread many zoonotic diseases. These diseases may be food-borne, vector-borne (by mosquitos or ticks, for example), or transmitted by the fecal-oral route. An outbreak of Japanese encephalitis, which originates in wild boars, occurred in Karachi, a pig-free area in 1979. In Toyama Prefecture, wild boars have shown high-titer antibodies, implicating the boars as a reservoir of Japanese encephalitis. Additionally, severe fever with thrombocytopenia syndrome (SFTS) circulates between ticks and wild boars, and that virus is transmitted to humans by tick bites. Rabies is transmitted to wild boars through bites from infected foxes and hounds, and infected and violent wild boars sometime transmit the virus to humans. Ascariasis has decreased in Japan, however, the recent interest in organic fertilizer may lead to an increase in cases. Undercooked wild boar meats are also believed to transmit many zoonotic parasites (trichinosis, onchocerciasis, gnathostomiasis, paragonimiasis and cryptosporidiosis.), viruses (hepatitis E, swine influenza and Nipah virus) and bacteria (Rickettsia japonica).
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