Japanese encephalitis in pigs is an infectious disease caused by Japanese encephalitis virus, which is mainly spread by blood-sucking insects such as mosquitoes. Pregnant sows have stillbirth, boars have orchitis, fattening pigs have persistent high fever, and piglets have encephalitis symptoms. Porcine Japanese encephalitis virus is the same virus as human and horse Japanese encephalitis virus. The virus exists in brain, cerebrospinal fluid, brain tissue of stillbirth, spleen and swollen testis. The virus has weak resistance to the outside world, it can be inactivated at 56℃ for 30 minutes, and its activity can be rapidly reduced below pH7.0, and it can be stored for a long time at low temperature. 1% Lysol can inactivate the virus in 5 minutes, and common disinfectants have good disinfection effect.

Susceptibility to this disease is the highest among young pigs. Sick pigs and latent infected pigs are the main sources of infection. The disease is often spread by the bite of poisonous mosquitoes.

The occurrence of this disease has obvious seasonality, and it is generally prevalent from July to September, mostly sporadic or endemic. Pigs can be infected regardless of breed and sex. The sick pig will not recur after recovery, and the boar will have orchitis. The first sow has abortion, stillbirth, mummy and so on. Viremia occurred in pigs 3 ~ 7 days after infection with the disease. At this time, insects suck blood, carry viruses, bite people and pigs, and spread. The virus enters a new organism, circulates through the blood to various organs, and then reproduces in the central nervous system. In most cases, the virus only stays in the internal organs, does not cause nervous system symptoms, and is asymptomatic infection. Mosquitoes with viruses are contagious all their lives, can survive the winter, and can also become the storage host of viruses through egg transmission.