What are the prevention and control methods for swine epidemic encephalitis B

Swine epidemic encephalitis B is a zoonotic infectious disease caused by the Japanese encephalitis B virus. Mosquitoes are the long-term host and main transmitter of the virus, so the disease has an obvious seasonal pattern, occurring more frequently in summer and autumn when mosquitoes are active.

The disease can infect pigs of different ages, sexes and breeds, at around 6 months after birth. It generally occurs sporadically, with many inapparent infections, but regardless of whether symptoms are present, infected pigs are contagious in the early stage of infection. After infection, pigs mostly develop sudden onset of disease, with body temperature reaching around 41 degC, listlessness and reduced appetite. In pregnant sows it mainly causes abortion, stillbirth or premature birth, occurring more often in first-parity sows and less often after the second parity. The fetuses are mostly stillborn or mummified, or the piglets develop convulsions and die within a few days after birth. After abortion, the clinical symptoms of the sow quickly diminish, and body temperature and appetite return to normal, generally without affecting mating for the next parity. Boars often develop swelling of the testicles, mostly unilateral, with local heat and pain; after a few days it begins to subside, and most cases shrink and harden, with loss of mating ability. In other cases, only a few show neurological symptoms.

There is no good drug treatment for this disease. Antibiotics or sulfonamides can be used to prevent complications, while strengthening nursing care can promote recovery and reduce deaths.

For replacement gilts, inject the attenuated or inactivated encephalitis B vaccine at 5 to 6 months of age, repeat the injection once at an interval of 2 weeks in the first year, and then immunize 2 times each year thereafter. At the same time, strengthen mosquito control, which can effectively prevent abortion in sows.