Last Updated on October 31, 2023

The US swine industry, including the Swine Health Information Center (SHIC), continues to prepare for the possible incursion of Japanese encephalitis virus (JEV) in pigs. The threat of JEV has prompted the USDA APHIS Veterinary Services division to issue a statement regarding related testing and preparedness. The statement also addresses the diagnostic submission process and USDA plans for further preparedness activities.  

Diagnostic testing for any animals with clinical signs suggesting of Japanese encephalitis virus (JEV) is available at no cost to animal owners and producers at the National Veterinary Services Laboratories (NVSL) in Ames, Iowa. Veterinarians and producers must first notify their State or Federal Animal health officials if JEV is on a differential list, and these officials will assist in the submission and sampling as needed. NVSL uses both PCR and sequencing to identify and confirm the virus. While serology has proven useful in the surveillance and diagnosis of JEV in endemic countries, it is of limited use in JEV free countries and will not be offered as an on-demand diagnostic test at NVSL at this time. USDA scientists are actively collaborating with partners to develop and characterize additional diagnostics, and in the future USDA will expand their active JEV research program to the National Bio and Agro-Defense Facility, once the facility is fully operational, to better understand the pathogenesis, evolution and epidemiology of JEV. 

The US is considered a geographic region at risk for the introduction of Japanese encephalitis, a disease capable of affecting humans as well as pigs. JE is transmitted primarily by Culex mosquitoes infected with the virus. Environmental conditions similar to JEV endemic countries, as well as the availability of susceptible hosts and vectors, create concern for the US pork industry and public health officials. Clinical signs of JEV in the breeding herd includes reproductive failure, delayed farrowing, stillbirths, mummified fetuses, abortions, and weak or shaker piglets.

Additional information regarding animal JEV diagnostic testing is available from NVSL (515-337-7551;