Infection of Feral Phenotype Swine with Japanese Encephalitis Virus.

Background: Japanese encephalitis virus (JEV) is a mosquito-borne zoonotic flavivirus and the leading cause of pediatric encephalitis in the Asian Pacific region. The transmission cycle primarily involves Culex spp. mosquitoes and Ardeid birds, with domestic pigs (Sus scrofa domestica) being the source of infectious viruses for the spillover of JEV from the natural endemic transmission cycle into the human population. Although many studies have concluded that domestic pigs play an important role in the transmission cycle of JEV, and infection of humans, the role of feral pigs in the transmission of JEV remains unclear. Since domestic and feral pigs are the same species, and because feral pig populations in the United States are increasing and expanding geographically, the current study aimed to test the hypothesis that if JEV were introduced into the United States, feral pigs might play a role in the transmission cycle. Materials and Methods: Sinclair miniature pigs, that exhibit the feral phenotype, were intradermally inoculated with JEV genotype Ib. These pigs were derived from crossing miniature domestic pig with four strains of feral pigs and were used since obtaining feral swine was not possible. Results: The Sinclair miniature pigs became viremic and displayed pathological outcomes similar to those observed in domestic swine. Conclusion: Based on these findings, we conclude that in the event of JEV being introduced into the United States, feral pig populations could contribute to establishment and maintenance of a transmission cycle of JEV and could lead to the virus becoming endemic in the United States.

North American domestic pigs are susceptible to experimental infection with Japanese encephalitis virus.

Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus that is capable of causing encephalitic diseases in children. While humans can succumb to severe disease, the transmission cycle is maintained by viremic birds and pigs in endemic regions. Although JEV is regarded as a significant threat to the United States (U.S.), the susceptibility of domestic swine to JEV infection has not been evaluated. In this study, domestic pigs from North America were intravenously challenged with JEV to characterize the pathological outcomes. Systemic infection followed by the development of neutralizing antibodies were observed in all challenged animals. While most clinical signs were limited to nonspecific symptoms, virus dissemination and neuroinvasion was observed at the acute phase of infection. Detection of infectious viruses in nasal secretions suggest infected animals are likely to promote the vector-free transmission of JEV. Viral RNA present in tonsils at 28 days post infection demonstrates the likelihood of persistent infection. In summary, our findings indicate that domestic pigs can potentially become amplification hosts in the event of an introduction of JEV into the U.S. Vector-free transmission to immunologically naïve vertebrate hosts is also likely through nasal shedding of infectious viruses.

Evaluation of State Plans and the Livestock Emergency Response Plan (LERP).

The Livestock Emergency Response Plan (LERP) was published in 2014 as a toolkit to assist state agricultural emergency planners in writing or modifying state foreign animal disease/high-consequence disease (FAD/HCD) plans. This research serves as a follow-up to and expands on an initial survey conducted in 2011 by the Department of Homeland Security Office of Health Affairs, Food, Ag, and Veterinary Defense Branch. The purpose of this project is to describe the status of current state animal disease response plans in relation to how closely their content, order, and terminology relate to that described in the LERP template. The analysis was compared to the 2011 study to identify advances, trends, continued areas for increased alignment, and fulfillment of planning gaps in individual state plans. While vast improvements were made in the status of state animal disease response plans from 2011 to 2016, there is nonetheless significant room for enhancing consistency between and identifying gaps in FAD/HCD plans. As awareness of the LERP toolkit grows, the authors hope its use as a template by the states will expand accordingly, thereby increasing consistency between plans and more thoroughly addressing challenges in an FAD/HCD outbreak. The results of this study support the need for curriculum planning resources at the state level. Development of a training curriculum and planning workshops for state agriculture emergency planners will produce a consistent planning philosophy and skill set among state planners-another means of indirectly addressing current planning gaps in agricultural emergency response.