Japanese Encephalitis in pig populations of Cachar district of Southern Assam: Emphasizing the need for enhanced surveillance.

Background objectives: Japanese Encephalitis (JE) is a re-emerging vector-borne zoonotic disease with a significant public health impact in India. JE is endemic in several Indian states, including Assam, which consistently reports the high burden of human JE cases in the country. Pigs, as amplifier hosts for the JE virus plays a critical role in JE transmission cycle and serves as suitable sentinels for predicting human JE outbreaks. Although several studies have assessed the JE prevalence in pigs across different districts of Assam, there is no prior report of occurrence of JE in pigs from Southern region of Assam. The present study was undertaken to determine the occurrence of JEV infection in pigs from Cachar, a Southern district of Assam through serological and molecular testing.

Methods: A total of 100 pig serum samples collected from backyard farms across eight villages in the Cachar district were screened using indirect ELISA(s) to detect JEV-specific IgM and IgG antibodies. Samples were further subjected to nested RT-PCR for viral RNA detection followed by phylogenetic analysis to identify the circulating JEV genotype in the region.

Results: Of the 100 pig serum samples tested, 59% were positive for JEV specific IgM antibodies whereas 53% samples were positive for IgG antibodies. The overall seropositivity of JEV among pigs from Cachar district was 66%. JEV RNA was detected in 12 samples and phylogenetic analysis confirmed the presence of genotype III of JEV circulating among pigs from Cachar district of Assam.

Interpretation conclusion: This is the first study to report the presence of JEV infection in pigs from the Cachar district of Assam, underscoring the need to initiate JEV surveillance in the pig population of the region.