Pigs are considered a “mixing vessel” that can produce new influenza strains through genetic reassortments, which threaten public health and cause economic losses worldwide. We performed surveillance of swine influenza virus (SIV) using 114,140 nasal swabs from 11,414 Korean farms from 2009 to 2022, and characterized their genetic evolution at each farm level. A total of 169 farms out of the 11,414 (1.48%) were SIV-positive. The positivity rate for the H1N2 subtype, which is most dominant in the pig population, was 37.87% (64/169). Through hemagglutinin (HA) gene analysis, 64 H1N2-positive farms were classified into Eurasian avian-like (46/64, 71.88%), triple-reassortant (14/64, 21.88%), pdm09 (3/64, 4.69%), and classical swine (1/64, 1.56%) groups. The estimated evolutionary rate of HA in H1N2 from 2009 to 2022 in Korea is 1.5309 × 10-3/site/year (95% HPD intervals from 1.0003 × 10-3 to 2.1735 × 10-3) with an estimated mean growth rate of 0.0114. Estimates of the relative genetic diversity of clades over time suggested that the HA of H1N2 exhibited an increase in population size. The results of this study showed that the Eurasian avian-like-HA of the H1N2 subtype was dominant in the pig population. The continued evolution of the HA of H1N2, which is critical for cell entry, might lead to genetic diversity and the loss of vaccine cross-protection. These results indicate that continus surveillance is imperative for monitoring the evolution of the swine influenza virus.

Canine parvovirus type-2 (CPV-2) is a major etiological agent causing gastrointestinal enteritis in domestic and wild carnivores. Since the emergence of CPV-2 in the late 1970s, subtypes CPV-2a, CPV-2b, and CPV-2c have spread worldwide. CPV-2 prevalence differed according to region and season. This study aims to investigate the prevalence of CPV-2 infection in Korea. Samples were collected from 536 dog feces in animal shelters and 225 necropsied intestinal tissues of dog carcasses submitted in the Animal and Plant Quarantine Agency (APQA) for diagnostic purposes from 2016 to 2020 in Korea. Among the 761 samples, 181 (23.8%) were positive for the following subtypes: CPV-2a (n=138), CPV-2c (n=16), CPV-2b (n=14), and CPV-2 (n=2). Feline parvovirus (n=2) and co-infection with CPV-2a and CPV-2c (n=1) were also detected. There was no significant difference in the regional distribution of CPV-2 in Korea, which is prevalent in winter. This result shows the prevalence of CPV-2 according to various environments in Korea and will be useful in establishing an effective prevention strategy against CPV-2 that reflects the situation in Korea with continuous monitoring.

Guillain-Barré syndrome (GBS) is the most common cause of acute flaccid paralysis and autoimmune polyradiculoneuropathy. Campylobacter jejuni is the most commonly identified infectious trigger for GBS. A sialic-acid containing lipopolysaccharide (LPS) of Campylobacter is thought to be involved in the triggering of GBS. The galE (UDPgalactoset- epimerase) gene of Campylobacter spp. is involved in the synthesis of LPS. In this study, we detected the galE gene in Campylobacter spp. responsible for triggering the onset of GBS. The PCR assay detected the presence of the gene in 14 of the 25 (56%) Campylobacter isolates from domestic chicken, 20 of the 28 (71.4%) Campylobacter isolates from imported chicken and 50 of the 51 (98%) Campylobacter isolates from human clinical samples. Also, the specific 497-bp region of galE sequence in Campylobacters responsible for triggering the onset of GBS was amplified from GBS patient. These results could provide evidence of the first GBS-related C. jejuni infection in Korea.

To determine the prevalence of Campylobacter jejuni and Campylobacter coli in meats, a total of 4,161 samples (1,953 domestic and 2,208 imported) were collected from 304 slaughterhouses nationwide and registered cold storages for imported meats in Korea during 2005～2009. The isolation rates of C. jejuni and C. coli in domestic beef, pork, chicken and duck meats were 0.1% (1/630), 0% (0/630), and 0.1% (1/644), 0% (0/644) and 20.5% (125/609), 10.2% (62/609) and 25.7% (18/70), 20.0% (14/70), respectively. In the case of imported meats, C. jejuni were isolated from 0.1% (1/943) and 15.2% (83/546) of pork and chicken meats, respectively, and C. coli were detected only from 4.8% (26/546) of chicken meats. Neither C. jejuni nor C. coli were detected from imported beef, and C. coli were also not detected from imported pork. In conclusion, chicken meats had much higher rate of contamination with Campylobacter compared to beef and pork. Therefore, HACCP system that is now mandatory for slaughterhouses should be actively practiced for safe and sanitary processing, handling, and marketing of chicken meats. In addition, all critical control points should be determined by processing procedures at processing plants as well as farms and slaughterhouses, and monitoring should be carried out at regular intervals.