Molecular Epidemiology of Viral Conjunctivitis in the Southern Region of South Korea, 2012–2016

Epidemic keratoconjunctivitis (EKC) and acute hemorrhagic conjunctivitis (AHC) are common diseases caused by human adenoviruses (HAdV) and enteroviruses, respectively, in South Korea. However, there are limited studies on the molecular epidemiology of viral conjunctivitis in South Korea. The main objective of this study was to characterize the genotypes of adenoviruses and enteroviruses causing viral conjunctivitis in the southwest region of South Korea. We collected conjunctival swabs from 492 patients with suspected cases of viral conjunctivitis from 6 ophthalmic hospitals in Gwangju Metropolitan City, in South Korea, between 2012 and 2016. Of the 492 samples tested, HAdVs and enteroviruses were detected in 249 samples (50.6%) and 19 samples (3.9%), respectively. The genotype analysis detected HAdV-8 in 183 samples (73.5%), HAdV-37 in 14 samples (5.6%), and HAdV-3, and HAdV-4 in 9 samples (3.6%) each. We detected coxsackievirus A24 (CVA24) and coxsackievirus B1 (CVB1) in 8 samples (42.0%) and 4 samples (21.0%), respectively. We also reported for the first time HAdV-56-infected cases of EKC in South Korea. Furthermore, we found three cases of coinfection with HAdV and enterovirus genotypes in our samples. HAdV-8 and CVA24, the main causes of EKC and AHC, respectively, worldwide, were also found to be the predominant genotypes in our study.

Seroepidemiological Survey of Zoonotic Diseases in Small Mammals with PCR Detection of Orientia tsutsugamushi in Chiggers, Gwangju, Korea

Serosurveillance for zoonotic diseases in small mammals and detection of chiggers, the vector of Orientia tsutsugamushi, were conducted from September 2014 to August 2015 in Gwangju Metropolitan Area. Apodemus agrarius was the most commonly collected small mammals (158; 91.8%), followed by Myodes regulus (8; 4.6%), and Crocidura lasiura (6; 3.5%). The highest seroprevalence of small mammals for O. tsutsugamushi (41; 26.3%) was followed by hantaviruses (24; 15.4%), Rickettsia spp. (22; 14.1%), and Leptospira (2; 1.3%). A total of 3,194 chiggers were collected from small mammals, and 1,236 of 3,194 chiggers were identified with 7 species of 3 genera: Leptotrombidium scutellare was the most commonly collected species (585; 47.3%), followed by L. orientale (422; 34.1%), Euchoengastia koreaensis (99; 8.0%), L. palpale (58; 4.7%), L. pallidum (36; 2.9%), Neotrombicula gardellai (28; 2.3%), and L. zetum (8; 0.6%). L. scutellare was the predominant species. Three of 1,236 chigger mites were positive for O. tsutsugamushi by PCR. As a result of phylogenetic analysis, the O. tsutsugamushi strain of chigger mites had sequence homology of 90.1-98.2% with Boryong. This study provides baseline data on the distribution of zoonotic diseases and potential vectors for the development of prevention strategies of vector borne diseases in Gwangju metropolitan area.

Molecular Epidemiology of Mumps Virus Circulated in Gwangju

The recent mumps epidemic in South Korea has generated a large amount of public concern. This study has attempted to analyze molecular epidemiological changes of mumps virus circulating in Gwangju metropolitan area, South Korea. 953 throat swab samples were collected from patients with parotitis from May 2013 to July 2014. The majority (71.5%) of these cases have occurred in middle or high school students aged from 15 to 19 years. All samples were tested using a reverse transcription polymerase chain reaction (RT-PCR) that targets the short hydrophobic (SH) gene of the virus. Mumps virus SH gene was detected in 39.2% (374/953) of samples. And 82 RT-PCR products were randomly selected for nucleotide sequencing analysis. All of these sequences were determined as genotype I by phylogenetic analysis and showed the highest nucleic acid similarity (99%) with Dg1062/Korea/98 (GenBank accession no. AY309060). These results suggested that appearance of new genotype or genetic variation at the nucleotide level could be ruled out to evaluate main cause of recent mumps outbreak in Gwangju metropolitan area.