Jae Keun Chung

Accuracy of Diagnostic Methods and Surveillance Sensitivity for Human Enterovirus, South Korea, 1999–2011

The epidemiology of enteroviral infection in South Korea during 1999–2011 chronicles nationwide outbreaks and changing detection and subtyping methods used over the 13-year period. Of 14,657 patients whose samples were tested, 4,762 (32.5%) samples were positive for human enterovirus (human EV); as diagnostic methods improved, the rate of positive results increased. A seasonal trend of outbreaks was documented. Genotypes enterovirus 71, echovirus 30, coxsackievirus B5, enterovirus 6, and coxsackievirus B2 were the most common genotypes identified. Accurate test results correlated clinical syndromes to enterovirus genotypes: aseptic meningitis to echovirus 30, enterovirus 6, and coxsackievirus B5; hand, foot and mouth disease to coxsackievirus A16; and hand, foot and mouth disease with neurologic complications to enterovirus 71. There are currently no treatments specific to human EV infections; surveillance of enterovirus infections such as this study provides may assist with evaluating the need to research and develop treatments for infections caused by virulent human EV genotypes.

Incidence and Characteristics of Scarlet Fever, South Korea, 2008–2015

The incidence rate for scarlet fever in South Korea is rising. During 2008–2015, we collected group A Streptococcus isolates and performed emm and exotoxin genotyping and disk-diffusion antimicrobial tests. Scarlet fever in South Korea was most closely associated with emm types emm4, emm28, emm1, and emm3. In 2015, tetracycline resistance started increasing.

Prevalence of human papillomavirus infection and genotype distribution among high-risk Korean women for prospecting the strategy of vaccine development

We investigated the prevalence of human papillomavirus (HPV) infection and the distribution of high-risk HPV genotypes among 2,308 high-risk Korean women to predict how much the current prophylactic HPV vaccines might affect the prevention of cervical cancer in Korea. HPV DNA was detected in 939 women (40.7%) but only one-third of women were positive for HPV-16 and/or HPV-18, the genotypes used for developing the HPV vaccines. Thus, the development of area-specific HPV vaccines based on dominant HPV genotypes in our country is needed for preventing HPV infection and the development of premalignant lesions in the cervix of Korean women.

Incidence of benign convulsions with mild gastroenteritis after introduction of rotavirus vaccine

BACKGROUND AND PURPOSE Rotavirus was the most common virus in benign convulsions with mild gastroenteritis (CwG), with an incidence of 40-50%. As rotavirus gastroenteritis has decreased since introduction of rotavirus vaccine, we investigated the incidence of CwG and rotavirus positivity after introduction of the vaccine. METHODS We retrospectively reviewed the medical records of 987 patients aged between 3months and 3years who were admitted to the Chonnam National University Hospital between March 2005 and February 2014 due to their first seizures and enrolled 102 patients with CwG. The incidences of CwG among seizure patients and stool rotavirus positivity in CwG patients were compared between two periods: period I (March 2005-February 2010) and period II (March 2010-February 2014). Other viruses in stools were also reviewed. RESULTS The incidence of CwG were 8.47% (45 among 531 patients) in period I and 12.50% (57 among 456 patients) in period II (P=0.018). Stool rotavirus was checked in 85.29% (87 patients): 82.22% (37 patients) in period I and 87.72% (50 patients) in period II (P=0.166). The positivity of rotavirus was 40.54% (15 patients) in period I and 16.00% (8 patients) in period II (P=0.01). In the patients without rotavirus gastroenteritis, 30 patients were test for other viruses. Norovirus was the most common (56.67%, 17 patients) and was more frequent in period II than I (71.43% versus 22.22%, P=0.018). CONCLUSION After introduction of rotavirus vaccine, rotavirus-associated CwG has decreased but the incidence of CwG has increased due to an increase of norovirus.

Diversity of Rotavirus Strain Circulated in Gwangju, Republic of Korea

Objectives The introduction of new rotavirus vaccines into the public sphere makes it necessary to maintain constant surveillance and to heighten public awareness of the appearance of new rotavirus strains. We describe the molecular epidemiology of circulating rotavirus strains after vaccine introduction. Methods We collected a total of 1070 stool samples from children with gastroenteritis from January 2013 to June 2013. The antigenic prevalence of rotavirus group A was distinguished using enzyme immunoassay. The G and P genotypes of enzyme immunoassay-positive samples were determined with reverse transcription-polymerase chain reaction and nucleotide sequencing analysis. Results Of the 1070 samples collected, 277 (25.9%) tested positive for rotaviruses by enzyme-linked immunoabsorbent assay. The most prevalent circulating genotype G was G1 (51.3%), followed by G2 (34.7%) and G9 (10.8%). The predominant type of genotype P was P[8] (66.1%), followed by P[4] (31.4%). In this study, nine genotypes were found. G1P[8] was the most prevalent (51.8%), followed by G2P[4] (30.5%), G9P[8] (9.9%), and G2P[8] (4.0%). Several unusual combinations (G1P[4], G3P[9], G3P[8], G4P[6], and G9P[4]) were also identified. Conclusion Molecular epidemiological knowledge of rotaviruses is critical for the development of effective preventive measures, including vaccines. These data will help us monitor the effectiveness of current rotavirus vaccines.

First report of iliacus abscess caused by Salmonella enterica serovar Othmarschen.

The non-typhoidal bacterium Salmonella enterica subspecies enterica serovar Othmarschen (Salmonella Othmarschen) is a rare human pathogen. Abscess formation due to non-typhoidal Salmonella infections is a very rare complication in this antibiotic era. We report the first case of iliacus abscess after a short period of gastroenteritis which was caused by non-typhoidal Salmonella enterica belonging to group C1, serovar Othmarschen in a patient without any underlying conditions. A young female presented in our hospital complaining of pain in right hip joint area. She gave a history of watery diarrhea 3 days before the onset of pain. On examination the patient was ill-looking and there was tenderness in the right hip joint area. S. enterica was identified using 16S rRNA gene amplification by PCR and serotyped to be serovar Othmarschen from the pus sample of iliacus abscess. This is the first reported case of iliacus abscess due to Salmonella serover Othmarschen infection. Our case suggests that S. enterica serovar Othmarschen can cause severe focal infections associated with gastroenteritis. The literature on the rare association of Salmonella enterica and abscess formation is reviewed.

Molecular Epidemiology of an Orientia tsutsugamushi Gene Encoding a 56-kDa Type-Specific Antigen in Chiggers, Small Mammals, and Patients from the Southwest Region of Korea

A phylogenetic analysis of Orientia tsutsugamushi was performed to elucidate its antigenic diversity in chiggers, small mammals, and patients. Between September 2014 and December 2016, a total of 3,816 chiggers were identified within nine species of four genera in the southwest region of Korea: Leptotrombidium scutellare (49.9%; 1,907/3,816), Leptotrombidium orientale (21.1%; 804/3,816), Leptotrombidium pallidum (12.4%; 474/3,816), Euchoengastia koreaensis (7.2%; 273/3,816), Leptotrombidium palpale (6.7%; 256/3,816), Neotrombicular gardellai (1.3%; 50/3,816), Leptotrombidium zetum (0.8%; 32/3,816), Walchia fragilis (0.5%; 18/3,816), and Neotrombicular japonica (> 0.1%; 2/3,816). Twelve chiggers (11 L. scutellare and one L. palpale) tested positive for O. tsutsugamushi by polymerase chain reaction and, except for 1 chigger (KY266830), were part of the Boryong strain cluster. Of the 413 small mammals that were analyzed for O. tsutsugamushi, Apodemus agrarius was the most common rodent species (89.5%; 370/413), followed by Crocidura lasiura (6.8%; 28/413) and Myodes regulus (3.6%; 15/413). The sequence identity of an O. tsutsugamushi sample obtained from the A. agrarius sample population belonged to the Saitama strain cluster. Furthermore, a phylogenetic analysis in 125 patients revealed four clusters (Boryong cluster: 82.4% [103/125], Karp: 13.6% [17/125], Kawasaki: 3.2% [4/125], and Saitama: 0.8% [1/125]). This study clarified the phylogenetic relationship for O. tsutsugamushi in chiggers, small mammals, and patients. The Boryong strain was the most common strain in chiggers and patients. In addition, various strains were identified, except for the Boryong strain, in the southwest region of Korea. Overall, the data presented here will be helpful for the establishment of prevention strategies for scrub typhus.

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.