Ji-Hyuk Park

An Outbreak of Foodborne Illness Caused by Enteroaggregative Escherichia coli in a High School in South Korea

In June 2013, a diarrheal outbreak occurred among high school students in Incheon, South Korea. We investigated the outbreak to identify the pathogen and mode of transmission. A case-control study using a self-administered questionnaire was conducted by local authorities and the Korean Centers for Disease Control and Prevention. Bacterial cultures of stool samples, environmental samples, and samples of preserved food items were prepared. PCR, serotyping, and pulsed-field gel electrophoresis (PFGE) were used to identify and characterize the outbreak-related pathogen. We identified 54 cases of gastroenteritis, with symptoms including diarrhea, abdominal pain, and nausea. None of the food items served in the high school cafeteria were significantly associated with illness, although the odds ratio for kippered trotters mixed with vegetables was relatively high (odds ratio: 2.92, 95% confidence interval: 0.62-13.69). Enteroaggregative Escherichia coli (EAEC) was isolated from this item and the stool samples from 22 symptomatic students and 4 asymptomatic food handlers. The PFGE patterns of EAEC isolated from these sources were indistinguishable. This outbreak was caused by EAEC, and kippered trotters mixed with vegetables, perhaps contaminated by asymptomatic food handlers, were linked to the outbreak. This case-control study highlights the importance of safe food preparation.

An outbreak of joint and cutaneous infections caused by non-tuberculous mycobacteria after corticosteroid injection

OBJECTIVES An outbreak of joint and cutaneous infections among patients who had been injected at a single clinic in South Korea was investigated. METHODS In this retrospective case-control study, 61 cases were diagnosed based on symptoms and signs of septic arthritis or cutaneous infection that developed after injections at the clinic between April and September 2012; 64 controls were investigated by administering questionnaires on risk factors and analyzing the clinic medical records. An environmental investigation was performed, and clinical specimens of the cases were analyzed by pulsed-field gel electrophoresis. RESULTS All cases were injected with triamcinolone. A greater number of triamcinolone injections (adjusted odds ratio 4.3, 95% confidence interval 1.5-12.1 for six or more visits, compared with one or two visits) was associated with the development of an infection. In the clinic, only the triamcinolone injection was prepared by mixing with lidocaine and normal saline, and an alcohol swab was prepared using boiled tap water by members of the clinic staff. Although injected medications and environmental cultures were not found to be responsible, a single strain of Mycobacterium massiliense was isolated from the affected sites of 16 cases. CONCLUSIONS Repeated injection of triamcinolone contaminated with NTM from the clinic environment may have caused this post-injection outbreak.

Work-Related Musculoskeletal Symptoms Among Dairy Farmers in Gyeonggi Province, Korea

OBJECTIVES The prevalence of work-related musculoskeletal symptoms (WMS) among Korean dairy farmers has not been investigated. The purpose of this study was to assess the prevalence of WMS and to evaluate the relationship between WMS and risk factors. METHODS Self-developed questionnaires including the questionnaire developed by the Korean Occupational Safety and Health agency (KOSHA) were used to investigate WMS among dairy farmers in Gyeonggi Province, Korea. We informed selected dairy farmers about the study and sent the questionnaires by registered mail. They visited a public health center nearby or a branch of public health center on the appointed date and skillful researchers identified or conducted the questionnaires by interview. We analyzed 598 (32.8%) of the 1824 dairy farmers. Multiple logistic regression was implemented to estimate the odds ratios of risk factors. RESULTS The mean age of the respondents was 50.4 +/- 8.7 years and the proportion of males was 63.0%. The prevalence of WMS at any site was 33.3%. The prevalence of neck WMS was 2.2%, shoulders 10.0%, arms/elbows 5.0%, hands/wrists/fingers 4.2%, low back 11.5%, and legs/feet 11.7%. The adjusted odds ratio of low back WMS for milking 4 or more hours per day was 4.231 (95% CI = 1.124 - 15.932) and statistically significant. Low back WMS (2.827, 95% CI = 1.545 - 5.174) was significantly decreased by education. CONCLUSIONS Low back WMS increased with milking hours and milking 4 or more hours per day was significantly associated with low back WMS. Low back WMS was significantly reduced with education. We hope that there will be increased attention about WMS in dairy farmers and the subject of future investigations.

Prevalence of Shiga toxin-encoding genes and risk factors among dairy farmers in Gyeonggi Province, Korea.

Abstract Background: Dairy farmers perform various types of work and are in direct contact with dairy cattle nearly every day. The purpose of this study was to assess the prevalence of Shiga toxin-encoding genes (stx) among dairy farmers and to evaluate the relationship between stx and risk factors. Methods: A questionnaire developed in-house was sent to dairy farmers in Gyeonggi Province, Korea by registered mail. Researchers obtained stool samples and identified or administered the questionnaires by interview. The stool samples were examined for stx genes by polymerase chain reaction. Results: Twenty (3.4%) of 589 stool samples from dairy farmers were stx-positive. The distribution of stx-positive stool samples revealed an increase in Shiga toxin-producing Escherichia coli infection with age, duration of work, and herd size. There was no association between stx-positive stool samples and type of work. For artificial insemination, taking a shower after work was significant, and the proportion of stx-positive dairy farmers increased as taking a shower after work decreased. Conclusions: Hygiene-related education to include taking a shower after sessions of artificial insemination should be considered. However, the stx-positive dairy farmers were small in number and the results should be interpreted with caution.

Epidemiological Features and Clinical Manifestations of Lyme Borreliosis in Korea during the Period 2005–2012

Lyme borreliosis is one of the most common tick-borne infections in the northern hemisphere. However, the epidemiological features and clinical manifestations of this disease in Korea are unknown. The present study is the first to investigate the characteristics of Lyme borreliosis in Korea. We traced suspected cases of Lyme borreliosis during the period 2005-2012. Of the 16 identified patients with the disease, 11 had acquired autochthonous infection within Korea, while 5 patients were infected outside Korea. The history of past exposure was investigated in 8 of the 11 patients with autochthonous infection; 5 of these 8 patients (62.5%) were suspected to have acquired the infection in the northeastern alpine region. Clinically, of 11 patients with autochthonous infection, 6 (54.5%) showed early skin manifestations, 4 (36.4%) showed neurological manifestations, and 1 (9.1%) showed acrodermatitis chronica atrophicans. In conclusion, Lyme borreliosis could be endemic in the northeastern alpine region of Korea, and neurological and early skin manifestations are likely to be the major clinical characteristics of autochthonous Lyme borreliosis in Korea.

Serologic Survey and Risk Factors for Coxiella burnetii Infection among Dairy Cattle Farmers in Korea

Background The zoonotic disease Q fever is caused by Coxiella burnetii and usually affects high-risk human populations. We conducted a serological survey of dairy cattle farmers in Korea to determine seroreactivity and identify risk factors for C. burnetii infection. Methods This cross-sectional study included 1,824 of 7,219 dairy cattle farms (25.3%) in the study region. The selected dairy cattle farmers visited the nearest public health centers or branches with completed questionnaires. Serum samples from the farmers were tested using an indirect immunofluorescence assay to detect phase II C. burnetii immunoglobulin (Ig) G or M antibodies. Results A total of 1,222 dairy cattle farmers from 784 dairy cattle farms (43.0%) participated in this study, and 11.0% (134/1,222) exhibited seroreactivity, defined as a phase II antigen IgG or IgM titer ≥ 1:16. In the multivariate analysis, male sex, residence in Gyeonggi Province, a larger herd size, and ocular/oral contact with birth products during calf delivery were significantly associated with a higher risk of C. burnetii infection. Furthermore, the risk was significantly lower among farmers who always wore protective gloves while cleaning cattle excretion, compared to those who sometimes or rarely wore protective gloves. Conclusion Dairy cattle farmers should exercise caution by avoiding ocular/oral contact with birth products during calf delivery and by using protective equipment (including gloves).

Necessity of a Surveillance System for Tick-borne Encephalitis

Dear Editor: With great interest, I have gone through the paper titled, “Prevalence of tick-borne encephalitis virus in ixodid ticks collected from the Republic of Korea during 2011‒2012,” by Yun et al [1]. Yun et al [1] reported that the minimum infection rate (MIR) of tick-borne encephalitis (TBE) from a tick was 0.08%. The MIR from Haemaphysalis longicornis, a tick species that constitutes most collected ticks, was 0.06%. In another paper that also studied the MIR of severe fever with thrombocytopenia syndrome (SFTS) from H. longicornis reported a MIR of 0.46% [2]. In South Korea, the first case of a patient with SFTS was reported in 2013 [3]; the number then gradually increased to 79 cases in 2015 with the initiation of a surveillance protocol [4]. A simple comparison between the MIRs of TBE and those of SFTS from H. longicornis shows that the number of patients with TBE is one-eighth of the number of patients with SFTS. However, no additional cases were reported from 2011 after the legal designation of TBE as an infectious disease, up to October 2016. This may be due to a difference in transmission route or pathogenicity, but TBE is certainly under-reported in Korea because of its unfamiliarity. Therefore, TBE surveillance by health authorities should be strengthened and awareness among primary-care physicians by education and public relations about TBE should be increased.

The direction of restructuring of a Korea field epidemiology training program through questionnaire survey among communicable disease response staff in Korea

We used a survey about the need for an educational training of infectious disease response staff in Korea Centers for Disease Control and Prevention (KCDC) and officer in metropolitan cities and provincial government to conduct field epidemiological investigation. The survey was conducted from January 25 to March 15, 2016. A total of 173 participants were selected from four different groups as follows: 27 clinical specialists, 22 Epidemic Intelligence Service (EIS) officers, 82 KCDC staff, and 42 local health department officials. Results revealed that 83% of KCDC staff and 95% of local health department officials agreed on the need for educational training to strengthen capability of personnel to conduct epidemic research and investigation. The level of their need for training was relatively high, while self-confidence levels of individuals to conduct epidemic research and investigation was low. It was concluded that there was a need to develop training programs to enhance the ability of public health officials, EIS officers, KCDC staff, and local health department personnel to conduct epidemic research and investigation.

Analysis of Kudoa septempunctata as a cause of foodborne illness and its associated differential diagnosis

1 Dear Editor, With great interest, I read the paper entitled, “Analysis of Kudoa septempunctata as a cause of foodborne illness and its associated differential diagnosis”, written by Lee [1], which was published in Epidemiology and Health in March 2017. The pathogenicity of K. septempunctata was advocated for in an article written by Kawai et al. [2] in Japan, but this proposal was argued against in 2 studies conducted by Ahn et al. [3] and Jang et al. [4] in South Korea (hereafter Korea) using suckling mice. However, there are a few differences among these studies that should be noted. First, the study by Kawai et al. [2] used K. septempunctata spores isolated from the cases of foodborne illness outbreaks, while the other studies [3,4] used K. septempunctata spores collected from commercial fish farms. Second, the genotypes of K. septempunctata can be classified as sequence type1 (ST1), ST2, and ST3. The ST1 and ST2 genotypes are mostly found in Japan, while the ST3 genotype is most commonly found in Korea [5]. No information was provided about the genotype of K. septempunctata in the study performed in Japan [2]. The 2 studies performed in Korea [3,4] assessed the pathogenicity of the ST3 genotype. Thus, these findings do not demonstrate the lack of pathogenicity of the ST1 and ST2 genotypes. According to the study by Lee [1] in Korea, 11 foodborne outbreaks in 2015 provide support for the possibility of K. septempunctata pathogenicity. However, there are limitations to this argument because those outbreak investigations were case series studies, not case-control studies or retrospective cohort studies. In Japan, among 24 foodborne outbreaks with unknown causes, 4 outbreaks were significantly associated with the consumption of olive flounder (Paralichthys olivaceus). Among those 4 outbreaks, K. septempunctata was isolated from at least 1 foodborne outbreak [2]. In Korea, K. septempunctata has not been included as a causative agent of foodborne outbreaks in the 2016 guidelines for water and foodborne diseases prevention and control [6]. However, K. septempunctata was included as a causative agent of food poisoning in the 2017 food safety administrative guidelines [7]. To obtain more epidemiological evidence of pathogenicity, further efforts are needed to perform a case-control study or cohort study of foodborne outbreaks relating to the consumption of olive flounder. Moreover, more stringent traceback investigations are needed to determine the production and distribution chain of olive flounder.

Epidemiological Investigation on an Outbreak of Norovirus Infection at a High School in Gyeongju City, 2009

= Abstract = Objectives: An outbreak of norovirus occurred at a high school in Gyeongju city in 2009. An epidemiological investigation was carried out to examine the infection source and the transmission route of norovirus, and to prevent a recurrence. Methods: A questionnaire survey was conducted for 520 male students and 8 food handlers. Rectal swabs were examined in 21 symptomatic students and the 8 food handlers by Gyeongsangbukdo Government Public Institute of Health & Environment, and an environmental investigation was performed. A case-control study was used to evaluate the association between risk factors and disease. Results: The attack rate was 21.3% (111/520) between January 29 and February 10, and norovirus GⅡ was isolated from 12 of 21 students. Food handlers had no symptoms and their stool samples were negative. The case-control study revealed that seasoned soy bean sprouts {odds ratio (OR): 2.542, 95% CI=1.315-4.915} and drinking water from the purifiers in the cafeteria (OR: 2.854, 95% CI=1.107-7.358) supplied on February 3 were significant risk factors for the outbreak. Water pipes and waste pipes were located in the same place where was filled with some water and trace of high water level was detected. Conclusions: The major risk factors for this norovirus outbreak were presumed to be the contaminated seasoned soy bean sprouts and drinking water from the purifiers in the cafeteria. More strict personal and environmental hygiene need to be enforced to prevent such outbreaks.