Hepatitis A Outbreak in a Facility for the Disabled, Gyeonggi Province, Korea: An Epidemiological Investigation.

OBJECTIVES: The number of cases of hepatitis A virus (HAV) infections has sharply increased in Korea, especially among young adults. In this study, an HAV outbreak in a facility for disabled people was investigated, and we found epidemiological differences both between 2 different generations and between generally abled and disabled groups. METHODS: We analyzed the incubation period and attack rate of an HAV outbreak and investigated the prevalence of HAV antibodies among the staff and residents of a facility for the disabled. We performed a retrospective cohort study during the HAV outbreak, which lasted from February 8 to 25, 2019, including examinations of HAV antibody tests and post-exposure HAV vaccination for the staff or residents of the facility. RESULTS: There were 9 confirmed cases in 2 staff members and 7 residents. Among 53 people (30 staff and 23 residents), except for the 9 confirmed cases and 1 staff member with a known history of HAV infection, HAV seroprevalence was seen in 16.7% of the staff under 40 years of age and 95.2% of those over 40 years of age, while the corresponding rates in the residents were 0.0% and 58.8%, respectively. CONCLUSIONS: This result implies that it is necessary to prioritize HAV vaccination for vulnerable groups and workers of residential care facilities.

Foodborne Illness Outbreaks in Gyeonggi Province, Korea, Following Seafood Consumption Potentially Caused by Kudoa septempunctata between 2015 and 2016.

OBJECTIVES: Investigations into foodborne illness, potentially caused by Kudoa septempunctata, has been ongoing in Korea since 2015. However, epidemiological analysis reporting and positive K septempunctata detection in feces in Korea has been limited. The aim of this study was to provide epidemiologic data analysis of possible food poisoning caused by K septempunctata in Korea. METHODS: This study reviewed 16 Kudoa outbreak investigation reports, including suspected cases between 2015 and 2016 in Gyeonggi province, Korea. Suspected Kudoa foodborne illness outbreak was defined as "evidence of K septempunctata in at least one sample." The time and place of outbreak, patient symptoms and Kudoa (+) detection rate in feces was analyzed. RESULTS: Kudoa foodborne illness outbreaks occurred in most patients in August (22.6%) and in most outbreaks in April (25%). The attack rate was 53.9% and the average attack rate in patients who had consumed olive flounder was 64.7%. The average incubation period was 4.3 hours per outbreak. Diarrhea was the most common symptom which was reported by 91.5% patients. The Kudoa (+) detection rate in feces was 69.2% of cases. CONCLUSION: Monthly distribution of Kudoa foodborne illness was different from previous studies. The Kudoa (+) detection rate in feces decreased rapidly between 25.5 and 28.5 hours of the time interval from food intake to epidemiologic survey. To identify effective period of time of investigation, we believe additional study with extended number of cases is necessary.

Outbreak investigation of pertussis in an elementary school: a case-control study among vaccinated students.

PURPOSE: A pertussis patient from an elementary school, in Gyeonggi Province, Korea, was notified to public health authority on July 25, 2017. Epidemiologic investigation was conducted to identify the magnitude, possible source of infection and risk factors for this outbreak on August 17, 2017. MATERIALS AND METHODS: A case was defined as the school student experiencing cough for more than two weeks with or without paroxysmal, whoop, or post-tussive vomiting. Control was defined as the student polymerase chain reaction-negative at the school. School based surveillance was implemented to identify additional cases. RESULTS: From June 29 to August 27, 2017, nine patients of pertussis were identified from an elementary school. Among nine cases, eight were confirmed by polymerase chain reaction positive. All cases had cough, one (11%) had post-tussive vomiting, and one (11%) had fever. Eight cases had macrolide for 7 days in outpatient clinic, and one case admitted in a hospital. There was no significant difference of demographic factors including gender (p=0.49), age group (p=0.97), number of series of vaccination of pertussis (p=0.52), the number of participation of after school activity (p=0.28), and the time elapsed since last vaccination (p=0.42). However, we found the history of contact within the classroom or after-school activity was only the independent risk factor among all the demographic factors collected (odds ratio, 63.61; 95% confidence interval, 4.35 to 930.79). CONCLUSION: The contributing factor for transmission is associated with the case-contact. Immediate identification of pertussis with use of appropriate diagnostic test may help to avoid a large number of cases.