Seok-Ju Yoo

Seroprevalence and risk factors of brucellosis among slaughterhouse workers in Korea

OBJECTIVES The incidence of zoonoses in Korea has increased recently. However, the study of high risk groups for zoonoses has not been conducted to date in Korea. Thus, we did this study to obtain data on brucellosis among slaughterhouse workers in Korea. METHODS We evaluated the structure of slaughterhouses and the process of slaughtering by reviewing the relevant literature and doing field studies. We visited 73 slaughterhouses and 62 residual products handle houses across the country. In addition, we conducted a questionnaire survey of the work activities, and obtained blood samples in order to determine the seroprevalence and risk factors of brucellosis. The titers of brucellosis antibodies were measured using the standard tube agglutination test (SAT). We diagnosed subjects as seropositive for Brucellosis if the titers were more than 1:160. The data collected was evaluated using SPSS ver. 17.0. RESULTS We included 1,503 subjects and obtained 1,482 blood samples among them: 849 workers involved in slaughtering, 351 handlers of residual products, 190 inspectors and their assistants, and 92 grading testers and their assistants. The seroprevalence of brucellosis among the slaughterhouse workers was 0.8% (95% CI=0.4-1.5). Broken down, the seroprevalence of brucellosis among the workers involved in slaughtering was 0.7% (95% CI=0.3-1.6), the handlers of residual products was 1.7% (95% CI=0.7-3.9) respectively. Risk factors for contracting brucellosis among slaughterhouse workers were being splashed with cattle blood around the mouth, cattle secretions around the body and not putting on protective apron while at work. CONCLUSIONS An educational program is needed for high risk groups on zoonoses about the prevention of infection. Thus, effective working guidelines for workers who participate in the slaughter of animals must be developed in order to protect them from zoonoses.

Cross-sectional analysis of the seropositivity and risk factors of Toxoplasma gondii infection among veterinarians, in relation to their public professional activities.

Toxoplasma gondii is a zoonotic pathogen that can infect most warm-blooded animals and humans. Although numerous epidemiological studies of T. gondii have been published, very limited data exist on the prevalence of T. gondii infection among veterinarians. In this study, a survey was used to analyze the seropositivity of and risk factors for T. gondii infection among public veterinarians (PV) and veterinarians in veterinary service laboratories (VVSL). Blood samples were collected from individuals in both groups and examined by enzyme immunoassay (EIA). A questionnaire survey on work activities and personal dietary habits was also conducted. The positive rate for specific anti-T. gondii IgG antibody was 8% overall, comprising 13.4% in the PV group and 5.5% in the VVSL group. The seropositivity of T. gondii infection in the PV group was significantly related to involvement with the enforced destruction and contact with animals that were infected with zoonotic pathogens. Consumption of raw pork and drinking unboiled groundwater were also critical dietary risk factors for seropositivity for T. gondii infection. This is the first study of the factors that contribute to T. gondii infection among veterinarians with public professional activities in Korea. Further preventive educational programs for veterinarians with public professional activities are necessary to prevent exposure to T. gondii infection in this population.

Green Tobacco Sickness Among Tobacco Harvesters in a Korean Village

Background Green tobacco sickness (GTS), an occupational disease in tobacco harvesters, is a form of acute nicotine intoxication by nicotine absorption through the skin from the wet green tobacco plant. We carried out a questionnaire survey and measured cotinine concentration, the metabolic product of nicotine, to determine the prevalence, incidence, and risk factors of GTS in Korean tobacco harvesters. Methods We measured cotinine concentrations, and administered a questionnaire survey to tobacco harvesters in Cheongsong-gun, Gyeongsangbuk-do, Korea. We repeatedly measured urine cotinine concentration five times with a questionnaire survey. Results Cotinine concentration at dawn was significantly higher than that at other times; it was significantly lower during the nonharvesting period than during the harvesting period. However, little change in cotinine concentration was detected in the daytime during the harvesting period. Study participants included 20 men and 20 women. The prevalence of GTS was 37.5% and was significantly higher in women than in men (55.0% vs. 20.0%, p < 0.01). GTS incidence according to number of workdays was 3.4 occurrences/100 person days. Conclusion In this study, nicotine exposure and metabolism were experimentally determined from the time of cotinine exposure, and biological monitoring was performed in each season. In the future, this information may be valuable for medical decision-making in GTS prevention.

Seroreactivity to Q Fever Among Slaughterhouse Workers in South Korea

Objectives Q fever is a zoonotic disease that occurs worldwide; however, little is known about its prevalence in South Korea. We attempted to determine the prevalence of Q fever seroreactivity among Korean slaughterhouse workers and the risk factors for seroreactivity according to the type of work. Methods The study was conducted among 1503 workers at a total of 73 slaughterhouses and 62 residual-product disposal plants. During the study period, sites were visited and surveys were administered to employees involved in slaughterhouse work, and serological tests were performed on blood samples by indirect immunofluorescence assays. Serological samples were grouped by job classification into those of slaughter workers, residual-product handlers, inspectors and inspection assistants, and grading testers and testing assistants. Employee risk factors were analyzed according to the type of work. Results Out of 1481 study subjects who provided a blood sample, 151 (10.2%) showed reactive antibodies. When these results were analyzed in accordance with the type of work, the result of slaughter workers (11.3%) was similar to the result of residual-product handlers (11.4%), and the result of inspectors and assistants (5.3%) was similar to the result of grading testers and assistants (5.4%). Among those who answered in the affirmative to the survey question, “Has there been frequent contact between cattle blood and your mouth while working?” the proportions were 13.4 and 4.6%, respectively, and this was identified as a risk factor that significantly varied between job categories among slaughterhouse workers. Conclusions This study found a Q fever seroreactivity rate of 10.2% for slaughterhouse workers, who are known to be a high-risk population. Contact with cattle blood around the mouth while working was the differential risk factor between job categories among slaughterhouse workers.

Awareness on Zoonoses among Pig Farmers in Korea

We visited four regional spots (Gyeongsangnam-do, Gyeongsangbuk-do, Jeollanam-do, and Chungcheongnam-do) where the self education programs of Korea pork producers were convened. We conducted a questionnaire survey of the general, work-related characteristics and the awareness on zoonoses among 278 pig farmers.

Analysis of the change of health status among the republic of Korea air force soldiers during military service.

Objectives: The aim of this study was to investigate whether the health status of Republic of Korea Air Force (ROKAF) soldiers changed after one year of military service. Methods: We selected 483 ROKAF soldiers from the 11 749 recruits who participated in the 2011 physical examination. The selected soldiers underwent another physical examination in 2012 for advancement to senior airman. Data from 2011 and 2012 were merged. To collect data on lifestyle, a questionnaire was sent to all included subjects via the military intranet e-mail service. Results: The percentage of recruits with an abnormal alanine transaminase level (normal range <40 IU/L) decreased from recruitment (13.7%) to the following year (2.7%). Moreover, the percentage of obese soldiers (body mass index ≥25 kg/m2) decreased from recruitment (20.5%) to the following year (10.4%). There was a significant change in mean duration of exercise carried out each day before (0.8±1.3 hours) and after (1.0±0.7 hours) joining the ROKAF service. Conclusions: These ROKAF soldiers were generally in good health before and after joining the armed service. After one year of military service, the health status of most soldiers improved, especially with respect to body mass index and alanine transaminase level.

Epidemiological Investigation of an Outbreak of Salmonellosis in Gyeongju, Korea

Objectives A salmonellosis outbreak occurred within a community of Gyeongju residents who ingested catered food from a wedding in June 2009. We aimed to epidemiologically investigate the probable vehicle of the infection. Methods We conducted a retrospective cohort study on 34 local residents who ingested the wedding food. Results Among the 34 residents, 31 (91.2%) reported symptoms of infection after eating the food. Among all of the wedding foods, pan-fried foods were highly associated with the diarrheal attack rate. On bacteriological examination, Salmonella species were detected in the pan-fried foods among the leftover foods and in 17 of the 31 stool specimens from the cases. There were five different types of pan-fried foods, but the onset of symptoms was independent of the ingredients used. We found that the pan-fried food was prepared at a food store in Seoul and that eggs were a common ingredient. Conclusions The major cause of the salmonellosis in this population was presumed to be the pan-fried food prepared with contaminated eggs. These food items might have been partially undercooked because of their irregular shape, which allowed the Salmonella species to survive and multiply before ingestion.

Anti-Shiga toxin immunoglobulin G antibodies in healthy South Korean slaughterhouse workers

Abstract Background: Slaughterhouse workers are in direct contact with cattle nearly every day. The purpose of this study was to survey the presence and distribution of anti-Shiga toxin 1 (Stx1) immunoglobulin G (IgG) in slaughterhouse workers, enabling a study of the serologic response to this toxin while working in an area at high-risk of Stx-producing Escherichia coli (STEC) infection. Methods: One thousand seven hundred and twenty-nine serum samples from healthy slaughterhouse employees were collected and surveyed by indirect enzyme-linked immunosorbent assay (ELISA). Results: Among the 5 slaughterhouse positions, slaughterers had the highest distribution of anti-Stx1 IgG values by an ELISA. Based on the ELISA values, 25% (433/1729) of the workers had anti-Stx1 IgG. Slaughterers, residual products handlers, inspectors, livestock hygiene controllers, and grading testers had anti-Stx1 IgG-positive rates of 28%, 25%, 20%, 19%, and 17%, respectively. The ELISA values of anti-Stx1 IgG increased with increases in the number of years worked by slaughterers, but not by residual products handlers, inspectors, livestock hygiene controllers, or grading testers. Conclusions: From these results, slaughterhouse workers are healthy and asymptomatic; slaughterers in particular are at high-risk for STEC exposure.

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).

Awareness and Work-Related Factors Associated with Scrub Typhus: A Case-Control Study from South Korea

This study aimed to examine the awareness and the work-related factors associated with scrub typhus to provide data essential for evidence-based preventive strategies. A community-based case control study was carried out in the rural areas of Gyeongsangbuk-do, South Korea. Confirmed cases of scrub typhus (n = 57) were based on laboratory tests performed by the Korean Centers for Disease Control and Prevention (KCDC), 114 matched neighborhood controls, age (±6 years), gender and area of residence in the Gyeongsangbuk-do of South Korea. These cases were contracted over the 12-month period of January to December 2015. Overall, 61.4% cases and 79.8% of the control group had heard about scrub typhus. Cases were less aware about the fact that mites are mainly found in the bushes and that long sleeves and full-length pants and boots helped prevent scrub typhus. However, more were aware of the eschar lesion as a characteristic sign of scrub typhus. Work related risk factors such as having a wetland or puddles of water surrounding the house, dry field farming and working in the livestock industry were significantly associated with the scrub typhus. Health promotion strategies, such as creating general awareness, personal protection methods and improving personal hygiene and environmental sanitation in collaboration with relevant sectors, are recommended to reduce the burden of scrub typhus. Further intervention studies on awareness and behavioral and environmental modifications are required to investigate the effectiveness of such interventions.