Hyobi Kim

Epidemiological Aspects of Human Brucellosis and Leptospirosis Outbreaks in Korea

In order to compare the epidemiological aspects of human brucellosis (HB) and human leptospirosis (HL) outbreaks in Korea, we have analyzed the current state both of the disease incidence and related risk factors. A total 651 cases of HB occurred between 2001 and 2010 in Korea, and the average incidence rate per 100,000 populations was 0.15. A total 1,153 of HL cases occurred during the same period, and its rate was 0.24. While most of the HB prevalence occurred in the whole year round, prevalence in summer was more prominent for HB (p < 0.01), while outbreaks in autumn was more frequent for HL (p < 0.01). Geographical distribution HB cases were eastern and western regions of the rural (88.6% of total) in the Korean peninsula, showing higher outbreaks than other areas, while HL occurred in easterly regions (64.5%). Significantly more males were infected in both HB (86.8%) and HL (59.5%) than those of females in both HB (13.1%) and HL (41.1%), respectively (p < 0.01). The distribution by age groups were different between HB and HL, while the outbreaks over 62.1% of the cases of HB occurred in 40- to 59-year-old age group, and that of HL was clearly showing a high incidence in the elderly age over 60-year-old (59.6%) (p < 0.01). In both diseases, elderly people especially in famers showed a very high incidence rate (57.9% of HB and 52.2% of HL), which is possible due to increased outdoor activities and a decreased number of young people in those areas. The occupational distribution of HB cases was famers, veterinarians, dairyman and others, and those of HL cases were broad. In conclusion, the difference between HB and HL risk factors reflects the different influence of host/vector, climate, and geographical and environmental characteristics in the epidemiological patterns. Keywords Human brucellosis and leptospirosis; Epidemic aspects; Risk factors

Seroprevalence of Coxiella burnetii in cattle and farm- raised deer in Korea

Q fever, caused by Coxiella burnetii, is a worldwide zoonosis that affects not wild animals but domestic animals throughout the world, except in New Zealand. Domestic ruminants are considered to be a major infection source of Q fever in humans. However, few studies on the prevalence of Q fever in humans or animals in Korea have been conducted. Thus, the aim of this study was to investigate the seroprevalence of Q fever in meat cattle and deer. Blood samples were collected from 1634 ruminants: 1000 cattle, 604 wapiti, and 30 sika deer. The blood samples were analyzed with CHEKIT Q fever ELISA kits. Thirteen of 1000 (1.3%) cattle, 10 of 604 (about 1.7%) wapiti, and 0 of 30 (0%) sika deer had antibodies against C. burnetii. The prevalence of Q fever in this study was quite low. However, the public health implications of these findings are important, because they indicate that seropositive animals that are asymptomatic may be shedding C. burnetii consistently. This condition could increase the risk of Q fever infection in Korea, especially because many Koreans habitually consume raw meat and drink deer blood.

Inactivation of Salmonella on Eggshells by Chlorine Dioxide Gas

Microbiological contamination of eggs should be prevented in the poultry industry, as poultry is one of the major reservoirs of human Salmonella. ClO2 gas has been reported to be an effective disinfectant in various industry fields, particularly the food industry. The aims of this study were to evaluate the antimicrobial effect of chlorine dioxide gas on two strains of Salmonella inoculated onto eggshells under various experimental conditions including concentrations, contact time, humidity, and percentage organic matter. As a result, it was shown that chlorine dioxide gas under wet conditions was more effective in inactivating Salmonella Enteritidis and Salmonella Gallinarum compared to that under dry conditions independently of the presence of organic matter (yeast extract). Under wet conditions, a greater than 4 log reduction in bacterial populations was achieved after 30 min of exposure to ClO2 each at 20 ppm, 40 ppm, and 80 ppm against S. Enteritidis; 40 ppm and 80 ppm against S. Gallinarum. These results suggest that chlorine dioxide gas is an effective agent for controlling Salmonella, the most prevalent contaminant in the egg industry.

Intrinsic dorsoventral patterning and extrinsic EGFR signaling genes control glial cell development in the Drosophila nervous system

Dorsoventral patterning and epidermal growth factor receptor (EGFR) signaling genes are essential for determining neural identity and differentiation of the Drosophila nervous system. Their role in glial cell development in the Drosophila nervous system is not clearly established. Our study demonstrated that the dorsoventral patterning genes, vnd, ind, and msh, are intrinsically essential for the proper expression of a master glial cell regulator, gcm, and a differentiation gene, repo, in the lateral glia. In addition, we showed that esg is particularly required for their expression in the peripheral glia. These results indicate that the dorsoventral patterning and EGFR signaling genes are essential for identity determination and differentiation of the lateral glia by regulating proper expression of gcm and repo in the lateral glia from the early glial development. In contrast, overexpression of vnd, msh, spi, and Egfr genes repressed the expression of Repo in the ventral neuroectoderm, indicating that maintenance of correct columnar identity along the dorsoventral axis by proper expression of these genes is essential for restrictive formation of glial precursor cells in the lateral neuroectoderm. Therefore, the dorsoventral patterning and EGFR signaling genes play essential roles in correct identity determination and differentiation of lateral glia in the Drosophila nervous system.

Effect of Chlorine Dioxide Gas Application to Egg Surface: Microbial Reduction Effect, Quality of Eggs, and Hatchability

Abstract Controlling of microorganisms in the industrial process is important for production and distribution of hatching and table eggs. In the previous study, we reported that chlorine dioxide (ClO2) gas of a proper concentration and humidity can significantly reduce the load of Salmonella spp. on eggshells. In this study, we compared microbial reduction efficacy on egg’s surface using hatching eggs and table eggs, internal quality of table eggs, and hatchability after both the conventional method (washing and UV expose, fumigation with formalin) and ClO2 gas disinfection. Application of 40 ppm ClO2 gas to the table and hatching eggs, respectively, reduced the aerobic plate count (APC) with no statistical difference compared with the conventional methods. Additionally, we didn’t observed that any significant difference in albumin height, Haugh unit (HU), and yolk color, this result confirms that 40 ppm ClO2 had no effect on the internal quality of the table eggs, when comparing with the UV treatment method. The hatchability of hatching eggs was not statistical different between formaldehyde fumigation and 80 ppm ClO2 gas treatment, though the value was decreased at high concentration of 160 ppm ClO2 gas. From these results, we recommend that ClO2 gas can be used as a safe disinfectant to effectively control egg surface microorganisms without affecting egg quality.

Method Development for Determination of Multi-Mycotoxins in Chicken Liver and Kidney Tissues by LC-MS/MS

Mycotoxins are secondary metabolites produced by molds, such as Aspergillus, Fusarium and Penicillium, that have adverse effects on animals and humans. Aflatoxin, ochratoxin, zearalenone, fumonisin and deoxynivalenol are the mycotoxins of greatest agro-economic importance and cause acute disease called mycotoxicoses. Mycotoxicosis in poultry birds results in decreased meat/egg production, immunosuppressant, and hepatotoxicosis. Some of toxins or their metabolites may be retained in animal or human tissues and induce health problems. This study was designed to develop a sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the simultaneous detection and quantification of mycotoxins, such as aflatoxin , aflatoxin , ochratoxin A, zearalenone, fumonisin B and deoxynivalenol, in chicken liver and kidney tissues. The mycotoxins were extracted and purified using modified QUECHERS methods, separated by LC and detected by an electrospray ionisation interface (ESI) and tandem MS. Good precision and linearity were observed for most of six mycotoxins. The recovery test for each mycotoxin in liver and kidney tissues mostly indicated good average recovery rates between 80.94% and 98.10% and the coefficient of variation mostly under 13.78%, except for aflatoxin and fumonisin . The limit of detection (LOD) for six mycotoxins was in liver tissues and in kidney tissues. The quantification limits (LOQ) for 6 mycotoxins were in the range in liver tissues and in kidney tissues, respectively. The developed multi-mycotoxin method in this study permits simultaneous, simple, and rapid determination of several co-existing mycotoxins in chicken liver and kidney tissues.