In recent years, the national surveillance network reported the isolation of Enterobacter sakazakii and coliform from powdered infant formula (PIF). PIF means a breast-milk substitute specially manufactured to satisfy the nutritional requirements of infants during the first month. PIF is not sterile infant food and may be intrinsically contaminated with pathogens, such as E. sakazakii and Salmonella enterica that can cause serious illness in infants. Intrinsic contamination of PIF with E. sakazakii and S. enterica has been a cause of infection and illness in infants. E. sakazakii is an opportunistic pathogens and more commonly found than S. enterica in manufacturing environment. Even low levels of contamination of E. sakazakii and S. enterica in PIF were considered to be a risk factor. Enterobacteriaceae showed the high prevalence and some Enterobacteriaceae causing disease were detected. The infant food industry should be encouraged to reduce the concentration and prevalence of E. sakazakii in both the manufacturing environment and PIF. The presence of these microorganisms in PIF may occur as a results of contamination through ingredients during PIF manufacturing process and from the processing environment during packaging. In order to ensure that ingredients and packaging materials are microbiologically suitable, PIF manufacturer need to be selection of supplier according to stringent criteria (e.g. HACCP, good hygienic practices) and testing of ingredients especially colostrum. In conclusion, it is continually necessary to monitor the potential pathogens and reduce them to improve the microbial quality of non-sterilized PIF.
To determine the prevalence of Campylobacter jejuni and Campylobacter coli in meats, a total of 4,161 samples (1,953 domestic and 2,208 imported) were collected from 304 slaughterhouses nationwide and registered cold storages for imported meats in Korea during 2005～2009. The isolation rates of C. jejuni and C. coli in domestic beef, pork, chicken and duck meats were 0.1% (1/630), 0% (0/630), and 0.1% (1/644), 0% (0/644) and 20.5% (125/609), 10.2% (62/609) and 25.7% (18/70), 20.0% (14/70), respectively. In the case of imported meats, C. jejuni were isolated from 0.1% (1/943) and 15.2% (83/546) of pork and chicken meats, respectively, and C. coli were detected only from 4.8% (26/546) of chicken meats. Neither C. jejuni nor C. coli were detected from imported beef, and C. coli were also not detected from imported pork. In conclusion, chicken meats had much higher rate of contamination with Campylobacter compared to beef and pork. Therefore, HACCP system that is now mandatory for slaughterhouses should be actively practiced for safe and sanitary processing, handling, and marketing of chicken meats. In addition, all critical control points should be determined by processing procedures at processing plants as well as farms and slaughterhouses, and monitoring should be carried out at regular intervals.
Guillain-Barré syndrome (GBS) is the most common cause of acute flaccid paralysis and autoimmune polyradiculoneuropathy. Campylobacter jejuni is the most commonly identified infectious trigger for GBS. A sialic-acid containing lipopolysaccharide (LPS) of Campylobacter is thought to be involved in the triggering of GBS. The galE (UDPgalactoset- epimerase) gene of Campylobacter spp. is involved in the synthesis of LPS. In this study, we detected the galE gene in Campylobacter spp. responsible for triggering the onset of GBS. The PCR assay detected the presence of the gene in 14 of the 25 (56%) Campylobacter isolates from domestic chicken, 20 of the 28 (71.4%) Campylobacter isolates from imported chicken and 50 of the 51 (98%) Campylobacter isolates from human clinical samples. Also, the specific 497-bp region of galE sequence in Campylobacters responsible for triggering the onset of GBS was amplified from GBS patient. These results could provide evidence of the first GBS-related C. jejuni infection in Korea.
Vibrio parahaemolyticus (V. parahaemolyticus) has been recognized as a significant food-borne pathogen around the world. In this study, we investigated the prevalence and antimicrobial resistance of V. parahaemolyticus isolated from raw fishes. A total of 64 samples of raw fishes purchased from a traditional seafood market in Seoul, Korea. were examined for the presence of V. parahaemolyticus using intestines, gills, and fins. Twenty five grams of all samples were enriched in 225ml of alkaline peptone water at 37℃ for 24h and then streaked onto thiosulfate citrate bile sucrose agar. Suspected colonies were inoculated into triple sugar iron agar for biochemical screening test and were finally confirmed with API 20NE strip. Antimicrobial resistance tests were performed with disc diffusion method in accordance with National Committee for Clinical Laboratory Standard. Thirty three V. parahaemolyticus strains were isolated from raw fishes among 33 out of 64 (51.6%). Among 33 isolates, 16 isolates (48.5%) were resistant to ampicillin, 7 isolates (21.2%) were resistant to amikacin, and all isolates were not resist to other antibiotics such as amoxicillin & clavulanic acid, sulfamethoxazole & trimethopenem, ciprofloxacin, cefotaxime and cefepime. Although the prevalence of V. parahaemolyticus was high in raw fishes compared to other studies, antimicrobial resistance rate of the isolates was relatively low. These results could be useful information for risk assessment of V. parahaemolyticus in raw fishes.
This paper describes an investigation of an outbreak of foot-and-mouth disease (FMD) in Republic of Korea in January 2010. In this paper, we investigated introduction to the index farm from overseas countries, transmission from index farm to other outbreak farms. The introduction factors were divided direct, indirect factors or airborne spread factor. Based on the epidemiological data, clinical information and other data, in these introduction factors, it was likely that outbreak of FMD in index farm was due to international goods or employees from overseas countries (including China). There were other suggested causes in index farm. But it was less likely that outbreak of FMD in index farm have occurred by other causes. The transmission factors from index farm to other farms were also divided direct, indirect factors or airborne spread factor. In these transmission factors it was possible to make assumptions from index farm to other outbreak farms that the FMD virus was transmitted through animal treatment, persons concerned and persons (who were) attended farmers’ assembly.
Since there had been the first human outbreak of novel influenza A/H1N1 in Mexico, it has become pandemic throughout the world. In the Republic of Korea, the first human case was on May, 2009 and National Veterinary Research and Quarantine Service (NVRQS) has started monitoring novel influenza A/H1N1 on domestic swine farms. The first positive case was detected on 14, Dec, 2009 and until now, we have had total 17 positive cases. From the first case, we did epidemiological investigation on introduction and transmission of virus to pigs. We have concluded that virus had been introduced from humans to pigs, possibly from October to November, 2009 in our country. There were direct and indirect factors including the vehicles transporting veterinary medicine, feed, etc. related to transmission of virus from farm to farm. However, breeding pigs seem to be extrinsic to transmitting factors. Upon the epidemiological investigation, the off-limits of visitors to farms and the disinfection is thought to be critical for blocking the introduction and transmission of novel influenza A/H1N1. In addition, collecting and analyzing the genetic informations of influenza virus is important for predicting and handling the new pandemic influenza in the future.
Although several enteric viral pathogens including the porcine groups A, B and C rotaviruses (PGARV, PGBRV, and PGCRV), sapovirus (PSaV), and torovirus (PToV) are known to cause endemic diarrheas in weaning and post-weaning piglets, their precise prevalence in Korea is not clear. Therefore, we examined 1,222 diarrhea stools obtained from 627 farms during 2004～2009 by RT-PCR and/or nested PCR for evaluating their precise prevalence in Korea. PGARV was the predominant pathogen during 2004～2007 but its prevalence was markedly reduced during 2008～2009. PGBRV infections caused endemic diarrhea during 2004～2007, but was hardly detected during 2008-2009. PGCRV was detected at 27.0%, 14.5%, 42.4%, 28.8%, 7.3%, and 54.2% during each year of 2004～2009, respectively, indicating its high prevalence in Korea throughout the years. PSaV induced with high prevalence (32.4-39.2%) during 2004～2005 but its detection rate was markedly decreased during 2006～2009. PToV caused sporadic infections only during 2006 (1.0%) and 2007 (6.9%). These enteric viruses were detected in diarrhea specimens in piglets usually in combination with each other and/or together with bacterial pathogens including the Escherichia coli, Salmonella spp., Brachispira hyodysenteriae, and Lawsonia intracellularis. Infections with PGARV, PGCRV, PSaV, and PToV were more prevalent in fecal samples collected in cold seasons. These results provide important epidemiological data for the control and establishment of a surveillance system for the prevailing enteric viruses in Korea.
Porcine circovirus type 2 (PCV2) is associated with porcine circovirus diseases (PCVD), of which postweaning multisystemic wasting syndrome is considered to cause considerable economic losses in pig industry worldwide. As the virus-like particle (VLP) is a highly effective type of subunit vaccine and has unique advantages in terms of safety and immunogenicity, this study aimed to develop PCV2-like particles, which matched currently circulating Korean PCV2 and were applicable as vaccines. The ORF2 genes encoding PCV2 capsid protein were amplified from the PCV2 subgroup 1A/B Korean C275 isolate and the subgroup 2E C94 isolate by PCR assay with primer pair specific to PCV2 ORF2 gene, and were cloned into baculovirus transfer vector. Recombinant baculovirus was generated by cotransfection with the transfer vector and linear baculovirus DNA into the Sf9 cells, and then by plaque purification. Expression of PCV2 capsid protein was determined by the indirect immunofluorescence and Western blotting assays, and electron microscopy. By both immunological assays, PCV2 capsid antigen was detected in the Sf9 cells infected with the recombinant baculoviruses. The formation of empty virus particles, characteristic of VLP, was detected in the lysate of Sf9 cells infected with the recombinant baculoviruses by negative electron microscopy. From these results, VLPs of two genogroups of PCV2 were successfully expressed and generated in a baculovirus expression system. It is expected that the expressed VLPs of two genotypic groups can be used for control of PCV2 infection as good vaccine candidates.
Aflatoxins produced by Aspergillus spp. are recognized as a major concern in animal and human health. In pigs, ingestion of aflatoxin-contaminated feeds causes immunosuppression, hepatotoxicosis and poor feed efficiency. In this study, we screened the contaminated level of aflatoxins in 449 pig feeds from 12 swine farms in Korea. For rapid and efficient screening of aflatoxins in pig feeds we evaluated the feasibility of three commercial ELISA kits for the screening of aflatoxins in pig feeds. Twenty-nine pig feed samples were examined for total aflatoxins using three ELISA kits, simultaneously. From three repetitions of each assay, the average intra-assay precisions and the average inter-assay precisions expressed as coefficient of variation (CV, %) for VeratoxⓇ Quantitative Aflatoxin test were 6.90 and 12.29, respectively. A statistical comparison of the results between HPLC and ELISAs showed that the correlation coefficient values for VeratoxⓇ was 0.96. The results demonstrated that we can apply the VeratoxⓇ Quantitative Aflatoxin test for the detection of aflatoxins in pig feed from the field. The screening of field samples with this ELISA kit showed that 11 out of 265 pig feeds for growers and weaners were contaminated with total aflatoxin levels exceeding 10 ppb, maximum tolerable limits for their compound feeds and the aflatoxins levels of remaining 184 pig feeds for other age groups of pigs were confirmed as below 20 ppb. The results from the screening indicated overall low levels of aflatoxins contamination in pig feeds.
A simple, selective and sensitive procedure for the confirmation of 14 sulfonamide antibacterials in milk was developed. The milk samples were homogenized, extracted and deproteinized by acetonitrile and defatted by n-hexane. Analysis was performed by liquid chromatography with tandem mass spectrometry (LC-MS/MS) in positive mode for all 14 analytes. Mass spectral acquisition was performed in the multi reaction monitoring mode (MRM), selecting two structurally significant transitions per compound. The calibrations were performed in sample matrixes and the interference effect of sample matrixes on the ionization was effectively eliminated. Good linear relationship (R2=0.992～ 0.999) were observed at 6 concentrations of 2.5～100 ng/g. Satisfied recoveries (86.3～110.2%) of all sulfonamides were demonstrated in spiked milk at three levels from 5 to 20 ng/g. The limits of quantitation (LOQs) for sulfonamides ranged from 0.25～2.1 ng/g.
For the screening of Brucella antibodies in pig, 2,140 pig serum samples were collected from six slaughter house in Korea between 2006 and 2007. The Rose Bengal test (RBT) and serum agglutination test (SAT) were used for initial screening for specific antibodies to Brucella, and competitive enzyme-linked immunosorbent assay (C-ELISA) was used for confirmation of presence of serum antibody for Brucella. Overall, 575 (26.9%) samples resulted in seropositive in RBT. In SAT, 50 (2.3%) and 10 (0.5%) samples showed suspicious positive and positive reaction, respectively, however, all sera tested in this study showed a negative reaction in C-ELISA. SAT and C-ELISA might be applicable as a tool for screening of swine brucellosis.
Toxocara (T.) canis, round worm of dogs and cats, is probably the most common gastrointestinal helminthes of domestic canid and is ascarid nematodes in the order Ascaridida, family Toxocaridae. The prevalence of patent toxocariasis is highest in the young dogs and much less common in adult dogs. There are few reports on the status of T. canis prevalence of dogs in Korea. Few cases of human visceral larva migrans also reported in Korea. However, as far as we know, there is no report on the canine toxocariasis case determined by pathological findings in Korea until now. In this research, we diagnosed canine toxocariasis by fecal egg test and pathologic findings in 2-month old two Pointer dogs. Typical T. canis eggs were detected in the fecal test. Numerous adult ascarids in the lumen of small intestine and stomach in one dog and multifocal white necrotic lesions in lung, liver, and kidney in another dog were observed grossly. Histologically, multifocal necrosis, eosinophilic inflammation and intralesional ascarid larva were prominent findings in the lung, liver and kidney.