Prefectural Institutes Research Articles

Analysis of Long-term Variations of Atmospheric Nitrogen Deposition in Japan: Based on the Researches by Prefectural Institutes

Analysis of Long-term Variations of Atmospheric Nitrogen Deposition in Japan: Based on the Researches by Prefectural Institutes

Epidemiological Aspects of Escherichia albertii Outbreaks in Japan and Genetic Characteristics of the Causative Pathogen.

Zoonotic pathogen Escherichia albertii has been identified as the cause of several human disease outbreaks; however, factors such as the general symptoms and incubation period of E. albertii infection have yet to be defined. Therefore, we aimed to determine the unique aspects of E. albertii outbreaks in Japan and to examine the genetic characteristics of the causative pathogen. We studied all known E. albertii outbreaks that occurred in Japan up until 2015, which consisted of five confirmed outbreaks and one putative outbreak (Outbreaks 1-6). Outbreaks were re-examined based on personal communications between researchers in prefectural and municipal public health institutes, and through examination of any published study conducted at the time. Draft genome sequences of outbreak-associated E. albertii isolates were also generated. The most common symptom displayed by patients across the six episodes was watery diarrhea (>80%), followed by abdominal pain (50-84%) and fever (37.0-39.5°C) (26-44%). The estimated average incubation period of E. albertii infection was 12-24 h. We assumed that most of the outbreaks were foodborne or waterborne, with restaurant foods, restaurant water, and boxed lunches being the suspected transmission vehicles. Three of the six outbreak-associated E. albertii isolates possessed intact ETT2 regions, while the remaining isolates contained disrupted ETT2-encoding genes. Virulence gene screening revealed that more than half (44/70) of the tested genes were present in all 5 strains examined, and that each of the strains contained more than 1 gene from 14 out of the 21 groups of virulence genes examined in this study. The five E. albertii strains were classified into four of the five known phylogroups. Therefore, we determined that multiple E. albertii genotypes in Japan have the potential to cause outbreaks of diarrhea, abdominal pain, and/or fever following infection of a human host.

Influence of Stx2 Subtype on Bacteriological Identification of Outbreaks of EHEC O157：H- Infections in Saitama City

In 2013, two outbreaks of enterohemorrhagic Escherichia coli (EHEC) occurred in Saitama city. According to reports from each of the medical institutions that detected the EHEC isolates, the isolates seemed to differ in their production of Vero Toxin (VT / Shiga Toxin: Stx) since one isolate produced only Stx1 and the other produced both Stx1 and Stx2. However, a patient survey conducted by a public health center revealed that common foodstuffs had been consumed in both outbreaks. Because, the two EHEC isolates were newly detected from two people in one patient's family, we analyzed the phenotypic and genetic relationships among four isolates in total. All the isolates were serotyped as O157: H-, and both stx1 and stx2 were detected. Subsequently, all four isolates were shown to have the same pulsed-field gel electrophoresis (PFGE) banding pattern. The findings suggested that these isolates belonged to the same strain group. Among these cases, the isolates had stx2c which is one of the stx2 subtypes. Reportedly, some cases with the Stx2 subtype can not be detected using conventional tests for toxin. In addition, Stx2 can be overlooked as a result of this limitation of Stx-production tests. Both epidemiological research by public health centers and genetic analysis by prefectural and municipal public health institutes (PHIs) are very important for clarifying possible relationships among outbreaks, as in the present cases. Moreover, collaborations and networks among medical institutions, PHIs and public health centers should be further strengthened to prevent the spread of infections.

Modeling low salinity waters along the coast around Japan using a high-resolution river discharge dataset

The effect of river runoff on the salinity distribution in the coastal regions of Japan is investigated with a nested-grid model system. High-resolution river runoff data calculated by a hydrological cycle model are used in this study. Freshwater fluxes from rivers result in extremely low salinity waters along the coast of Japan. Fixed line observations conducted by prefectural fisheries research institutes show that such low salinity waters also exist in the real ocean. The use of the river runoff data noted above leads to reduction in root mean square errors (RMSEs) of sea surface salinity between observational data and the model result. The model experiments also show that freshwater inputs from large rivers can affect the salinity distribution far away from their mouths, which suggests that we should care about such rivers far away from the area of interest as well as local rivers. The experiment with runoff from non-Class-A rivers shows the smaller RMSE than the experiment without river runoff. Such small rivers also contribute a lot to improving reproducibility of the salinity distribution in the coastal areas. These results clearly show that precise data for river discharge are essential for realistic coastal modeling.

Current status of bacteriological studies at prefectural and municipal public health institutes in Japan

Prefectural and municipal public health institutes are located in prefectures and ordinance-designated cities in Japan, and play a vital role in the regional surveillance of infectious diseases and foodborne illnesses. These institutes, in close cooperation with national institutes such as the National Institute of Infectious Diseases and the National Institute of Health Sciences, construct the national surveillance network for infectious diseases and their causative agents. Bacteriological examinations and studies on a variety of infectious diseases and foodborne illnesses are core activities of prefectural and municipal public health institutes, through which novel and important bacteriological findings have been acquired. In this article, we report the latest findings regarding bacteriological examinations/studies and interesting cases at these institutes, especially concerning foodborne illnesses, tuberculosis, and antimicrobial resistances.

Shiga Toxin (Verotoxin)-Producing Escherichia coli in Japan.

A series of outbreaks of infection with Shiga toxin (verocytotoxin)-producing Escherichia coli or enterohemorrhagic E. coli (EHEC) O157:H7 occurred in Japan in 1996, the largest outbreak occurring in primary schools in Sakai City, Osaka Prefecture, where more than 7,500 cases were reported. Although the reason for the sudden increase in the number of reports of EHEC isolates in 1996 is not known, the number of reports has grown to more than 3,000 cases per year since 1996, from an average of 105 reports each year during the previous 5-year period (1991-1995). Despite control measures instituted since 1996, including designating Shiga toxin-producing E. coli infection as a notifiable disease, and nationwide surveillance effectively monitoring the disease, the number of reports remains high, around 3,800 cases per year. Serogroup O157 predominates over other EHEC serogroups, but isolation frequency of non-O157 EHEC has gone up slightly over the past few years. Non-O157 EHEC has recently caused outbreaks where consumption of a raw beef dish was the source of the infection, and some fatal cases occurred. Laboratory surveillance comprised prefectural and municipal public health institutes, and the National Institute of Infectious Diseases has contributed to finding not only multiprefectural outbreaks but recognizing sporadic cases that could have been missed as an outbreak without the aid of molecular subtyping of EHEC isolates. This short overview presents recent information on the surveillance of EHEC infections in Japan.

Analysis and Identification of Illegal Constituents in Health Food Products Implicitly Advertizing Tonic or Slimming Effect in the National Institute of Health Sciences in Japan

With the prefectural governments' aid of the purchase, the Division of Pharmacognosy, Phytochemistry and Narcotics, National Institute of Health Sciences (NIHS) successively has surveyed illegal constituents in health food products implicitly advertizing tonic or slimming effect since the fiscal year of 2002 (slimming type) or 2003 (tonic type). The average numbers of the analyzed products per year are about 100 (slimming type) and 150 (tonic type), respectively. We also continuously distribute standards of authentic samples of several illegal components such as N-nitrosofenfluramine (NFF) and sildenafil (SIL) to prefectural institutes and the average gross number per year is about 140. In the case of slimming type, the fact that the products containing NFF were widely sold in Japanese markets in 2002 is well known. In addition, phenolphthalein, fenfluramine, sibtramine, desdimethylsibtramine, orlistat, mazindol, Rhubarb, Senna Leaf, etc. have been found as illegal constituents. In the tonic type products, we have identified more than 20 synthetic compounds relating to the erectile dysfunction (ED) treatment drugs, SIL, vardenafil and tadalafil (TDF). Since 2005, their synthetic intermediates and the patented but non-approved PDE5 inhibitors also have been found. It should be noted that TDF was found in the shells of capsule in 2009 and that mutaprodenafil was found as pro-drug type illegal component in 2010. In this report identification method of these illegal constituents is briefly described and then analytical trend in this decade is reviewed.

Isolation of Vaccine-Derived Measles Viruses from Children with Acute Respiratory Infection

The measles elimination project led by the World Health Organization (WHO) has been moving toward the target of eliminating measles in the WHO Western Pacific Region. In Japan, prefectural public health institutes play a key role for the laboratory diagnosis of measles virus (MV) infection, which is based on PCR, virus isolation, and genotyping. Microscopic examination of viral-sensitive cell lines during routine virus isolation from nasopharyngeal specimens has been used to detect the morphological changes typical for the growth of respiratory viruses. Here, we describe the unexpected isolation of vaccine-derived MVs from the two unrelated 1-year-old boys with acute respiratory infection. The nasopharyngeal specimens were obtained from one patient in February 2007 and from another in December 2012. Incidentally, the two children had received measles-rubella vaccination 9 or 11 days before the sampling. The isolates from two children induced morphological changes of the viral-sensitive cell lines, such as syncythia formation (cell fusion). We finally identified the isolates as vaccine-derived MVs by sequence analysis and immunological methods with anti-measles nucleoprotein antibodies. As no typical symptoms of MV infection were observed in either patient, the vaccine-derived MVs were isolated not as causative pathogens but by chance. In fact, there was no suspected case of secondary MV infection in either patient, thereby excluding the possibility that vaccine-derived MVs spread from human to human. Our experiences suggest the possibility of vaccine-derived MV isolation by cell cultures and the difficulty in identifying MVs in specimens from patients other than clinically suspected measles cases.

Evaluation of Pulsed-Field Gel Electrophoresis Analysis Performed at Selected Prefectural Institutes of Public Health for Use in PulseNet Japan

Evaluation of Pulsed-Field Gel Electrophoresis Analysis Performed at Selected Prefectural Institutes of Public Health for Use in PulseNet Japan

Symposium The Forefront of Studies on Koi Herpesvirus Disease

Koi herpesvirus disease (KHVD) is an emergent cyprinid herpesvirus disease causing mass mortalities in koi and common carp Cyprinus carpio worldwide since 1998. In Japan, KHVD broke out in Autumn 2003 and has caused mass mortalities in farmed fish as well as wild fish all over Japan. Establishment of control measures against KHVD is the urgent theme, and in order to address this issue many scientists belonging to universities, national and prefectural research institutes, and pharmaceutical companies have studied on KHVD and produced excellent results. Not only scientists but also fish farmers are eager to know the results. This context motivated the author to organize a symposium in Mie. The symposium focused on the up-to-date results of studies on KHVD: KHV genome analysis, methods to inactivate KHV in the environmental water, ways to coexist with KHV, development of a delivery system for oral vaccination using liposome, and successful oral vaccination with liposomes entrapping KHV antigens.

Epidemiological and bacteriological investigation of enterohemorrhagic Escherichia coli infection in the Chugoku-Shikoku area

We investigated the occurring tendency of enterohemorrhagic Escherichia coli (EHEC) infection in the prefectural and municipal public health institutes in the Chugoku-Shikoku area from 1996 to 1999, and the bacteriological characteristics of EHEC isolated from these cases. Consequently, epidemiological analysis of the EHEC infection in this district was performed. 22 outbreaks in the various facilities showed the tendency occurred in infants and aged groups, and the serotypes of EHEC isolated from these outbreaks were O26, O111 etc. as well as O157. In 4 cases, EHEC were isolated from specimens of buckwheat noodles, salad, sand box, and goat feces, and these were determined as the source of infection. In 898 sporadic cases, including familial infection, the EHEC isolates were classified into 24 serotypes, and the genotypes of EHEC O157:H7 isolates by pulsed-field gel electrophoresis (PFGE) also varied. Moreover, since many asymptomatic carriers were detected in the adult group with familial infection, the existence of healthy carriers is as important as the source of infection. The drug-resistance test of EHEC isolates showed that 24% of the 924 isolates were resistant to drugs.

Characterization of enterohemorrhagic Escherichia coli O26 and development of its isolation media

We studied 101 strains of Enterohemorrhagic Escherichia coli (EHEC) O26 isolated from diarrhea patients in six prefectural institutes of public health in Japan during June 1996 and December 1997 and tried to establish an isolation medium for EHEC O26. None of the 101 EHEC O26 strains fermented rhamnose; Whereas all of the other EHEC including O157 and non-EHEC (166 strains) fermented rhamnose except 1 strain of non-EHEC. All of the randomly selected EHEC O26 (14 strains of O26:H11.2 strains of O26:H-) showed a very high resistance to potassium tellurite (Minimal Inhibitory Concentration (MIC) > or = 50 micrograms/ml), whereas all of the randomly selected non-EHEC (26 strains) but 1 showed a high sensitivity (MIC < or = 6.25 micrograms/ml) to this compound. On the basis of these results, we developed a Rhamnose MacConkey (RMAC) medium in which lactose in the MacConkey medium was replaced by rhamnose, and Cefixime-Potassium Tellurite-RMAC (CT-RMAC) medium in which Cefixime (0.05mg/l) and Potassium Tellurite (25mg/l) was added to RMAC for the isolation of EHEC O26 strains. We then evaluated the specifcity of these selective media by growing a selected number of O26 (24 strains) and 9 selected strains of bacteria. All of the EHEC O26 strains generated rhamnose non-fermented colonies (white color) on both media. In contrast to the EHEC O26, the vast majority of E. coli strains (166/167 = 99.4%) other than EHEC O26 were theoretically assumed to generate red colonies on the RMAC medium because of their rhamnose fermenting character and most of them were assumed not to grow on CT-RMAC medium because of their sensitivity to potassium tellurite. These findings and results indicate that EHEC O26 can be easily distinguished from other strains of E. coli including O157. Although EHEC O26 strains showed somewhat poor growth on CT-RMAC medium compared with that on RMAC medium, these O26 showed almost the same degree of growth on CT-RMAC as they showed on DHL media. The results of the present study demonstrated that the use of RMAC and CT-MRAC media for the isolation of EHEC O26 is very reliable and efficient with RMAC having good sensitivity and CT-RMAC having a better specificity for the isolation of this strain of EHEC.

最近における食品流通技術研究とその展望 特に公立試験研究機関の活動を中心に（後）

最近における食品流通技術研究とその展望 特に公立試験研究機関の活動を中心に（後）

最近における食品流通技術研究とその展望 特に公立試験研究機関の活動を中心に

最近における食品流通技術研究とその展望 特に公立試験研究機関の活動を中心に

Astrovirus as a cause of gastroenteritis in Japan

We used an enzyme immunoassay (EIA) to screen for astrovirus in stool specimens from outbreaks and sporadic cases of gastroenteritis collected between 1982 and 1992 in six prefectural public health institutes in Japan. Three outbreaks of gastroenteritis involving schoolchildren and adults were confirmed to be attributable to astrovirus. Astrovirus was detected in 6 to 10% of the specimens from patients with sporadic gastroenteritis from whom no other bacterial or viral agent had been identified. Among the sporadic cases, astrovirus was most frequently detected in infants less than 1 year of age, and the incidence peaked in March and April. Using specimens from recent outbreaks, we found that the EIA was more sensitive than electron microscopy (EM) for the detection of astrovirus, and many EM-negative specimens were positive by EIA. However, some stool specimens previously found to have astrovirus-like particles by EM were negative by EIA, perhaps because of inadequate storage conditions, such as long-term storage and repeated freezings and thawings. Our results indicate that astrovirus is more commonly associated with childhood gastroenteritis than has been previously appreciated and suggest that further studies to examine the epidemiology and disease burden of this virus are needed.

Average daily intake of pesticides and polychlorinated biphenyls in total diet samples in Osaka, Japan.

Total diet studies (also referred to as Market Basket Programs) have been conducted by the US Food and Drug Administration (FDA) since 1964. In Japan, similar studies have been carried out since 1977 by the National Institute of Hygienic Sciences in combination with some Prefectural Institutes of Public Health. This study was done to obtain fundamental data concerning the safety of foods; (1) the chemical contaminants in the foods eaten in selected areas in Japan were analyzed and their content determined, and (2) the problems and trends in the intake of these chemical and the sources of unusual residues were identified. The authors carried out these studies seven times between the fiscal year 1977 and 1985 in Osaka Prefectural (relatively urbanized district in comparison with a rural area in Japan). Daily dietary intake of organic contaminants was obtained and the means of these were calculated from the data.

Group A streptococci isolated from patients with infectious diseases in the surveillance system of pathogenic microbes in Akita and their serotypes

Group A streptococci were isolated from 690 (22.1%) out of 3, 128 of patients with various infectious diseases including scarlet fever, streptococcal infectious disease, tonsillitis, pharyngitis, upper respiratory infectious disease, etc. in the surveillance system of pathogenic microbes in Akita during the period from April, 1976 to March, 1986. The highest positive rate of the isolation wa 71.6% from patients with scarlet fever and the lowest rate was 0.9% from patients with diarrhea. Of 690 strains of the streptococci isolated, 608 (88.1%) were typed to 14 serotypes; type T12 (40.1%), T4 (19/3%), T6 (7.7%), Ti (4.8%), T13 (3.2%), T3 (3.0%), T28 (2.6%), TB3264 (2.5%), T25 (2.0%), T22 (1.4%), T14 (1.0%), T5 (0.1%), T9 (0.1%) and T23 (0.1%). Types T2, T8, T11, T18 and TImp. 19 of the streptococci, however, were not detected.Although yearly changes were observed in serotype distributions of many types, the trend in recent years in these serotypes was summarized to next three points; namely, (1) types T12 and T4 were still predominant, (2) types T3 and T28 increased, and (3) types T1, T6 and T13 decreased. It was noticed especially that the streptococci of type 3 isolated hardly in Akita until 1982 began to increase from 1983.Serotype distributions of types T12, T13, T25, T28 and TB3264 isolated from scarlet fever and streptococcal infectious disease of group I differed significantly from those from other infectious diseases of group III, with the exception of eruptive infectious disease, respectively. When serotype distributions of the isolates in Akita were also compared with those from prefectural and municipal public health institutes and health centers in Japan, the distributions of types T4, T12, T14 and T25 in Akita and types T1, T11, T13, T18, T22, T28 and TB3264 in Japan were significantly higher than those in Japan or in Akita, respectively.