Pandemic (H1N1) 2009 transmission during presymptomatic phase, Japan.

During an epidemiologic investigation of pandemic influenza (H1N1) 2009 virus infection in May 2009 in Osaka, Japan, we found 3 clusters in which virus transmission occurred during the presymptomatic phase. This finding has public health implications because it indicates that viral transmission in communities cannot be prevented solely by isolating symptomatic case-patients.

[Epidemiology of acute encephalitis or encephalopathy in Japan].

Epidemiological situation on acute encephalitis in Japan from 2004 to 2009 are described. Acute encephalopathy suspected infectious disease origin such as influenza encephalopathy are involved. Data are based on the National Epidemiological Surveillance of Infectious Diseases (NESID) under Infectious Disease Control Law. During these 6 years, 1467 cases are reported. More than 50% of them are less than 10 year old, and top age group is 1 yo and the second group is 0 yo. In 2004, acute encephalopathy outbreak(cause unknown although mushroom poisoning was suspected) occurred in northern part of Japan, and this event was detected under this reporting system. Major cause of acute encephalitis/encephalopathy are influenza virus infection (acute influenza encephalopathy: AIE) and many AIE cases were reported during influenza A/H1N1 2009 outbreak. Eight cases of measles encephalitis among adolescence and young adult age were reported in 2007, however, no report since 2008.

Genomic characterization of clinical Enterobacter roggenkampii co-harbouring blaIMP-1- and blaGES-5-encoding IncP6 and mcr-9-encoding IncHI2 plasmids isolated in Japan.

OBJECTIVES: The spread of carbapenemase-producing Enterobacterales (CPE) with colistin resistance is a critical public health issue. We genetically characterized the clinical isolate Enterobacter roggenkampii OIPH-N260, which harboured carbapenemase genes blaIMP-1 and blaGES-5 with multiple resistance genes, including mcr-9 and blaCTX-M-9. METHODS: This isolate was characterized by whole-genome sequencing, comparative analysis of resistance plasmids, susceptibility tests, bacterial conjugation, S1-nuclease digested pulsed-field-gel electrophoresis, and Southern blot hybridization. RESULTS: The OIPH-N260 isolate exhibited resistance to most ß-lactams and colistin. It co-harboured two resistance plasmids, the blaIMP-1- and blaGES-5-encoding IncP6 plasmid pN260-3 and mcr-9- and blaCTX-M-9-encoding IncHI2 plasmid pN260-1. The comparative analysis of pN260-3 indicated that a unique blaIMP-1-surrounding region was inserted into the blaGES-5-encoding plasmid with the mobile element IS26, which plays an important role in the spread of resistance genes. pN260-1 did not possess the mcr-9 expression regulative gene qseBC. Both plasmids were transferable into other bacterial species via conjugation. CONCLUSIONS: This is the first study to report not only a blaIMP-1 and blaGES-5 co-encoding plasmid, but also the co-harbouring of another plasmid carrying mcr-9 and blaCTX-M-9 in Enterobacter cloacae complex. The development of advanced resistance via IS26-mediated insertion and the co-harbouring of resistance plasmids highlights the need to monitor for resistance genes in CPE.

[Tsutsugamushi disease and Japanese spotted fever recognition among medical seminar participants for the general public in epidemic and non-epidemic areas].

Questionnaires on Tsutsugamushi disease (TD) and Japanese spotted fever (JSF) recognition, were distributed at lectures to the general public held in Sakai, Osaka (Lecture A), and Sumoto, Hyogo (Lecture B). Questions included knowledge of transmission routes, symptoms, and seeing physicians after having suspected symptoms. Hyogo had more reported cases of both diseases than Osaka. The response was 57.9% (113/195) to Lecture A, and 87.2% (61/70) to Lecture B. Analysis covered 89 Lecture A and 53 Lecture B respondents after excluding medical and public health specialists and those with unknown occupations. Disease recognition for JSF, knowledge of TD transmission routes, and symptoms of both diseases were better among Lecture B respondents -a statistically significant finding. The two groups saw physicians after having suspected symptoms at roughly the same rate. When these two groups were combined, those with knowledge of transmission routes or symptoms were significantly more likely to see physicians (p<0.05).

Immune thrombocytopenic purpura risk by live, inactivated and simultaneous vaccinations among Japanese adults, children and infants: a matched case-control study.

This case-control study investigated immune thrombocytopenic purpura (ITP) risk following live, inactivated, and simultaneous vaccination, with a focus on infants aged < 2 years. We matched case patients with ITP to one or two control patients with other diseases by institution, hospital visit timing, sex, and age. We calculated McNemar's pairwise odds ratios (ORs [95% confidence interval]) with 114 case-control pairs. The case group had 27 (44%) males and 22 (35%) infants, and the control group included 49 (43%) males and 42 (37%) infants. For all age groups, the McNemar's OR for ITP occurrence was 1.80 (0.54-6.84, p = 0.64) for all vaccines. Among infants, these were 1.50 (0.17-18.0, p = 0.50) for all vaccines, 2.00 (0.29-22.1, p = 0.67) for live vaccines, and 1.00 (0.01-78.5, p = 0.50) for inactivated vaccines. Sex-adjusted common ORs for simultaneous vaccination were 1.52 (0.45-5.21, p = 0.71) for all vaccines, 1.83 (0.44-7.59, p = 0.40) for inactivated vaccines only, and 1.36 (0.29-6.30, p = 0.69) for mixed live and inactivated vaccines. In infants, these were 1.95 (0.44-8.72, p = 0.38), 1.41 (0.29-6.94, p = 0.67) and 2.85 (0.43-18.9, p = 0.28), respectively. These limited data suggest no significant ITP risk following vaccinations or simultaneous vaccination in any age group, including infants.

Serological survey of avian H5N2-subtype influenza virus infections in human populations.

To investigate the distribution of antibodies against H5N2 influenza virus in humans living in Ibaraki prefecture, Japan, 266 single serum samples were collected to perform serological tests. Results were compared to investigate the relationship between positive results and several factors. The number of positive serum neutralization antibody titers (> or = 40) against avian influenza virus A/H5N2 was significantly greater (P < 0.05) among poultry workers, in comparison to a Japanese healthy population. The geometric mean titers of serum neutralization antibody against A/H5N2 were significantly higher (P < 0.05) among Ibaraki inhabitants and poultry workers (P < 0.0001) when compared to a Japanese healthy population. Seropositivity against A/H5N2 virus was significantly (P < 0.05) associated with age (> or = 50 years old) in poultry workers. These results suggest that seropositivity against H5N2 virus in Ibaraki specimens is significantly higher than those of a Japanese healthy population and that the surveillance of avian influenza viruses is very important to evaluate the invasion or emergence of new pandemic influenza viruses from species other than humans.

Seasonal influenza surveillance using prescription data for anti-influenza medications.

Surveillance is critical for both early detection and a timely public health response to infectious diseases. Electronic information systems have been widely adopted by pharmacies in Japan. The aim of this study is to evaluate the feasibility of using prescription data for influenza surveillance in Japan to facilitate the development of a daily reporting system. This is a retrospective study using questionnaires mailed to pharmacies in Sakai City, Osaka, Japan in October 2007. The total number of prescriptions for oseltamivir and zanamivir and the number of influenza cases reported by sentinel surveillance in Sakai during the investigation period showed excellent correlation, with a correlation coefficient of 0.954. Further analysis showed that the data from as few as eight pharmacies result in a correlation coefficient of 0.9. These results demonstrate the feasibility of such a system and that pharmacy prescription data are a very useful indicator of sentinel surveillance for influenza.

Diarrhea as a minor adverse effect due to oral polio vaccine.

Using the adverse events monitoring system of Japan, we observed diarrhea cases in approximately 10% of patients who received oral poliovirus vaccine (OPV). This study was conducted to investigate whether diarrhea among children aged 0 to 1 is caused by OPV or by other factors such contact at the doctor's office and/or with others outside the home. We conducted a survey of the health of children after regular health check-ups and after the administration of the OPV. The data from the health check-ups were used as a control for the OPV case group. We compared the first-OPV dose vaccination group as well as the second-OPV dose vaccination group to the health check-up group. For cases of diarrhea, the odds ratio of the OPV group to the health check-up group was 1.776. Our findings strongly suggest that post-OPV cases of mild diarrhea are closely related to the administration of the OPV.

[2008 G8 Hokkaido Toyako Summit Meeting Syndrome Surveillance].

We conducted syndromic surveillance for the Hokkaido, Japan, Toyako Group of Eight (G8) summit meeting in July 2008 as a counter-measure to bioterrorism attacks and other health emergencies. Surveys were conducted from June 23, two weeks before the summit, to July 23 two weeks after it, with part of those for prescription drugs fully automated, and part by manual input over the World-Wide-Web. Those for ambulance transfer were done similarly. We bought over-the-counter (OTC) sales data from two private research firms in Japan and had the monitor, who had contacts with a private research company, report health conditions via personal computer (PC) or cellphone. We had a virtual conference daily at 9:00 with the local Hokkaido government, local public health center, local Hokkaido public laboratory, the National Institute of Infectious Diseases, and the Ministry of Health, Labor and Welfare to decide whether local public health centers would be required to investigate. Fully automated syndromic surveillance was conducted by 23 pharmacies for prescriptions drugs, and 71 pharmacies provided manual corporate input. One fire department covering Toyako and a VIP support team used fully automated syndromic surveillance and seven Toyako fire departments used manual input. For 79 pharmacies providing OTC sales data, data provision was delayed one day and analysis could not be automated. Four hundred and seventy two households corporate web search for their health conditions. It also automatically analyzed and feed backed. No notable outbreak occurred during the summit, but public health centers investigated seven aberration detected by syndrome surveillance for ambulance transfer. Although a fully automated system was concidered best for early outbreak detection manual input and analysis were also required. Routine, fully automatied syndromic surveillance remains to be realized in Japan.

Human H5N2 avian influenza infection in Japan and the factors associated with high H5N2-neutralizing antibody titer.

BACKGROUND: H5N2 avian influenza virus infection of humans has not been reported thus far. The first H5N2 avian influenza infection of poultry in Japan occurred in Ibaraki. METHODS: The subjects were workers at 35 chicken farms in Ibaraki Prefecture, where the H5N2 virus or antibody was isolated from chickens. None of the subjects exhibited influenza symptoms. The H5N2-neutralizing antibody titers of the first and second paired sera samples were compared. To investigate the possible factors for this increase, the H5N2-neutralizing antibody titer (1:40 or more) was calculated for the second samples. A logistic regression analysis was performed to examine the association of these factors with H5N2-neutralizing antibody positivity. RESULTS: We performed Wilcoxon matched-pairs signed-ranked test on data collected from 257 subjects, and determined that the H5N2 antibody titers of the second paired sera samples were significantly higher than those of the first samples (P < 0.001). The H5N2 antibody titers of paired sera of 13 subjects without a history of seasonal influenza vaccination within the previous 12 months increased 4-fold or more. The percentage of antibody positivity was 32% for subjects with a history of seasonal influenza vaccination (28% of all subjects) and 13% for those without a history of the same. The adjusted odds ratio of H5N2-neutralizing antibody positivity was 4.6 (95% confidence interval: 1.6-13.7) for those aged over 40 and 3.1 (95% confidence interval: 1.6-6.1) for those with a history of seasonal influenza vaccination within the previous 12 months. CONCLUSION: The results suggest that this may have been the first avian influenza H5N2 infection of poultry to affect humans. A history of seasonal influenza vaccination might be associated with H5N2-neutralizing antibody positivity.

Sequence and phylogenetic analysis of the nucleoprotein (N) gene in measles viruses prevalent in Gunma, Japan, in 2007.

In 2007, relatively large outbreaks of measles occurred in the Kanto region of Japan, including Gunma Prefecture. We performed sequence and phylogenetic analysis of the nucleoprotein gene (N gene) of measles viruses from 3 measles patients in this area in May 2007. The N gene sequences of the present strains were identical to each other, and phylogenetic analysis showed these viruses were classified into genotype D5. The results suggest that highly homologous measles viruses may be associated with outbreaks of measles in Gunma, Japan.

[Seasonal influenza activity in Japan and epidemiological investigation for avian influenza].

We analyzed the seasonal influenza activity in 2004/05 and 2005/06 seasons. In 2004/05 season, the prevalence of influenza started lately. The arrival of a peak of influenzal prevalence was the ninth week, and was late in comparison with an average year. The prevalence scale was very large, and the estimation number of patients was 17,700,000. Since the start of the 2004/05 season, influenza activity has mainly been associated with influenza B viruses. The start of prevalence of 2005/06 season was 50th week and was comparatively early. The peak of the prevalence was the 4th week, same as an average year. Since the start of the 2005/06 season, influenza activity has mainly been associated with influenza A/H3 viruses.H5N1 highly pathogenic avian influenza virus have spread through Africa and Europe from Asia. For purpose such as inhibition of the outbreak of new variant influenza, the prevention of human to human infection and expansion, early containment, the public health organization has to do unified epidemiological investigation immediately nationwide. By doing epidemiological investigation, the prevention of infection expansion, specification of the source of infection, assessment of the risk of infection, and early detection of new variant influenza virus and containment, are expected.

Description of hospitalized cases of influenza A(H1N1)pdm09 infection on the basis of the national hospitalized-case surveillance, 2009-2010, Japan.

This study reports the epidemiological characteristics of hospitalized cases of influenza A(H1N1)pdm09 infection analyzed on the basis of surveillance data collected from July 24, 2009, the date on which the hospital-based surveillance of influenza cases was implemented in Japan, to September 5, 2010. During the study period, 13,581 confirmed cases were reported. Among those cases with information regarding the reason for hospitalization, 39% were admitted to hospitals for non-therapeutic purposes such as medical observation and laboratory testing. The overall hospitalization rate was 5.8 cases per 100,000 population when cases hospitalized for non-therapeutic purposes were excluded. While those aged under 20 years accounted for over 85% of hospitalized cases, the largest proportion of fatal cases was observed in those aged over 65 years. The overall case fatality rate for all hospitalized cases was 1.5%. The year-round surveillance for hospitalized influenza-like illness cases was launched in 2011, and it was expected that this surveillance system could add value by monitoring changes in the epidemiological characteristics of hospitalized cases of seasonal influenza.

Nosocomial Serratia marcescens outbreak in Osaka, Japan, from 1999 to 2000.

OBJECTIVES: To investigate and control an outbreak of bloodstream infections (BSIs) caused by Serratia marcescens and to identify risk factors for respiratory colonization or infection with S. marcescens. DESIGN: Epidemiologic investigation, including review of medical and laboratory records, procedural investigations, pulsed-field gel electrophoresis (PFGE) typing of environmental and patient isolates, statistical study, and recommendation of control measures. PATIENTS AND SETTING: All patients admitted to a 380-bed, secondary-care hospital in Osaka Prefecture, Japan, from July 1999 through June 2000 (study period). RESULTS: Seventy-one patients were colonized or infected with S. marcescens; 3 patients who developed primary BSIs on the same ward within 5 days in June 2000 had isolates with indistinguishable PFGE patterns and indwelling intravenous catheters for more than 5 days. On multivariate analysis, among 36 case-patients with positive sputum specimens and 95 control-patients, being bedridden (odds ratio [OR], 15.91; 95% confidence interval [CI95], 4.17-60.77), receiving mechanical ventilation (OR, 7.86; CI95, 2.27-27.16), being older than 80 years (OR, 3.12; CI95, 1.05-9.27), and receiving oral cleaning care (OR, 3.10; CI95, 1-9.58) were significant risk factors. S. marcescens was isolated from the fluid tanks of three nebulizers and a liquid soap dispenser. The hospital did not have written infection control standards, and many infection control practices were found to be inadequate (eg, respiratory equipment was used without disinfection between patients). CONCLUSIONS: Poor hospital hygiene and the lack of standard infection control measures contributed to infections hospital-wide. Recommendations to the hospital included adoption of written infection control policies.

National surveillance of influenza-associated encephalopathy in Japan over six years, before and during the 2009-2010 influenza pandemic.

Influenza-associated encephalopathy (IAE) is a serious complication of influenza and is reported most frequently in Japan. This paper presents an assessment of the epidemiological characteristics of influenza A (H1N1) 2009-associated encephalopathy in comparison to seasonal IAE, based on Japanese national surveillance data of influenza-like illness (ILI) and IAE during flu seasons from 2004-2005 through 2009-2010. In each season before the pandemic, 34-55 IAE cases (mean 47.8; 95% confidence interval: 36.1-59.4) were reported, and these cases increased drastically to 331 during the 2009 pandemic (6.9-fold the previous seasons). Of the 331 IAE cases, 322 cases were reported as influenza A (H1N1) 2009-associated encephalopathy. The peaks of IAE were consistent with the peaks of the influenza epidemics and pandemics. A total of 570 cases of IAE (seasonal A, 170; seasonal B, 50; influenza A (H1N1) 2009, 322; unknown, 28) were reported over six seasons. The case fatality rate (CFR) ranged from 4.8 to 18.2% before the pandemic seasons and 3.6% in the 2009 pandemic season. The CFR of pandemic-IAE was 3.7%, which is lower than that of influenza A-/B-associated encephalopathy (12.9%, p<0.001; 14.0%, p = 0.002; respectively). The median age of IAE was 7 years during the pandemic, which is higher than that of influenza A-/B-associated encephalopathy (4, p<0.001; 4.5, p = 0.006; respectively). However, the number of pandemic-IAE cases per estimated ILI outpatients peaked in the 0-4-year age group and data both before and during the pandemic season showed a U-shape pattern. This suggests that the high incidence of influenza infection in the 0-4 year age group may lead to a high incidence of IAE in the same age group in a future influenza season. Further studies should include epidemiologic case definitions and clinical details of IAE to gain a more accurate understanding of the epidemiologic status of IAE.

Geographic trends and spread of the pandemic (H1N1) 2009 in the metropolitan areas of Japan studied from the national sentinel data.

The identification of geographic trends of an influenza pandemic is important for analyzing its social epidemic factors. We performed spatiotemporal analyses focusing on the metropolitan areas in Japan by using the influenza-like illness (ILI) sentinel surveillance data for the pandemic (H1N1) 2009 and seasonal influenza. The epidemic curves and spread features expressed by the kriging method of geographic information system (GIS) and correlations between reported cases and demographic data were analyzed. The incidence of pandemic (H1N1) 2009 increased gradually at the beginning and showed more sporadic epidemic features compared to seasonal influenza. However, there were coincidental locations of patient clusters affected by the seasonal influenza, with a significant coefficient for the total sentinel reported cases (r = 0.71, P < 0.01). This suggested similar patterns of the epidemic over seasons. Patient clusters tended to be located in suburban areas, and there seemed to be stronger relationships between epidemics and higher ratio of larger families (with r = 0.26-0.35, P < 0.01, between ratio of families having more than 3 members and total reported cases in Tokyo and Nagoya areas). Whether populous areas had a greater probability of maintaining the epidemic patterns needs to be determined. Nonetheless, the patterns found in this study can be useful for further analyses for epidemic modeling and designing relevant controls.

Sex- and age-related differences in morbidity rates of 2009 pandemic influenza A H1N1 virus of swine origin in Japan.

BACKGROUND: The objective of the present study was to determine whether the morbidity rates of the 2009 pandemic influenza A H1N1 virus (pdmH1N1) varied by age and/or sex. METHODS AND FINDINGS: Retrospective analysis of 2,024,367 cases of pdmH1N1 was performed using the national surveillance data from influenza sentinel points in Japan. The male-to-female morbidity ratios (M/F ratios) in nineteen age groups were estimated as the primary outcome. The M/F ratios for pdmH1N1 influenza were: >1 in age groups <20 years and ≥80 years (p<0.001); <1 in age groups 20-79 years (p<0.001). This data suggests that males <20 years of age may be more likely to suffer from pdmH1N1 influenza than females in the same age categories. When the infection pattern for pdmH1N1 was compared with that of seasonal influenza outbreaks between 2000 and 2008, the M/F ratio for pdmH1N1 influenza was higher in ages 3-29 years and lower in ages 40-79 years. Because the present study was based on the national surveillance, it was impossible to estimate the morbidity rate for the Japanese population. It is also likely that the data did not capture asymptomatic or mild infections. CONCLUSIONS: Although exposure to the pdmH1N1 virus is assumed to be similar in both boys and girls, M/F ratios were >1 in those younger than 20 years. The subsequent reversal of the M/F ratio in the adult generation could be due to several possibilities, including: greater immunity among adult males, more asymptomatic infections among males, less reporting of illness by males, or differences in exposure to the virus and probability of visiting a clinic. These results suggest that the infection and virulence patterns of pdmH1N1 are more complex than previously considered.

Molecular evolutionary analysis of the influenza A(H1N1)pdm, May-September, 2009: temporal and spatial spreading profile of the viruses in Japan.

BACKGROUND: In March 2009, pandemic influenza A(H1N1) (A(H1N1)pdm) emerged in Mexico and the United States. In Japan, since the first outbreak of A(H1N1)pdm in Osaka and Hyogo Prefectures occurred in the middle of May 2009, the virus had spread over 16 of 47 prefectures as of June 4, 2009. METHODS/PRINCIPAL FINDINGS: We analyzed all-segment concatenated genome sequences of 75 isolates of A(H1N1)pdm viruses in Japan, and compared them with 163 full-genome sequences in the world. Two analyzing methods, distance-based and Bayesian coalescent MCMC inferences were adopted to elucidate an evolutionary relationship of the viruses in the world and Japan. Regardless of the method, the viruses in the world were classified into four distinct clusters with a few exceptions. Cluster 1 was originated earlier than cluster 2, while cluster 2 was more widely spread around the world. The other two clusters (clusters 1.2 and 1.3) were suggested to be distinct reassortants with different types of segment assortments. The viruses in Japan seemed to be a multiple origin, which were derived from approximately 28 transported cases. Twelve cases were associated with monophyletic groups consisting of Japanese viruses, which were referred to as micro-clade. While most of the micro-clades belonged to the cluster 2, the clade of the first cases of infection in Japan originated from cluster 1.2. Micro-clades of Osaka/Kobe and the Fukuoka cases, both of which were school-wide outbreaks, were eradicated. Time of most recent common ancestor (tMRCA) for each micro-clade demonstrated that some distinct viruses were transmitted in Japan between late May and early June, 2009, and appeared to spread nation-wide throughout summer. CONCLUSIONS: Our results suggest that many viruses were transmitted from abroad in late May 2009 irrespective of preventive actions against the pandemic influenza, and that the influenza A(H1N1)pdm had become a pandemic stage in June 2009 in Japan.