Tomoe Shimada

Human infections with avian influenza A(H7N9) virus in China: preliminary assessments of the age and sex distribution.

WPSAR Vol 4, No 2, 2013 | doi: 10.5365/wpsar.2013.4.2.005 www.wpro.who.int/wpsar 1 a Emerging Disease Surveillance and Response, Division of Health Security and Emergencies, World Health Organization Regional Offi ce for the Western Pacifi c, Manila, Philippines. b Emerging Disease Surveillance and Response, World Health Organization China Offi ce, Beijing, China. * Members of the World Health Organization Regional Offi ce for the Western Pacifi c Event Management Team: Nyka Alexander, Jang Hwan Bae, Joy Rivaca Caminade, Erica Dueger, Xavier Dufrenot, Norikazu Isoda, Frank Konings, Chin-Kei Lee, Ailan Li, Michelle McPherson, Satoko Otsu, Karl Schenkel and Huu Thuan Vo. Submitted: 13 April 2013; Published: 20 April 2013 doi: 10.5365/wpsar.2013.4.2.005 Since 31 March 2013, the Government of China has been notifying the World Health Organization (WHO) of human infections with the avian influenza A(H7N9) virus,1 as mandated by the International Health Regulations (2005).2 While human infections with other subgroups of H7 influenza viruses (e.g. H7N2, H7N3 and H7N7) have previously been reported,3 the current event in China is of historical significance as it is the first time that A(H7N9) viruses have been detected among humans and the first time that a low pathogenic avian influenza virus is being associated with human fatalities.4 In this rapidly evolving situation, detailed epidemiologic and clinical data from reported cases are limited—making assessments challenging— however, some key questions have arisen from the available data. Age and sex data, as one of the first and Human infections with avian infl uenza A(H7N9) virus in China: preliminary assessments of the age and sex distribution

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.

Incidence of dengue virus infection among Japanese travellers, 2006 to 2010

INTRODUCTION Dengue continues to be a global public health concern. In Japan, although dengue cases are currently seen only among travellers returning from endemic areas, the number of reported cases is rising according to the national case-based surveillance system. We evaluated the characteristics of dengue cases imported into Japan and the relationship between the incidence of infection and season of travel to popular destinations. METHODS Dengue cases reported to the national surveillance system were retrospectively examined. The number of reported cases per number of Japanese travellers to a dengue-endemic country was calculated to estimate the country-specific incidence of imported dengue virus infection. The incidence of dengue infection among Japanese travellers was compared between dengue high season and low season in each country using relative risk (RR) and associated 95% confidence intervals (CI). RESULTS Among 540 Japanese residents who were reported as dengue cases from 2006 to 2010, the majority had travelled to Indonesia, India, the Philippines and Thailand. The RR of dengue infection among Japanese travellers during dengue high season versus low season was 4.92 (95% CI: 3.01-8.04) for the Philippines, 2.76 (95% CI: 1.67-4.54) for Thailand and 0.37 (95% CI: 0.15-0.92) for Indonesia. DISCUSSION Overall, higher incidence of imported cases appeared to be related to historic dengue high seasons. Travellers planning to visit dengue-endemic countries should be aware of historic dengue seasonality and the current dengue situation.

Epidemiological and Clinical Features of Severe Fever with Thrombocytopenia Syndrome in Japan, 2013-2014.

Although severe fever with thrombocytopenia syndrome (SFTS) was first reported from Japan in 2013, the precise clinical features and the risk factors for SFTS have not been fully investigated in Japan. Ninety-six cases of severe fever with thrombocytopenia syndrome (SFTS) were notified through the national surveillance system between April 2013 and September 2014 in Japan. All cases were from western Japan, and 82 cases (85%) had an onset between April and August. A retrospective observational study of the notified SFTS cases was conducted to identify the clinical features and laboratory findings during the same period. Of 96 notified cases, 49 (51%) were included in this study. Most case-patients were of advanced age (median age 78 years) and were retired or unemployed, or farmers. These case-patients had a history of outdoor activity within 2 weeks before the onset of illness. The median serum C-reactive protein concentration was slightly elevated at admission. Fungal infections such as invasive aspergilosis were found in 10% of these case-patients. Hemophagocytosis was observed in 15 of the 18 case-patients (83%) whose bone marrow samples were available. Fifteen cases were fatal, giving a case-fatality proportion of 31%. The proportion of neurological abnormalities and serum concentrations of lactate dehydrogenase and aspartate aminotransferase were significantly higher in the fatal cases than in the nonfatal cases during hospitalization. Appearance of neurological abnormality may be useful for predicting the prognosis in SFTS patients.

Epidemiological and genetic analyses of a diffuse outbreak of hepatitis A in Japan, 2010.

BACKGROUND Hepatitis A virus (HAV) is still one of the most common causative agents of acute hepatitis in Japan. Although a relatively small number of annual acute hepatitis A cases (approximately 100-150, 0.78-1.17 per million) were recently reported, a larger number of cases (346, 2.71 per million) were reported in 2010. OBJECTIVES To investigate the causes of the 2010 HAV resurgence in Japan by using molecular epidemiological and genetic analyses. STUDY DESIGN HAV specimens were obtained from 61 cases from 22 different prefectures. These viral specimens were genotyped by PCR amplification and sequencing of the VP1/2A region of HAV genome. RESULTS Phylogenetic analysis revealed that 61 HAV strains could be divided into three genotypes: IA (44 cases), IB (1 case) and IIIA (16 cases). The IA genotype consisted of two genomic sub-lineages. The sequences of one of the two IA sub-lineages (corresponding to 31 cases) were very similar, 26 of these 31 isolates had 100% identity. The other IA sub-lineage corresponded to strains endemic to Japan. The sequences of Japanese IIIA strains were similar to those of strains that caused a large epidemic in the Republic of Korea from 2007 to 2009. CONCLUSIONS The resurgence of HAV in 2010 can be attributed to importation of two newly emerged HAV genotypes.

Ongoing local transmission of dengue in Japan, August to September 2014.

WPSAR Vol 5, No 4, 2014 | doi: 10.5365/wpsar.2014.5.3.007 www.wpro.who.int/wpsar 1 a Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan. b Department of Virology, National Institute of Infectious Diseases, Tokyo, Japan. c Department of Medical Entomology, National Institute of Infectious Diseases, Tokyo, Japan. Submitted: 26 September 2014; Published: 28 October 2014 doi: 10.5365/wpsar.2014.5.3.007 In late August 2014, three autochthonous dengue cases were reported in Japan. Since then, as of 17 September 2014, a total of 131 autochthonous cases have been confirmed. While cases were reported from throughout Japan, the majority were linked to visiting a large park or its vicinity in Tokyo, and the serotype detected has been serotype 1. We report preliminary findings, along with the public health response activities, of the first documented autochthonous dengue outbreak in Japan in nearly 70 years.

Dengue Sentinel Traveler Surveillance: Monthly and Yearly Notification Trends among Japanese Travelers, 2006–2014

Background Dengue is becoming an increasing threat to non-endemic countries. In Japan, the reported number of imported cases has been rising, and the first domestic dengue outbreak in nearly 70 years was confirmed in 2014, highlighting the need for greater situational awareness and better-informed risk assessment. Methods Using national disease surveillance data and publically available traveler statistics, we compared monthly and yearly trends in the destination country-specific dengue notification rate per 100,000 Japanese travelers with those of domestic dengue cases in the respective country visited during 2006–2014. Comparisons were made for countries accounting for the majority of importations; yearly comparisons were restricted to countries where respective national surveillance data were publicly available. Results There were 1007 imported Japanese dengue cases (Bali, Indonesia (n = 202), the Philippines (n = 230), Thailand (n = 160), and India (n = 152)). Consistent with historic local dengue seasonality, monthly notification rate among travelers peaked in August in Thailand, September in the Philippines, and in Bali during April with a smaller peak in August. While the number of travelers to Bali was greatest in August, the notification rate was highest in April. Annually, trends in the notification rate among travelers to the Philippines and Thailand also closely reflected local notification trends. Conclusion Travelers to dengue-endemic countries appear to serve as reliable “sentinels”, with the trends in estimated risk of dengue infection among Japanese travelers closely reflecting local dengue trends, both seasonally and annually. Sentinel traveler surveillance can contribute to evidence-based pretravel advice, and help inform risk assessments and decision-making for importation and potentially for subsequent secondary transmission. As our approach takes advantage of traveler data that are readily available as a proxy denominator, sentinel traveler surveillance can be a practical surveillance tool that other countries could consider for implementation.

Exposure to H1 genotype measles virus at an international airport in Japan on 31 July 2016 results in a measles outbreak

a Field Epidemiology Training Program, National Institute of Infectious Diseases. b Department of Epidemiology for Infectious Diseases, Graduate School of Medicine, Osaka University, Japan. c Infectious Disease Surveillance Center, National Institute of Infectious Diseases. d Department of Virology III, National Institute of Infectious Diseases. e Division of Global Infectious Diseases, Department of Infection and Epidemiology, Graduate School of Medicine, Tohoku University, Miyagi, Japan. Submitted: 22 December 2016; Published: 07 February 2017 doi: 10.5365/wpsar.2016.7.4.007 Exposure to H1 genotype measles virus at an international airport in Japan on 31 July 2016 results in a measles outbreak

Increase in paratyphoid fever cases in Japanese travellers returning from Cambodia in 2013

In 2013, an unusual increase of paratyphoid fever cases in travellers returning from Cambodia was reported in Japan. From December 2012 to September 2013, 18 cases of Salmonella Paratyphi A infection were identified. Microbiological analyses revealed that most isolates had the same clonal identity, although the epidemiological link between these cases remains unclear. It was inferred that the outbreak was caused by a common and persistent source in Cambodia that was likely to have continued during 2014. The information of surveillance and laboratory data from cases arising in travellers from countries with limited surveillance systems should be timely shared with the country of origin.

Epidemiological situation of Ebola virus disease in West Africa.

After Guinea reported an outbreak of Ebola virus disease (EVD) in March 2014, EVD spread to neighboring Sierra Leone and Liberia in West Africa. Since then, the EVD outbreak spread over a wide geographic area among these three countries, and became the largest EVD epidemic ever with unprecedented numbers of confirmed cases and fatalities. As of April 2015, one year past the start of the outbreak, transmission is still ongoing. And, while six other countries, including those outside of the African continent (the United Kingdom, Spain, and the United States), have reported EVD cases, the source of the infection all originated from Guinea, Sierra Leone, or Liberia. As for the pathogen, Ebola virus, the route of transmission and associated prevention measures are well known, and change in the virulence or transmissibility of the virus has not been confirmed. However, there are specific factors that likely contributed to the unprecedented magnitude of the current EVD outbreak. In addition to the limited and poor medical and public health infrastructure in the affected countries, implementing appropriate responses rapidly was challenging for these countries, whose medical community, the general public, and governments had never experienced EVD before.