Takuri Takahashi

Epidemiological Characteristics of Rubella and Congenital Rubella Syndrome in the 2012–2013 Epidemics in Tokyo, Japan

A large rubella outbreak has been observed since June 2012 in Tokyo, Japan, and a rapid increase in the number of congenital rubella syndrome (CRS) cases have also been reported in Japan since October 2012. All the clinically diagnosed and laboratory-confirmed rubella cases reported in Tokyo from January 2012 to December 2013 and all the laboratory-confirmed CRS cases from January 2012 to March 2014 were analyzed. In total, 4,116 rubella cases were reported in Tokyo. Of these, 77.2% (n=3,176) were male; the highest number of cases occurred in males aged 35-39 years and in females aged 20-24 years. Complications included arthralgia/arthritis (19.4%), thrombocytopenic purpura (0.5%), hepatic dysfunction (0.3%), and encephalitis (0.1%). The circulating rubella virus in Tokyo was genotype 2B. The most possible site of transmission was the workplace. Because of the rubella epidemic, 16 CRS cases were reported in Tokyo from March 2013 to February 2014. Domestic infection with rubella was proven for all mothers of 16 cases. This situation suggests that Japan is still working to achieve rubella elimination.

Epidemiological and genetic analysis of a 2014 outbreak of hepatitis A in Japan.

Hepatitis A virus (HAV) is one of the most common causes of feces-transmitted acute hepatitis worldwide. In Japan, most of HAV infections have been sporadic cases and a relatively low number of cases (approximately 100-150) of acute hepatitis A were reported in 2012 and 2013. However, in 2014, 342 cases were reported as of week 22. In order to characterize the viral agents causing this outbreak, we collected stool or sera (and both for three case) from patients with hepatitis A from many regions throughout Japan and performed genotyping of the VP1/P2A regions of HAV. We then used a multiple-alignment algorithm to compare the nucleotide sequences with those of reference strains. Phylogenetic tree analyses revealed that the 159 HAV isolates were divided into three subgenotypes: IA (137 cases), IB (4 cases), and IIIA (18 cases). The most unique feature of this outbreak was that for most subgenotype IA cases (103 out of 137 IA cases) the sequences analyzed shared 100% homology. Interestingly, the peak week for these IA infections was almost the same nationwide, suggesting that the epidemic of hepatitis A caused by this subgenotype IA strain may have expanded from a single source possibly because of one food-borne or waterborne source that was distributed nationwide at once.

Ongoing increase in measles cases following importations, Japan, March 2014: times of challenge and opportunity.

WPSAR Vol 5, No 2, 2014 | doi: 10.5365/wpsar.2014.5.2.001 www.wpro.who.int/wpsar 1 a Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan. b Department of Virology 3, National Institute of Infectious Diseases, Tokyo, Japan. Submitted: 1 April 2014; Published: 16 May 2014 doi: 10.5365/wpsar.2014.5.2.001 Ongoing increase in measles cases following importations, Japan, March 2014: times of challenge and opportunity

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

Epidemiology of Domestically Acquired Amebiasis in Japan, 2000–2013

Notifications of amebiasis have been increasing in Japan. Using national surveillance data during 2000-2013, reported cases of amebiasis were analyzed. A case of amebiasis was defined as laboratory-confirmed Entamoeba histolytica infection, regardless of presence of symptoms. We described temporal trends and analyzed correlates of asymptomatic versus symptomatic cases based on odds ratios (ORs) and 95% confidence intervals (CIs) using logistic regression. Of 9,946 cases reported during 2000-2013, 7,403 were domestic cases. During this period, the proportion of domestic cases increased from 63% to 85%. Among male cases, majority were middle aged, and from 2008, the number of cases attributed to heterosexual contact surpassed that of homosexual contact. During 2010-2013, increase in notifications was associated with asymptomatic cases, colonoscopy diagnosis, and males with unknown or heterosexual route of infection. Among males, colonoscopy (OR = 31.5; 95% CI = 14.0-71.0) and cases with unknown route of infection, relative to homosexual contact (OR = 2.2; 95% CI = 1.3-3.9), were associated with asymptomatic infections in multivariate analysis. Although the recent rise may have been due to enhanced detection by colonoscopy or reporting, the large number of asymptomatic cases, with reportedly unknown or heterosexual route of infection, has led to a better understanding of amebiasis in Japan and highlights the potential public health concern.

Descriptive epidemiology of varicella based on national surveillance data before and after the introduction of routine varicella vaccination with two doses in Japan, 2000–2017

Routine childhood immunization using two doses of the varicella vaccine was introduced in Japan in October 2014. In this study, we analyzed the data extracted from national varicella surveillance, including pediatric sentinel surveillance from 2000 to 2017 and hospitalized varicella surveillance from the 38th week of 2014 to the 37th week of 2017. Compared with the 2000-2011 baseline data, the number of varicella cases per sentinel decreased substantially by 76.6% overall and by 88.2% among children aged 1-4 years in 2017. Of 997 hospitalized patients, we found a decreasing trend in the number of cases among children aged <5 years. We also found a decreasing trend in the number of cases with complications among children aged 1-4 years. Data on the self-reported transmission sites in 35.5% (354/997) of the hospitalized varicella patients showed that transmission of varicella zoster virus (VZV) occurred frequently in household, at school for young children, in the workplace for adults, and at hospital for all age groups. Data from 29.0% (289/997) of the hospitalized patients with a self-reported source of infection showed that transmission of VZV occurred from a patient with herpes zoster (HZ) in 30.4% (88/289) of cases. Our data demonstrate a substantial decrease in the number of varicella cases in young children following introduction of routine childhood vaccination program with two-dose varicella vaccination in Japan. These data highlight the unique aspects of transmission sites across age groups and the important role of HZ cases in disease circulation.

Prospective Case-Control Study of Risk Factors for Incident Syphilis Infection Among Men Who Have Sex With Men in Tokyo, Japan

Western Pacific Surveillance and Response (WPSAR) is an open access journal dedicated to the surveillance of and response to public health events. The goal of the journal is to create a platform for timely information sharing both within our region and globally to enhance surveillance and response activities. WPSAR is a continuous publication which means articles will be published online as soon as they have completed the review and editing process. Every three months articles will be batched for a print issue. It is a publication managed by the World Health Organization Regional Office for the Western Pacific. IN THIS ISSUE