Infectious Disease Sureillance Center

IDWRMeasles in Japan as of end of week 8 (24 February 2008)

Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan

Both measles and rubella used to be sentinel diseases in Japan until the end of 2007, but have been designated as notifiable diseases since 1 January 2008. This report summarizes the results of measles surveillance and the information of public health measures during the first 8 weeks of 2008.

Epidemiological Information:
Between 1 January and 24 February 2008, a total of 2638 cases were reported from 42 prefectures out of a total 47. The three largest epidemic areas were Hokkaido (n=263), Tokyo metropolitan region [e.g. Kanagawa (n=990) and Tokyo (n=263)], and Kyushu [e.g. Fukuoka (n=334)]. Figure 1 shows the cumulative number of reported cases by each prefecture. Of which, 1,785 cases (67.7%) were clinically-diagnosed cases and 853 cases (32.3%) were laboratory confirmed cases (Fig.2). Breakdown by ages shows that the cases aged between 10 and 29 years account for about 70% of the total cases. Among them, most affected age group was between 15 and 19 (667, 25.3%), followed by between 10 and 14 (560, 21.2%), and between 20 and 24 (339, 12.9%) (Fig.3). As to vaccination status (Fig.4), unvaccinated cases constitute 49.6% (1,309). Cases with one-dose vaccination and two-dose vaccination account for 21.6% (569) and 0.9 % (23), respectively. The rest of the cases, 27.9% (737), reported that their vaccine status were unknown. Especially, majority of the cases aged twenty and above stated that they were not sure whether they had been vaccinated or not (Fig.5). Regarding complications, three cases with encephalitis were reported; 16-year-old female, males in his 20's and 30's. Children aged one or younger constitute 48.3% of the cases with pneumonia (Fig.6). No fatal case has been reported as of 24 Feb, 2008.

In Japan, prefectural and municipal public health institutes (PHIs) report isolation/detection of infectious agents from specimens collected by sentinel clinics and hospitals under the National Epidemiological Surveillance of Infectious Diseases, other medical institutions and health centers. From January to February 2008, 7 PHIs reported 39 measles virus isolation/detection. Of these, 5 of 5 strains genotyped were D5 (see

Public Health Measures:
At national level, the information regarding recent situation of measles and on the importance of vaccination have been frequently provided to the public through various tools including mass media and the website of Infectious Disease Surveillance Center (IDSC) at (Japanese). Technical guidelines for public health authorities and schools were prepared in the websites. Local health officials in some affected areas such as Yokosuka city (Kanagawa prefecture), have implemented mass immunization campaign mostly using measles-rubella (MR) vaccine targeted at children and teenagers. School closures were occasionally reported as well.

On 12 February 2008, the first meeting for measles elimination from Japan, organized by Ministry of Health, Labour and Welfare (MHLW), was held in Tokyo. Representatives participated in it from MHLW, Ministry of Education, Culture, Sports, Science and Technology (MEXT), local health officials, local boards of education, Japan Medical Association, pediatricians, vaccine companies, patients' associations, parents, the media, IDSC, and so on. National goal of measles elimination by year 2012 was agreed at the meeting. It was also agreed that because of accumulated susceptible population of teenagers, routine vaccination, mostly using MR vaccine, would be started from this April 2008 targeting age-cohorts of both 13 years of age and 18 years of age for the next five years, in addition to the current two age-cohorts of 1 years of age and one year prior to entering to elementary school. Other strategies include rapid reporting of adverse events of the vaccination, introduction of case-based surveillance and strengthening outbreak response. At local level, regional meetings, hosted by MHLW and co-hosted by IDSC, regarding measles elimination had been held nationwide in February 2008.

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