Infectious Disease Sureillance Center

IDWRMeasles update in Japan as of end of week 35 (2 September 2007)

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

Sentinel Surveillance:

Between 1 January and 2 September 2007, a total of 2525 measles cases from about 3000 pediatric sentinels have been reported nationwide. During the week 35 (from 27 August to 2 September 2007), there were 67 newly reported measles cases from 22 prefectures. The number of reported cases per week per sentinel in this week was 0.022 (Fig. 1). It peaked at week 21 (0.071) and was decreasing until week 32 (0.017). But, from week 33 to 34, there was a slight increase of the reported cases per sentinel (0.021 to 0.023), which was mainly attributed from western part of Japan; Osaka and Fukuoka prefectures. The outbreak initially started from South-Kanto area including Tokyo, Saitama, Chiba, and Kanagawa prefectures and has spread to the rest of the country. Fewer cases are seen among 0 to 4-year-old (N=986, 39.0%) compared to those in the average year (55 to 67%) and more cases of 10 to 14-year-old (N=740, 29.3%) are reported compared to those in the average year (5 to 15%).

Regarding adult measles (cases of 15-year-old and older), between 1 January and 2 September 2007, a total of 805 cases has been reported from about 450 hospital sentinels. As is seen in pediatric cases, the number of reported cases already peaked at week 21 and is now decreasing (Fig. 2), but those in Osaka and Fukuoka prefectures are still increasing. As for the age distribution, 27.3% (N=220)of cases are from 20 to 24-year-old, 27.1% (N=218) are from 15 to 19-year-old, 22.4% (N=180) are from 25 to 29-year-old, and 11.7% (N=94) are from 30 to 34-year-old.

Fig. 1. Reported cases of measles per pediatric sentinel per week from 1 Jan 1997 to 2 Sep 2007, Japan

Fig. 2. Reported cases of adult measles per hospital sentinel per week from 1 Apr 1999 to 2 Sep 2007, Japan

Overall, reported number of measles is decreasing in national level. But, in some areas such as western part of Japan, epidemic is still ongoing or even worsening.

Severe cases of measles:

As of 2 September 2007, eight cases of encephalitis related to measles have been reported; four in the teens and the others in the twenties. No related death has been officially notified.

Virus isolation:

According to the local public health laboratories, almost all of the sequenced measles viruses (N=265) have been identified as D5 strains. An H1 strain has been identified from one patient who came back from China 5 days prior to disease onset. More information of isolated virus, including other diseases, is available at

Vaccine status of the cases:

The result of a voluntary surveillance of measles case (Mashin hassei dababase at indicated that, between 1 January and 17 September 2007, approximately 35.7% of the cases, who were 12-month-old or older, had the history to have had at least single dose of measles-containing vaccine(s) in the past.

Public Health measures:

-Information regarding the recent situation of measles epidemic and the importance of vaccination has been provided to the public through various tools including the website of Infectious Disease Surveillance Center (IDSC) at
-The necessity of measles elimination from Japan by year 2012 has been agreed in the special committee for vaccination organized by the Ministry of Health, Labour and Welfare (MHLW). Basics of its strategy from April 2008 are; 1) supplementary immunization for five years targeting at teens, 2) introduction of case-based surveillance instead of reports from only sentinel clinics/hospitals, 3) preparation of rapid response against measles outbreak and 4) establishment of other necessary system to support national and local activity towards measles elimination.


For further question to IDSC about measles in Japan, please contact either Dr. T. Sunagawa in Intelligence and Policy Planning Division (Division1) at , Dr. Y. Yasui in Surveillance and Information Division (Division2) at , Dr. K. Taya in Immunization Program Division (Division3) at , or Dr. N. Okabe, the director of IDSC at .

(2007/9/19 IDSC)

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