Infectious Disease Sureillance Center

IDWRMeasles update in Japan as of end of week 25 (24 June 2007)

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

Sentinel Surveillance:

Between 1 January and 24 June 2007, a total of 1837 measles cases from about 3000 pediatric sentinels have been reported nationwide. During the week 25 (from 18 to 25 June 2007), there were 132 newly reported measles cases. The number of reported cases per week peaked at week 23 and is decreasing, but that in Osaka prefecture is still increasing. The outbreak started from Kanto area including Tokyo and has spread to the rest of the country. Fewer cases are seen among 0 to 4-year-old (N=681, 37.1%) compared to those in the average year (55 to 67%) and more cases are reported from 10 to 14-year-old (N=571, 31.1%) compared to those in the average year (5 to 15%).

 Regarding adult measles (cases of 15-year-old and older), between 1 January and 24 June 2007, a total of 613 cases has been reported from about 450 hospital sentinels. As is seen in pediatric cases, the number of reported cases already peaked and is now decreasing, but that in Osaka prefecture is still increasing. As for the age distribution, 29.9% (N=183)of cases are from 20 to 24-year-old, 25.1% (N=154) are from 15 to 19-year-old, and 22.5% (N=138) are from 25 to 29-year-old.

Severity of the epidemic:

As of 24 June 2007, five cases of encephalitis related to measles have been reported; one in the teens and the others in the twenties.

Virus isolated:

According to the local public health laboratories, almost all of the sequenced measles viruses (N=123) have been identified as D5 strain. An H1 strain has been identified from one patient who came back from abroad 5 days prior to disease onset. More information of isolated virus, including other diseases, is available at

Public Health measures:

-Information regarding the recent situation of measles epidemic and the importance of vaccination has been rapidly provided to the public. 

-The discussion regarding the strategy of measles elimination from Japan is ongoing in the special committee for vaccination organized by the MHLW.


Because of the decreasing trend of measles epidemic, the English version of “Measles update (2007) in Japan” will temporarily be suspended from the next week. Infectious Disease Weekly Report (IDWR) including the result of measles surveillance will be available in Japanese language at the IDSC/NIID website (

.(2007/7/17 IDSC)

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