Infectious Disease Sureillance Center

IDWRMeasles update in Japan as of end of week 23 (10 June 2007)

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

Sentinel Surveillance:

Between 1 January and 10 June 2007, a total of 1529 measles cases from 3000 pediatric sentinels have been reported nationwide. 204 cases were reported in 23rd epidemiological week (from 4 to 10 June). Breakdown of new reported cases are as follows; cases reported from 30 prefectures; 114 cases from southern Kanto area (Chiba, Kanagawa, Saitama and Tokyo), 29 cases from northern part of Japan including Miyagi and Hokkaido. The number of reported case from Chiba is still increasing. Characteristic age distribution continues; fewer cases are seen among 0 to 4-year-old (N=568, 37.1%) compared to average year (55 to 67%) and more cases are reported from 10 to 14-year-old (N=470, 30.7%) compared to average year (5 to 15%).

Regarding adult measles (cases of 15-year-old and older), between 1 January and 10 June 2007, a total of 525 cases have been reported from 450 hospital sentinels; 183 cases from Tokyo, 71 cases from Kanagawa, 53 cases from Miyagi and 36 cases from Saitama. Approximately 90% of the cases are reported from the group under 35-years-old. In 23rd epidemiological week, 50 new cases have been reported from sentinels. Numbers have decreased two weeks in a row.

School closure:

According to the Ministry of Health, Labor and Welfare, between 1 April and 9 June 2007, a total of 252 schools were closed completely (187) or partially (65) due to measles outbreak. Fifty-eight percent of them (146) were high schools (73) and colleges/ universities (73). Approximately half of them were reported from Kanto area including Tokyo.

Vaccination status of the cases:

The result of a voluntary surveillance of measles case (Mashin hassei database < >) indicated that, between 1 January and 4 June 2007, approximately 22% of the cases, who were 12-month-old or older, have the history to have single dose of measles-containing vaccine in the past.

Reported exported measles cases from Japan:

According to media reports, measles cases derived of this outbreak in Japan have been reported from Canada, the United States, and Taiwan.

Severity of the epidemic:

Three cases of encephalitis related to measles have been reported in 2007; one in the teens and the others in the twenties. No new case was reported in week 23.

Virus isolated:

According to the local public health laboratories, 80 out of 82 sequenced measles viruses have been identified as D5 strain.

Public Health measures:

  • Information regarding the recent situation of measles epidemic has been rapidly provided to the public.
  • Public sensitization has been conducted regarding the importance of the vaccination, especially to the people who are at highest risk (those who have had neither measles infection nor vaccination in the past). Routine vaccination, especially the first dose, was enhanced.
  • As of 16 May 2007, 37 out of 131 local governments nationwide reported that they have started notifiable surveillance system for measles cases.
  • 500 000 doses of measles-containing vaccine and 600 000 diagnostic kits will additionally be supplied to healthcare facilities and diagnostic laboratories by the end of June 2007.
  • On 14 June, the series of discussion regarding vaccine preventable diseases have been started in the special committee in the MHLW. The strategy of measles elimination from Japan is one of the important agendas.

(2007/6/25 IDSC)

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