麻疹ウイルスの感染経路と現状

Keiko Tanaka-Taya

A large-scale national measles epidemic occurred among mainly in teenagers and young adults in 2007. MHLW announced ''Special infectious disease prevention guidelines for measles'' (issued on 28 December 2007; Revised issued on 30 March 2013), and Japan decided the elimination target year was fiscal year (FY) 2015. In 2008, it continued to be a large-scale nation epidemic exceeding 10,000 cases, and a large number of 0 to 1 year old infants, teenagers and young adults were suffering. Many cases were unvaccinated, single dose vaccination or unknown vaccination history. The number of measles cases has declined dramatically since 2009, and the measles virus of genotype D5, which was the indigenous strain in Japan, was not detected at the end of May 2010. Regional epidemics were approved in 2011 and 2014, starting from imported cases from overseas, but it ended early. Since 2006, a two-dose routine vaccination regimen of measles rubella combined (MR) vaccine has started, moreover in the 5 years from fiscal 2008, the second dose of MR vaccine for junior high school students and high school students was periodically inoculated and immunization strengthened for teens was done. As a result, antibody positive rate of 95% or more is maintained in all age groups over 2 years old. In March 2015, Japan's measles elimination was certified by the WHO Western Pacific Regional Office. In 2017, outbreaks occurred in adults originating from imported cases from Asia or Europe, but early termination declarations have been made by aggressive measures by local public health centers/institutes. The annual number of reported cases after measles elimination certification is less than 200 cases.