Since 23 April 2007, there have been 691 confirmed cases of measles in Japan. The outbreak is occurring mainly in the Kanto area including Tokyo, Kanagawa, Saitama and Chiba Prefectures. More than 80 percent of cases are under 29 years of age.
The scale is much smaller than an outbreak in 2001 when over 100,000 cases and between 20-50 deaths were reported.
Many universities and schools in the region have suspended classes to help prevent spread of infection.
Japan stopped using the MMR immunisation against measles, mumps and rubella in 1993 due to problems with the mumps part of the vaccine. The strain of mumps virus (Urabe) used in the local manufacture of the vaccine caused cases of viral meningitis (the MMR vaccine used in other countries, including the UK, was not affected by this problem). The MMR programme was replaced with a one dose vaccination programme of single jabs of measles and rubella vaccines.
Measles rates in Japan are relatively high compared to other industralised countries. Although the Immunisation coverage rate of one dose vaccination in Japan is high at 97% in children aged 2-10 years and 95% in 11-20 year olds, 5% of recipients either do not acquire immunity or lose immunity to the measles virus after the single dose, leaving them susceptible to infection. In line with many other countries, including the UK, a two dose vaccination programme was introduced in 2006. However at present, the coverage is less than 40%.
It is advised that visitors to Japan from the UK should confirm that any children travelling have received their recommended doses of MMR at 12-15 months of age and again pre-school around 4-5 years, while unimmunised adults who have not had the disease themselves may consider vaccination if thought to be at risk.
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