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◆ Measles in Japan from 1st to 7th epidemiological week, 2019 (as of February 20, 2019)

March 5, 2019

Measles is a viral disease characterized by high fever, rash, and catarrh (i.e., cough, coryza and conjunctivitis). It is highly contagious mainly by airborne transmission. Complication of measles such as pneumonia and encephalitis may lead to death. However, vaccines can prevent measles. Japan aims to maintain measles elimination status which had been verified internationally in March 2015, based on “Guidelines for the Prevention of Specific Infectious Diseases: Measles” issued by the Japanese Ministry of Health, Labour and Welfare in December 2007.

The number of measles cases reported was between 1-9 cases per week since the 35th week of 2018. However, they have increased rapidly (22-47 cases per week) since the 2nd week of 2019, and have comparatively increased faster than the cases identified during Okinawa outbreak in April 2018, as of the 7th week of 2019. This report is to provide recent epidemiological situation of measles in Japan based on National Epidemiological Surveillance of Infectious Diseases (NESID).

In Mie Prefecture where outbreak occurred from the beginning of 2019, multiple measles cases (secondary infection) were reported from the participants of a meeting which was held in December 2018. After that, cases were reported from among contacted persons such as family members, or at hospitals and schools. In Osaka Prefecture, where they reported more cases than Mie Prefecture, multiple outbreaks have occurred. It was reported that the sales person of shopping facility had measles, and the patient spread measles to colleagues and customers in February 2019. There are other measles cases reported in several prefectures, and press releases followed.

Tuberculosis and Infectious Diseases Control Division of the Health Services Bureau at Ministry of Health, Labour and Welfare has alerted the local authority that there are some possibilities of new measles cases in wide range of areas due to mobility of patients (Regarding alert associated with increase of reported number of measles cases on February 18, 2019 (request for cooperation).

The number of reported measles cases was 221 in the 1st-7th week of 2019 (as of February 20, 2019). Of those, 197 cases (89%) were laboratory confirmed (158 measles, 39 modified measles). 108 males, 113 females, and median age was 23 (range 0-72). The numbers reported cases by prefectures are: 77 Osaka, 49 Mie, 20 Aichi, 14 Tokyo, 9 Kyoto, 8 Kanagawa, 7 Wakayama, 5 Gifu and Hiroshima, 4 Chiba, 3 Hokkaido, Ibaragi and Shizuoka, 2 Tochigi, Saitama, Shiga, Hyogo, Nara and Okinawa, 1 Iwate and Kumamoto.

The probable infected areas are 170 Japan (13 unknown prefecture) and 33 outside Japan (13 Philippines, 8 Vietnam, 3 Myanmar, 2 Maldives, 1 Republic of Korea, Cambodia, Sri Lanka and Malaysia, 2 Sri Lanka/Maldives, 1 Thailand/Laos), 3 Japan/overseas (2 Aichi/Philippines, 1 Aichi/New Caledonia) and 15 unknown Japan nor overseas. As for vaccination history, 84 (38%) had not been vaccinated, 72 (33%) unknown, 38 (17%) received first dose and 27 (12%) second dose.

Among 27 who received second dose, 15 had mild and atypical measles (modified measles).

Among 84 who had not been vaccinated, 81 had typical measles, and out of them 70 were laboratory confirmed.

As of February 21, 2019, 73 cases of measles virus genetic information were sent to the Infectious Agents Surveillance System. The genotypes detected were: 69 (95%) D8, 3 (4%) B3 and 1 (1%) Not typed.

Measles still remains endemic in many countries. To prevent measles virus from entering into Japan, it is recommended that travelers who plan to go abroad should check their vaccination record and receive vaccine as necessary.

For prevention against measles from spreading in Japan, individual protection and maintenance of herd immunity is crucial. To do so, it is most important to enforce second dose vaccination by using measles and rubella combined vaccine. In addition, early detection of measles case and rapid response is indispensable. The other important factors are: appropriate diagnosis, rapid investigation and response through contact tracing with cooperation of related organizations right after even one case is reported, and to inform local medical facilities and advocate local residents for prevention. Information sharing among related local authorities is important in case of possible diffuse outbreak.

Especially in the area where measles case is reported, infection control should be strengthened in the medical facilities. The vaccine records of all medical staff including clerical staff should be checked and recommended vaccination as needed. Person who develops measles like symptoms such as fever and rash after having contact with measles suspected cases should make a phone call to medical facility before presenting himself/herself and inform of possibility of measles, in order to prevent secondary infection.

Measles is transmitted by airborne and can cause serious complication. Current increasing number more than the average year in Japan, increases the risk of developing serious measles cases. It can also be the great concern to Japan’s achievement of measles elimination. It is expected that people move more widely due to coming season of house-moving and tourism in spring, assuming measles remain prevalent. Since measles is a vaccine preventable disease, strict caution and response to the spread of infection is crucial.

 

Infectious Disease Surveillance Center of National Institute of Infectious Diseases

 

Current situation of measles can be referred to the information indicated below (Citation date on February 21, 2019): (Note: all in Japanese)

Copyright 1998 National Institute of Infectious Diseases, Japan