Health officials in Japan say as of Monday more than 170 people across the country have been infected with measles. The outbreak began in the southwestern prefecture of Okinawa in March.
The National Institute of Infectious Diseases said on Tuesday that 99 people were infected in Okinawa, 23 in Aichi, central Japan, and 2 in Tokyo.
17 people have tested positive for the viral disease in Fukuoka, southwestern Japan.
The officials said the number of cases could increase due to the spring vacation period in late April and early May, when large numbers of people travel around the country.
The disease has an incubation period of 10 days to 2 weeks.
A senior institute official said the outbreak is still contained, but that caution is called for.
The official said people in their 20s to 40s are at high risk of infection. She called on them to get vaccinated, especially if they work in medical institutions, schools or childcare facilities.
