What infectious diseases are being reported in the parts of Japan you care about?
A city you would like to visit in Japan. A place you have traveled to before. An area where family or friends live.
This time, we are looking at provisional Infectious Disease Weekly Report (IDWR) surveillance data released by the Japan Institute for Health Security (JIHS) for September 28–October 4, 2026 (Week 40).
Explore infectious disease reports across Japan
Choose a disease and open a region or prefecture that interests you to see its figures. The map lets you switch between Japan as a whole, nine regions, and all 47 prefectures.
Why not take a look at a place you are curious about?
Reports across Japan for September 28–October 4
Across Japan, the number of reported cases per sentinel site during this week was 11.35 for influenza and 1.51 for COVID-19. Use the buttons on the card to see the other diseases.
“Cases per sentinel site” means the number of cases reported by each participating medical facility. It does not represent the total number of people infected in Japan.
What I noticed while making the map
The latest map shows several differences from the previous week. Nationwide, influenza rose from 7.17 to 11.35 cases per sentinel site. Okinawa Prefecture fell from 42.50 to 37.07 but remained the highest in the country.
Nationwide, COVID-19 rose from 1.25 to 1.51, infectious gastroenteritis from 2.22 to 3.28, and RSV infection from 0.84 to 1.03.
Pertussis reports rose nationwide from 51 to 83, while measles reports fell from 2 to 0, with none reported this week. We will continue to follow the regional patterns.
From a city you would like to visit in Japan to somewhere you have been before, shall we explore together what is changing in the places that interest you?
Explore data for all infectious diseases (108 categories) →
Source: Japan Institute for Health Security (JIHS), “IDWR Provisional Data, Week 40, 2026” (published October 13, 2026; accessed October 13, 2026).
Sources for the comparison with the previous week: the official weekly case-count and sentinel surveillance CSV files for IDWR Provisional Data, Week 39, 2026 and Week 40.
- These figures are provisional and may be revised later. The Week 40 weekly report PDF had not yet been published at the time this article was prepared.
- Map colors show reporting patterns. They do not indicate an individual’s risk of infection or how safe an area is.
- For COVID-19, 2019 is not applicable; the 2021 figure covers notifications recorded in NESID under the mandatory reporting system for all diagnosed cases; and the 2026 figure is based on cases per sentinel site. Percentage changes across these years are not calculated.