Pandemic influenza (H1N1) situation report in Japan - update 14
September 11, 2009


Domestic situation in Japan

According to the National Epidemiological Surveillance for Infectious Diseases in Japan, the number of reported cases of the Influenza like Illness (ILI) have been increasing in the 35th epidemiologic week (August 24-30, 2009) (Figure 1). The number of cases reported per sentinel* in Japan was 2.52, which has slightly increased compared to previous week (2.47 per sentinel). Based on this number, ILI patient is estimated to be approximately 140,000 (95% Confidence Interval 130,000-160,000) nationwide. 



Although the estimated number of ILI cases has decreased compared to the previous week, Okinawa Prefecture had the highest reported cases per sentinel (36.00). This number indicates that current influenza activity in Okinawa is similar to the seasonal influenza activity observed in winter season. The next highest number was reported from Oita Prefecture in Kyushu region (3.72) and Osaka Prefecture (3.08). 

  According to Infectious Agents Surveillance Report, most of the influenza cases detected/isolated during the week 19 through 35 were pandemic influenza A(H1N1) virus (Figure 2).



* The number of sentinel clinics and hospitals is decided depending on the relative population of the jurisdiction of each public health center and on consideration enabling comprehend the incidents in the whole area of the prefecture. The influenza sentinel points consist of approximately 3,000 pediatric hospitals/clinics and 1,800 internist hospitals/clinics around the country.