Usefulness of internet-based surveillance system for real-time detection of influenza outbreaks in Japan

Background:  Because of the outbreak of 2009 H1N1 influenza, construction of a surveillance system has become top priority, as correct notion of the latest trend and sharing of information within the community, contribute significantly to the design of preventive measures and system for treatment for the infection.  

Objective: The objectives are to promptly grasp and disclose the epidemic trends of the influenza virus through the internet, provide community members with accurate information, and apply the information to establish a system for treatment and prevention.

Methods: 291 medical facilities and every school in Gifu Prefecture (700, including elementary, junior high and high schools) were covered in the study.  In medical facilities, cases were classified into two groups: new patients who were diagnosed as Type A or Type B influenza using rapid antigen testing, and those who showed negative results or did not take the rapid test but showed symptoms that strongly suggest influenza.  These cases were further classified according to age and gender, and the data was fed into the web daily at 20:20.  In schools, the health nurse in charge at each school entered the status of school, year or classroom closure, as well as the number of absent students daily at 13:00.  The system ran on a trial basis starting September 1st, 2009, and was open to the public on September 25th.   

Results: During the 11 weeks from September through November, 15,677 patients were diagnosed as Type A, 202 as Type B, and 6,283 as others (diagnosed based on symptoms), totaling 22,162.  As of November 14th, the number of patients in one week at a fixed point across the Prefecture was 14.6. With regard to schools, 31.2% (217/695) of all elementary, junior high or high school was closed either at the classroom, year or school level.  Average number of access to the public homepage in a week was 25,000 in November. The most viewed date was about 5,000/day and the time zones with most access were from 8 am to 12 am and 8 pm to 10 pm.    

Conclusions: Throughout Japan, there is no other prefecture that is disclosing this kind of surveillance data everyday by internet, collected from medical institutions and educational facilities in the region.  Since this system enables us to catch immediate trends of the situation about epidemic, it is highly expected to make it easier to prepare for a new system how to deal with the after hour patients or patients who need medical care on holidays, or to predict and get the number of beds needed for hospitalized patients in the future, or to deal smoothly with educational facilities in the region. Now, we are planning to expand this system to other infectious diseases such as measles. This system allowed us to provide valuable information to medical and educational institutions and this information appeared to be utilized by many residents in the region especially in the field of diseases like influenza which the trend of epidemic shows dramatic processes.