Chinese HFRS incidence data from 1975 to 2008 was obtained from the Chinese Center for Disease Control and Prevention. All HFRS cases were initially diagnosed by clinical symptoms. Patient blood samples were also collected and sent to local Centers for Disease Control and Prevention (CDC) laboratories for serological confirmation. Finally, data were collected by case number according to the sampling results. There might be admission rate bias in the disease report, but this has been reduced as much as possible. In China, HFRS is a nationally notifiable disease and hospital physicians must report every case of HFRS to the local health authority within 12 hours. Local health authorities later report monthly HFRS case totals to higher the national level CDC for surveillance purposes. Due to mandatory reporting, it is believed that the degree of compliance in disease notification over the study period was consistent.