Ken Osaka

Testing a symptom-based surveillance system at high-profile gatherings as a preparatory measure for bioterrorism.

We tested symptom-based surveillance during the G8 conference in 2000 as a means of detecting outbreaks, including bio-terrorism attacks, promptly. Five categories of symptoms (skin and haemorrhagic, respiratory, gastrointestinal, neurological and unexplained) were adopted for the case definition of the surveillance. The surveillance began I week before the conference, and continued until 1 week after the conference ended. We could not detect any outbreaks during this surveillance. Compared to the existing diagnosis-based surveillance system, symptom-based surveillance has the advantages of timeliness and simplicity. However, poor specificity and difficulties in determining epidemic threshold were important limitations of this system. To increase the specificity of surveillance, it is essential to incorporate rapid laboratory diagnoses into the system.

Spatio-temporal modelling of the HIV epidemic in Japan based on the national HIV/AIDS surveillance

In this paper, we develop a multiregion epidemic model in order to provide the basic information on local HIV epidemic states in Japan. By considering the previous efforts of national epidemic projections in Japan, we statistically calibrate a model by employing an estimation method that allows the inclusion of geographically varying parameters. Using this model, we present a geographical projection of local epidemics until 2015 by examining geographical variations in future epidemic growth and spatial relationships in HIV transmission. We also discuss the implications of planning preventive measures and improvement in the Japanese HIV/AIDS surveillance system based on analytical results.