Effects of Superspreaders in Spread of Epidemic

1. Introduction Spread of epidemic can be regarded as diffusion or random walk of disease on the fixed discrete elements. Severe Acute Respiratory Syndrome (SARS) which spread around the world during 2003 is no exception. It is now believed that the sharp increase and decrease in the number of SARS patients was caused by the existence of superspreaders. According to WHO, the patients are defined as superspreaders if they infect more than 10 people. However, the cause why such superspreaders appeared is not yet clear. Possible origins of appearance of them might be (i) the superspreaders have constitutional or hereditary strong infectiousness or (ii) the superspreaders have many social connections. In this presentation, we investigate the effects of such superspreaders on diffusion process, and show that the basic reproductive number plays a critical role.