Introduction of Emerging Infectious Diseases

Emerging infectious diseases (EIDs) refer to contagious diseases newly appeared, or with drug resistance, whose incidences have been rapidly increasing and are likely to further rise in the future. EIDs are usually discovered in three ways. Firstly, some existing diseases are ascertained as EIDs due to the recent discovery of pathogens. Secondly, previously considered noninfectious diseases are identified contagious as a result of new etiological findings. Thirdly, new infectious diseases are incurred by various complicated reasons such as evolution of pathogens. Due to their uncertainty and unpredictability, EIDs could result in high mortality and great impacts on social stability and economic development as people are unable to react immediately and take specific preventive or control measures. Therefore, EIDs have become a major public health problem worldwide. Cases in point are the epidemics of SARS in 2003 and H7N9 avian influenza around 2006, which have eloquently demonstrated their great threats to human health, society, and economy. In the coming twenty-first century, contagious diseases are expected to remain as a crucial public health concern for countries around the world.