New Emerging Viruses

Newly emerging viruses such as the Ebola virus, severe acute respiratory syndrome (SARS)-, Middle East respiratory syndrome (MERS)-coronavirus, and the avian influenza virus are serious threats to public health and have become a global concern. The swine flu pandemic which occurred in 2009 reminded us of the Spanish flu that killed over 40 million people. Newly emerging viruses could be either a novel previously undescribed virus or a variant of a previously known virus. Examples of the novel viruses include HIV, the Ebola virus, and SARS viruses. Variants of previously described viruses are also called “remerging viruses.” They are mutants of known viruses but cause new epidemics with considerable virulence. The influenza virus that caused the 2009 swine flu pandemic was a variant of an existing virus.