Virology and Immunology

Epidemiology and Evolution of Viruses

Sometimes, an old disease reappears in a new clinical form that may often be severe or fatal. These are known as re-emerging diseases. A series of recent emerging infectious disease outbreaks, including the 2014 Ebola virus disease (EVD) epidemic in West Africa and the continuing Zika virus disease epidemic in the Americas, have underlined the need for better understanding of which kinds of pathogens are most likely to emerge and cause disease in human populations. Emerging infectious diseases caused by numerous micro-organisms have been affecting a region, country and sometimes the entire globe from time to time sporadically or in the form of small outbreaks to global pandemic like swine flu. Many diseases which were once considered to be no longer a threat to the public health have once again begun to re-emerge. Many new and emerging RNA and DNA viruses are zoonotic or have zoonotic origins in an animal reservoir that is usually mammalian and sometimes avian. Not all zoonotic viruses are transmissible (directly or by an arthropod vector) between human hosts.  Some infectious diseases seem to be exacerbated by various factors, including rapid urbanization, large numbers of migrant workers, changes in climate, ecology, and policies, such as returning farmland to forests