An emerging disease is defined as a new infection caused by changes or evolution of a pathogen or an existing parasite, manifested through a change of host, vector, pathogenicity or strain. The term also applies to the appearance of an infection or disease which has not yet been reported. A disease is said to be re-emerging if a known disease erupts in a new geographical context, broadens its host range or makes significant progress in terms of prevalence (OIE).
Of the emerging diseases, more than 60% are zoonoses (Jones et al., 2008, Nature 451:990-3). Emerging zoonoses represent a growing threat to international public health.
