[Nipah and Hendra viruses : emerging zoonotic pathogens]

Emerging new viruses present an enormous challenge in understanding their aetiology, pathogenesis and epidemiology. In the last decade two new viruses : Nipah virus in Malaysia and Hendra virus in Australia crossed species barrier from flying foxes to infect humans. While Hendra virus mainly induced pulmonary disease, Nipah virus provoked encephalitis with 40-70 % of mortality, causing important health and economic problems. Based on the similar genome structure, these 2 viruses are classified in a new genus, Henipaviruses, within the family of Paramyxoviridae and both are ranked internationally as biosecurity level 4 agents. Recent studies on the virulence, host range and cell tropism of these human pathogens provide more insight into unique biological properties of the emergent zoonotic viruses.