La grippe est-elle encore le modèle des infections virales émergentes ?

Emerging viral infections are a crucial challenge to the organization of human public health policies. In the past decades, numerous viral pathogens have barged into the field of medicine, being viruses either newly appeared in the population or newly identified or exhibiting unexpected epidemiological properties. Several factors have been reported to promote such emergences, including viral traffic from animals, ongoing viral genetic evolution, host factors, environmental and social changes. As an example, HIV-1 pandemic perfectly illustrates the evolutionary success of a simian retrovirus introduced into the human population as well as its dramatic impact both on the demographic and economic status of many countries. Influenza viruses remain a classic persisting model of emerging pathogens, which is supported by the coalescence of many contributing characteristics, particularly an animal reservoir consisting of birds and mammals and a segmented RNA genome prone to point mutations and reassortments. Two recent examples, the avian flu due to A/H5N1 virus and the pandemic flu due to A/H1N1 2009, show the difficulties both for predicting the outcome of flu emergences and defining the right strategy for their control. Despite their complexity, influenza virus infections provide a permanent incitement to improve our knowledge and monitoring of viral emergences.