[Severe acute respiratory syndrome (SARS). Lesson and challenges].

After four months of silence before a new incursion of severe acute respiratory syndrome virus (SARS), world wide investigators specially from Asia had have to face a coronavirus capable of great spreading and inducing high morbidity. The source and the capacity of this virus to associate with other opportunist microorganisms to induce progression of the disease, remain unclear. The comparison of the genomic sequence of different strains has generated discrepancies as for if the SARS epidemic arose as an unique outbreak or it was produced for more than one genotype.