[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. However, this fact is secondary to the imminent threat that was controlled in August of 2003, after affecting 8.422 individuals, but before which we should be remain alert, since it is clear that the end of the SARS is not yet here; and that the appearance of a single case can mean the beginning of a new wave, joining the outbreak of other diseases such as the avian flu. In this regard, it is very important to know the epidemic bases of morbid-mortality of SARS and to keep a world wide surveillance in order to detect possible further cases.