Abstract
WHEN a previously well baby dies suddenly and unexpectedly, the cause of death is often obscure. In the past it was usually assumed that death was due to unnatural causes particularly mechanical asphyxia, but as a result of studies made in the last decade,1-7few continue to hold this opinion. Although it is now generally considered that a specific bacterial cause can be ruled out, there is much to suggest that what has been called sudden unexplained death in infancy may be related to infection possibly from one of a number of different viruses. Thus its peak age and seasonal incidence parallel that of acute respiratory tract infection in infancy; in many instances there is a history of a "cold" in the two to three days that preceded death; moreover, evidence of viral invasion of the respiratory tree is frequently noted at postmortem examination. However, it has been pointed