The discovery of a new virus in two Wisconsin babies thought to be victims of sudden infant death syndrome has triggered questions about how often such mysterious tragedies might be due to infection.
The virus was recently identified in Japan and has not been found in the United States before now.
Officials do not know whether it killed the babies, who were sick before they died and had signs of disease in their lungs.
But infectious diseases can masquerade as SIDS, and few cases get the kind of testing that would reveal viruses as the culprit.
The Wisconsin findings should prompt more research into how many cases may be due to these types of viruses, said Dr Mark Pallansch, who identified the new germ at the federal Centers for Disease Control and Prevention after a Milwaukee virologist detected it.
“At this stage we just have very little information about the involvement of these viruses in human disease,” he said
SIDS – also called “cot death” for the devastating way it is usually discovered – is a catch-all term for unexplained deaths in children less than a year old.
Brain or breathing abnormalities, genetic mutations and birth defects are possible causes. The risk rises if babies live with smokers, are put to sleep on their stomachs, or are bundled in too many clothes or covers.