• bacterial toxins;
  • Escherichia colr;
  • sudden infant death

Abstract The possibility that most cases of sudden infant death syndrome (SIDS) are caused by a transmissible agent is explored. A hypothesis of causation is developed using pathological and epidemiological data and our microbiological findings. The nature and distribution of vascular damage together with the consistent finding of liquid blood, in addition to the epidemiological features of SIDS, form the basis of the hypothesis that a bacterial toxin is a likely single cause of most cases of the syndrome. Future research ideas and a new definition of SIDS are proposed.