National Centers for Health Statistics show that the death rate from SIDS, classified as a natural cause of death, is 0.5% although some experts believe the rates are much higher.

Australian researchers have suspected that some cases of sudden infant death syndrome (SIDS) may be caused by the bacterial infection Staphylococcus aureus (S. aureus), which can produce lethal toxins. An infants body may not be able to deal with these toxins, which could lead to sudden death.

Bacterial infection Staphylococcus aureus (S. aureus) has not previously been considered as a possible cause of SIDS but the researchers from the Women's and Children's Hospital in Adelaidehave found that in some SIDS cases the bacteria S. aureus was implicated as they are sometimes found in sites which are normally sterile such as the heart blood, spleen or cerebrospinal fluid.

After realizing the presence of the bacteria in the normally sterile inviroment, the Adelaide researchers decided to conduct a study in which they reviewed the autopsy records of 130 infants who died from SIDS - 32 of whom from sudden unexpected death from infection (SUDI) and 33 from a non-infectious cause such as an accident.

The study has showed that infants who died from a non-infectious cause rarely had bacteria growing at normally sterile body sites, whereas the SIDS and SUDI infants often had microbes, including potential pathogens, present in these sterile sites. Over 10% of SIDS infants and 18% of SUDI infants have been found to harbour the microbe S. aureus in a normally sterile site but the bacteria were not found in cases of accidental death.

Coliform bacteria are found in the lower intestinal track and in feces, and are used as an indication of levels of sewage contamination and the researchers say the sterile site microbes yielded no growth in 45.4 percent of accidental death cases, 43 percent of SIDS cases, and 28.1 percent of SUDI cases.

They suggest that microbes isolated in SIDS babies may play a role in death.

Although there are precautions parents can take to reduce the risk of their child dying of SIDS, which include not smoking during or after pregnancy, breastfeeding, making sure babies sleep on their back and are not too hot or too cold, and not letting the baby share a bed with someone else, especially if that person is a smoker, or is affected by drugs or alcohol, the reality is that perfectly healthy babies, where all precautions have been taken to ensure their safety, still suffer from SIDS and die in their sleep.