Mark Parascandola's well-researched article, "Scientists, Families, and Courts Clash Over the Elusive Causes of Autism," in the Summer 2004 issue of Cerebrum, may have confused your readers. He failed to make clear that the measles-mumps-rubella (MMR) vaccine never contained the ethylmercury-based vaccine preservative thimerosal. Although we are confident that, given his expertise, Parascandola's omission of this distinction was inadvertent, it is important to clarify the issue for your readers, given the widespread, often-alarmist media coverage of the issue of the role that pediatric vaccines might play in the development of autism.
The hypotheses of thimerosal-induced autism usually invoke a theoretical genetic inability on the part of a sensitive sub-population of children to detoxify thimerosal. By contrast, the 1998 Wakefield study published inLancet addressed a completely different and unrelated mechanism of autism induction, namely, that MMR immunization evokes an inflammatory bowel response; the ensuing epithelial damage supposedly causes toxins to leach through the gut wall into the bloodstream and be transported to the brain to cause damage presenting as the clinical syndrome of autism.
Many rigorous epidemiological studies have failed to confirm any association whatsoever between MMR and autism. They should have put to rest the MMR-autism debate. Unfortunately, however, the MMR-autism mythology has terrified parents, so much so that MMR vaccination coverage has begun to decline, particularly in the United Kingdom. This has led to outbreaks of potentially deadly diseases. In effect, the priority of parents to protect their children against measles has been trumped by misguided efforts to protect them from autism. Parents who avoid having their children vaccinated are putting their children at risk of contracting a host of potentially deadly, vaccine-preventable diseases now on the rise, including polio, diphtheria, and pertussis.
Public health and medical professionals can help to allay unwarranted fears by being as explicit as possible when writing for a mainstream audience on subjects such as vaccine safety. Thus, while Parascandola's article was informative, we must be vigilant against assuming that readers are savvy as to the nuances of epidemiology. Those with genuine knowledge of the issues must be careful not to unintentionally add to the activist- and media-generated confusion, which, by further frightening parents, could increase the toll of vaccine-preventable illness and deaths.
Aubrey N. Stimola, Research Associate
Gilbert Ross, M.D., Medical Director
The American Council on Science and Health
New York, NY