I am a parent who knows the pain and guilt that follows when an infant suddenly dies.

Your article "Sudden Infant Death Reexamined" Health Focus, July 16 stirred anger. I was shocked to read that Dr. Frederick Mandell, clinical professor at Harvard's Medical School and vice chairman of the National SIDS Foundation, favors pacifying parents.

It is true that the parents/guardians need support and comfort during this tragic and trying period; however, what they also need are answers to the questions of why and how.

No parent wants to take on the guilt of "neglect" or "accident." I am convinced that a parent would rather know the truth of the cause, eventually, rather than have the truth "sugar-coated" or "swept under the rug" by an examiner to ease their conscience.

Labeling an infant's death as SIDS without an in-depth investigation of some kind (an autopsy alone, in this case, is not an in-depth investigation) seems to be a clinical way to say: I don't know.

I agree with the statement of Dr. Millard Bass, the forensic pathologist at the State University of New York: "We'll never prevent deaths if we act like ostriches putting our heads in the sand . . . To sign these deaths off as SIDS is unfair to other children whose lives may be endangered by asphyxiation, hyperthermia, and suffocation due to an adult lying on the child: possible causes of death in cases diagnosed as SIDS ."

If the process of investigation is so "unnecessarily traumatiz(ing)" Dr. Mandell, please offer Dr. Bass and others alternate solutions to obtain the true facts. You owe these facts to the parents of the infant victims, and the parents of the infants yet to be. Alan H. Lee Washington Dr. Millard Bass is absolutely correct: U.S. statistics on sudden infant death syndrome are "meaningless" because infant deaths are not being properly categorized.

Dissatisfied Parents Together (DPT) continues to receive reports of pertussis vaccine deaths that are misclassified as SIDS, despite the fact the babies exhibited classic pertussis vaccine reaction symptoms prior to their deaths. A baby who has fever, high-pitched screaming, shock/collapse, or other neurological signs shortly after a DPT shot and is subsequently found dead is not a baby who died from SIDS.

Dr. Samuel Katz, chairman of the immunization practices advisory committee of the Centers for Disease Control, agrees with us. At a May 12 meeting in Atlanta during which our organization reported pertussis vaccine deaths misclassified as SIDS, Dr. Katz promised us that he would work with the Academy of Pathologists and other organizations responsible for educating medical examiners "to look at more appropriate utilization of the term SIDS as an autopsy diagnosis." The Washington Post has pointed out a problem that deserves serious investigation. Barbara Loe Fisher Vienna The Other Side of Animal Research The article by Charlton Heston Second Opinion, July 9 mirrors the erroneous concepts of the general public and the self-serving propaganda of the Association of American Medical Colleges regarding the use of animals in biomedical research.

The development of the smallpox vaccine was indeed a major medical achievement, but one that resulted from the observations of Edward Jenner on humans, and was not dependent on experiments using animals as Heston suggests.

Further, it was not hundreds of thousands of dead monkeys that provided the key innovation leading to the polio vaccine, but rather the development of alternative non-whole animal methods to grow the polio virus in cell culture. The AIDS virus was discovered, and is currently being studied in great detail, by using cell and tissue culture techniques.

The decline in human mortality during the last century is traditionally ascribed to animal-based biomedical research. But the principal factors involved in reducing human risks were improved diet, hygiene and sanitation. Increased survival owed more to the expansion of preventive medicine and public health activities than laboratory animals.

Finally, if pound animals are appropriate or necessary for use in biomedical research, why then is their use banned in four countries, prohibited for all in-house research programs of the National Institutes of Health and strongly advised against by the World Health Organization? In 1969, carefully controlled experiments proved that pound animals are unsuitable and more costly to use in biomedical experiments than purpose-bred animals. That is why less than 1 percent of the animals used in research come from such sources.

Mr. Heston is clearly condoning the continuation of inferior science by endorsing the use of this nation's pets in our research laboratories. John A. Hoyt President Humane Society of the United States Washington It has been proven over and over again that results from tests done on animals cannot be assumed safe when applied to humans. To name a few: After extensive animal testing, a painkiller named Orabilex caused kidney damage with fatal outcome; MEL/29 caused cataracts; Metaqualone caused psychic disturbances leading to at least 366 deaths; Thalidomide caused more than 10,000 deformed children worldwide; Choramphenicol caused leukemia; Stilbestrol caused cancer in young women; and Isoproterenol, an aerosol spray, killed thousands of asthma sufferers in various countries. All of these drugs had been approved and marketed after having proved safe for animals.

Mr. Heston should be made aware that there is no "promise" in animal research. Each species, human and nonhuman, reacts in its own distinct way to drug testing. The platitudes in the article hide the fact that experiments committed upon animals in the name of science are only beneficial to the perpetrators, for they are the recipients of billions of dollars in grants by the U.S. government. Ninie Murray Bowie Correction

The name of K.A. Calis was misspelled Letters, July 16 and his title, Pharm.D. (doctor of pharmacy), inadvertently omitted.