Although the risk of getting AIDS from blood transfusions has diminished, a major study of heart surgery patients has found that two were infected with the AIDS virus through blood transfusions from donors who slipped through screening tests since 1985.
The study of 11,535 patients at three hospitals traced the infected blood to two donors who tested negative for human immunodeficiency virus, or HIV, at the time of donation but later tested positive, said Dr. Kenrad E. Nelson, an epidemiologist at the Johns Hopkins School of Hygiene and Public Health.
The reason blood banks cannot completely eliminate the risk of acquired immune deficiency syndrome spread through blood transfusion is a two- to six-month "window" between the time a person is infected with the virus and the time a blood test will detect antibodies to the virus, Dr. Nelson said.
He gave a report on the study conducted at Hopkins and at hospitals in Houston and Chicago to the American Association of Blood Banks during its annual meeting in Baltimore this week.
The risk of getting AIDS through transfused blood or blood products is about 1 in 60,000, Dr. Nelson said. But a Gallup poll released yesterday shows that public perception of the risk is much greater than the reality.
Slightly more than half of the American public -- 52 percent -- believe it is "likely" they could get the AIDS virus from a blood transfusion, according to a random, nationwide telephone poll of 1,000 adults in July and August.
Asked their greatest concern if they had to have an operation, almost as many people (26 percent) cited the risk of getting AIDS from a blood transfusion as did those citing complications due to errors by the surgical team (29 percent).
And contracting AIDS was found to be a greater concern than was failure of surgery to solve the problem or complications that could oc cur from anesthesia.
For the third consecutive year, AIDS topped the list of diseases that respondents saw as the most serious health problems facing the United States: 27 percent cited AIDS; 20 percent, cancer; and 10 percent, heart disease.
Despite their concern about AIDS, nearly three-quarters of respondents felt the blood supply from volunteer donors to be "somewhat safe" to "very safe." The number answering "very safe" has been declining over the last five years.
And 62 percent said they believe the blood supply to be safer today than five years ago.
Donald D. Doddridge, president of the American Association of Blood Banks, which released the poll, yesterday conceded the widespread misperception about the risk of getting AIDS through blood transfusions.
"We do think the public still needs to be educated about the risk," he said.
However, he added, blood banks are not planning to do any more than they already do to educate communities in their areas.
Since 1985, only 20 people out of 20 million who received blood were infected with the AIDS virus by contaminated blood, Mr. Doddridge said. Also, tests are being refined, he said, so that the "window" of time between infection and showing positive for the virus has narrowed.
Latest statistics from the Centers for Disease Control show that from 1981 through September 1991, 2 percent of infected adults and 9 percent of children (not counting hemophiliacs) got AIDS through transfusions of blood or blood products.