Chicago Tribune (CT) - Sunday, June 9, 1985, Page: 1
Ronald Kotulak, Science writer

The chance of developing Acquired Immune Deficiency Syndrome from transfusions has dropped from 1 in 100,000 to 1 in 4 million because of the new blood-screening test, said Dr. Richard Decker, a spokesman for Abbott Laboratories, the first company to market the test.

The test has defused one of the worst dangers to threaten the nation's blood supply, said Gene Jeffers, of the Red Cross in Washington. "By solving this problem as quickly as we did we were able to eliminate a large part of the fear of getting AIDS from blood transfusions," he said.

The test also may have snuffed out unwarranted fears that giving blood could expose a person to AIDS, he said. Such concerns have created serious blood shortages in San Francisco and smaller declines in donations elsewhere.

A growing number of people were having their own blood stored before they had elective surgery so it could be used if they needed a transfusion, he added. Others have said they would take only blood donated by relatives or friends.

The test, which detects antibodies to the virus linked to AIDS, is being used at all Red Cross blood banks, Jeffers said. The Red Cross collects about 6 million pints of blood annually, half of all the blood collected in the United States, he added.

About 95 percent of all blood being collected at Red Cross centers and other blood banks now is tested for antibodies to the HTLV-III virus, the organism thought to cause the syndrome, said Decker, Abbott's manager of experimental biology.

Because of the test, which was approved by the federal Food and Drug Administration in March, the Red Cross is destroying 2.3 to 2.7 pints of blood for every 1,000 units collected because they may be contaminated with the AIDS virus.

An estimated 3 million Americans receive blood transfusions each year. "If we had not begun testing as soon as we did, the blood supply would not be as safe as it is today," Jeffers said.

As of May 10, 149 Americans, including 15 children, have developed AIDS after receiving transfusions of blood that contained the AIDS virus.

How many more people will develop AIDS from blood they received before the mass screening started is not known, Jeffers said. The incubation period of the virus may be as long as five years.

The test, which takes three hours to perform, will add $24 million to $36 million a year to the nation's blood banking bill, but "that's cheap insurance," Jeffers said.

AIDS, which destroys a victim's immune defense system, was first recognized in 1981. The HTLV-III virus that is thought to cause the deadly disease was discovered by American and French scientists last year.

The AIDS epidemic has grown out of control, according to health experts. More than 10,000 people have contracted the disease and about half of them have died. There is no effective treatment for the disease, which is doubling its number of victims every year.

Those at highest risk of acquiring AIDS are homosexuals, bisexuals and abusers of drugs taken intravenously. Also at risk are hemophiliacs who use blood products and people who receive transfusions of contaminated blood.

Public health officials fear the disease is spreading to the heterosexual population, primarily through sexual intercourse, and officials of the federal Centers for Disease Control estimate that 1 million Americans may have been exposed to the AIDS virus.

The Abbott test is considered to be 98 percent accurate in detecting AIDS antibodies in blood, but it will produce a positive result in many cases when AIDS antibodies are not present.

"The test is overly sensitive, but we wanted it that way to make sure that the chance of any AIDS virus sneaking by was as small as possible," Jeffers said.

Each unit of blood collected is subjected to the Abbott test, he said. If it shows a positive result, it is pulled out of the system and tested twice. If either of those tests comes up positive, the blood is destroyed. If neither of the follow-up tests is positive, then the first test is judged to be a false positive and the blood is considered safe, he said.

A sample of each unit of blood found positive on two or more tests is sent to Abbott in North Chicago, where it is subjected to the Western Blot test for verification. The Western Blot is a different type of AIDS test that is not used for screening because it is too time-consuming and costly.

Of the samples that have been re-tested with the Western Blot, more than 50 percent have been found to be not really contaminated with the AIDS virus, Decker said. Other viruses and human error can make the test produce this result, he explained.

After eliminating these false positives, about 1 out of every 1,000 pints of blood collected is found to be contaminated with the AIDS virus and removed from the system, he said.

Jeffers said that though the Abbott test is 98 percent accurate, it may miss AIDS-infected blood in which antibodies are not present. Antibodies are produced by the body's immune defense system to fight specific viruses.

A person recently infected with the virus may donate blood before his body begins producing AIDS antibodies, Jeffers said, and the bodies of others with AIDS may no longer be making the antibodies. A third group is people who carry the virus but never react to it, so their blood contains no AIDS antibodies.

Health officials have agonized over whether people should be told they have positive AIDS antibody results because of the potential psychological and social harm that may be caused by results that turn out to be false positives.

The trend is to tell donors. The Red Cross recommends that blood banks notify donors when both the Abbott and Western Blot tests are positive.

"The test cannot be used to diagnose AIDS at this point," Jeffers said. "It is used as a blood-screening tool. Positive results from both tests do not mean a person has AIDS or will get AIDS, but it does suggest that he should be checked out by a doctor."

In Illinois, where the rate of positive test results is about half the national average, the Department of Public Health prohibits blood banks from informing donors of positive results. But the policy is under review and may be changed, said Dr. John Francis, chief of the department's division of disease control.

When blood is found to be positive, the donor's name is put on a permanent deferral list so that if he donates blood again, it is not used, said Karen Horist of the Red Cross office in Chicago. All information is confidential, she added.

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