The virus that causes acquired immune deficiency syndrome (AIDS) can remain in a person's body for five years or more without causing the disease, but the carrier can still be infectious to others, researchers from the Centers for Disease Control warned yesterday.
Dr. Paul M. Feorino said new studies, which involved blood donors who inadvertently passed on AIDS through transfusions, strongly support the new nationwide program to screen donated blood for signs of the AIDS virus.
Meanwhile, the American Red Cross, which has been screening blood since early March with a new test, has decided it will notify donors when it finds that their blood contains the virus.
Dr. S. Gerald Sandler, the Red Cross associate vice president for medical affairs, said that beginning July 1, the agency will discard all blood that the test indicates contains the AIDS virus, but that donors will be notified only when a second test confirms that antibodies to the AIDS virus are present. The presence of antibodies suggests that a person has been infected in the past, but does not indicate whether the person will contract the disease.
Sandler said the policy seeks to protect "transfusion recipients from the possibility that a unit of blood might be infected. On the other hand, donors must be protected from notification of a positive test unless that test has been confirmed to be a true positive test." There is concern about the possibility of "false-positive" results from the screening test alone, he said.
Preliminary Red Cross studies show that about two units of blood per 1,000 are being withdrawn after being tested. Sandler estimated that about 25 percent of donors whose blood has been rejected will be notified in the initial phase of the program.
The agency will advise those people to seek a medical evaluation and their names will be kept on a confidential, national "deferral" registry, he said.
But if the positive results are not confirmed and there is no notification, the information will still be kept in a confidential file at the local blood bank, Sandler said.
Should such a person donate again, his or her blood would not be tranfused and would be "carefully evaluated."
From 1981 through May 13, the CDC reported 10,226 victims of AIDS in the United States, about half of whom have died. The cases of 138 adults -- about 1 percent of adult cases -- and 17 children -- about 14 percent of pediatric cases -- are thought to have been caused by blood transfusions.
The new CDC study, reported in the New England Journal of Medicine, investigated 25 male donors thought to be at high risk of AIDS who were later linked with transfusion-associated cases of the disease. High-risk cases, who are now urged not to donate blood, include homosexual men, intravenous drug abusers and their sexual contacts.
The published study said that samples of the AIDS virus were recovered from 22 of the 25 donors between 12 and 52 months after they had donated blood, with a midpoint of 28 months. Feorino said that more recent studies had recovered virus "close to 6 years" after blood donations, suggesting that the virus may remain hidden in the blood indefinitely in some cases.
Of the 22, two-thirds -- 15 donors -- remained free of AIDS symptoms, five had symptoms of an illness that sometimes precedes AIDS, while two had been diagnosed with AIDS. All of the donors with virus in their blood also tested positive.
There is no cure for AIDS, but a number of drugs are under study. A California company, Newport Pharmaceuticals, said yesterday that it is hopeful that it can work out a plan, with Food and Drug Administration approval, for distributing a highly experimental drug called isoprinosine to AIDS patients who do not respond to other treatment.