Cappy Young had a doting wife of 22 years, three daughters, a grandchild, a job he likes and a big house with a two-car garage. And he was feeling better than ever after a doctor operated on him to improve the blood circulation in his legs last March.

He still has all that, yet nothing really will be the same. Last month, Young learned from his Richmond surgeon that one of the six pints of red blood cells transfused into him during the surgery was tainted with the AIDS virus.

Young said a test confirmed that he is HIV-positive, making him one of 20 to 50 Americans each year who contract the AIDS virus through blood transfusions, despite screening protocols that have made the U.S. blood supply the safest it has ever been.

"I went into the hospital to have an operation to relieve one disease that was curable and came out of the hospital with a disease that is not curable and that I can pass on to my wife," Young said yesterday. "The infectious disease control doctor just told me it was my bad luck. I was already upset; I was crying."

Federal blood safety officials arrived at Richmond-based Virginia Blood Services yesterday to check on whether proper procedures were followed when the agency collected the tainted unit of blood from a Richmond donor, screened it and sent it to Virginia Commonwealth University's Medical College of Virginia Hospitals.

The unidentified donor later discovered that he or she is HIV-positive and notified the agency, which alerted the 900-bed hospital.

Raymond Makhoul, Young's vascular surgeon, did not return a call for comment yesterday, but hospital spokeswoman Cari Brunelle said there never has been a similar case of a tainted blood transfusion at her institutions. State health officials said they know of one other case of a Virginia patient contracting HIV from a blood transfusion, a 1986 case that progressed to full-blown AIDS.

Young, 53, is a forklift operator from Petersburg, Va. In the six weeks since he learned he is HIV-positive, he has had to cope with an $800-a-month drug regimen of so-called AIDS cocktails that make him throw up, feel tired and break out in rashes. He worries about the risk of infecting his wife, who so far has tested negative.

He has discovered the limits of social services available to HIV-positive patients in rural areas and smaller cities. He has had to reassure his daughters that he'll be all right and that the doctors tell him he can live a full lifespan if he takes care of himself.

"They say I can live a long, healthy, normal life, but it's not normal, it's not healthy if you have to worry about catching a cold and going into pneumonia quicker than anybody else," he said. "It's not normal to get rare cancers that your body can usually fight off. But I'm going to do what I have to do. I'm a strong person. I'm a fighter."

One of every 680,000 donated units of blood may transmit HIV, according to federal estimates. The Centers for Disease Control and Prevention has counted 39 cases of transfusion-caused AIDS since 1985, but it has no count of how many people today are living with HIV because of transfusions.

Comprehensive testing of donated blood began in 1985 after HIV first contaminated the national blood supply and caused thousands of AIDS deaths in the early stages of the epidemic in the 1980s. That experience, and cases like Young's, have made the stewards of the nation's blood supply militant in barring growing numbers of high-risk groups from becoming blood donors.

In recent years, technology has advanced to the point that the vast majority of contaminated donations can be weeded out through routine blood screening. But tainted blood still sneaks through. The screening tests search for antibodies that develop in the blood after exposure to the AIDS virus.

But antibodies do not appear for about 22 days after infection occurs. That means donors infected less than three weeks before they give blood can pass along the undetected virus. Since 1996, blood collection agencies have been screening for HIV antigens, which appear in the blood about 16 days after infection.

Scientists are working on tests that can close that window of opportunity to less than a week.

"We have always tried to be clear and honest with the public that although the risk of HIV from blood transfusion is very low, it is not zero and remains important," said Jay Epstein, the Food and Drug Administration's director of blood research.

"But I think potential blood recipients, while they should be informed of the risks of transfusion, should understand that for medical conditions where transfusions are needed, the risks of not being transfused far outweigh the risks of being transfused," he said.