LONDON -- Hundreds of people are dying each year from a blood transfusion problem that could be prevented, Reuters quoted **** New Scientist **** magazine as saying on Wednesday.

Transmission-related acute lung injury (TRALI) occurs when people have an adverse immune reaction triggered by antibodies in donor blood.

TRALI, which scientists suspect is caused by donor blood from people who have been exposed to a variety of blood groups, causes a mild reaction in most people and is generally thought to result in only a handful of deaths.

But a California blood bank, Bloodsource, estimates that TRALI occurs in one in 5,000 transfusions each year in the United States alone and causes about 500 deaths.

"That makes it a bigger problem for blood banks than high-profile diseases like HIV," the magazine said, referring to the virus that causes AIDS.

Shortness of breath is the first symptom but it can also be a normal reaction when blood is transfused too quickly. Blood pressure readings can distinguish TRALI from a normal reaction because people with the problem have low pressure, according to the magazine.

One way to prevent TRALI would be to screen high-risk donors exposed to multiple blood groups such as people who have had several transfusions or women who have had three or more children. But researchers believe it would do more harm than good because of the shortage of blood donors.

Another option would be to carry out costly tests to screen for blood products that contain high amounts of plasma from high risk donors.

The U.S. Food and Drug Administration (FDA) is calling for more research into TRALI and the problem will also be discussed at the annual meeting of the American Association of Blood Banks at their annual meeting next month, the magazine added.