Transfusion Medicine
Young patients who face years of transfusions should be started on iron chelation to avoid iron overload. For older patients with transfusion-dependent anemia, iron chelation therapy should be considered if their life expectancy is long (years to decades) or special studies such as T2-weighted cardiac magnetic resonance imaging showing iron overloading.35
INFECTIOUS COMPLICATIONS
Concern over transmission of HIV infection via blood products in the late 1980s led to both a reduction in blood product use and a greater awareness of infectious complications of transfusion and their prevention. However, no blood product can ever be assumed to be safe for 2 reasons. One is that blood products can transmit infections during a “window period”—the time before a contaminated product can be detected by testing. The second is that blood is not screened for all potential infections (eg, babesiosis or new infections such as West Nile virus at the start of the outbreak). Risk of infection is reduced in 2 ways: deferral of potential infectious donors and blood product testing.
As part of the donation process, potential blood donors are asked a series of questions to see if they have risk factors for infections (eg, recent travel to malarious areas, recent tattoos), and if they answer positive are deferred from donating blood. Blood products are then tested for infectious agents by a combination of methods including detection of viral antigen, antibody response to infections, and more recently polymerase chain reaction (PCR).36 Current screening includes syphilis testing; testing for antibodies to HIV, HTLV (human T-lymphotropic virus), hepatitis C virus, hepatitis B core antigen (HBcAg), hepatitis B surface antigen, and PCR for HIV, hepatitis B virus, HCV, and West Nile virus. Some centers also test for Trypanosoma cruzi, the cause of Chagas disease.
In the past, the numerically most common transfusion-related disease was hepatitis, first B and then C.37,38 The first step in eliminating these infections was to stop paying donors for blood products. With the introduction of effective testing for hepatitis B and then C, the incidence of transfusion-related hepatitis has plummeted.36 For example, with the introduction of a diagnostic test for hepatitis C, the estimated risk has fallen from 5% to less than 1 per million. Currently, the risk of transmission of hepatitis B and C, HIV, and HTLV is less than 1 in a million.38
Despite this testing, blood transfusions can transmit a variety of infections, including malaria and babesiosis.39 Any new blood-borne infection introduced into the population can get into the blood supply as well. For example, at the start of the West Nile virus epidemic, there was a cluster of transfusion-transmitted cases that resulted in severe and sometimes fatal illness in immunosuppressed patients, but this issue has been addressed with the development of a PCR assay for screening blood.40 The rate of transfusion-related babesiosis has been increasing and screening for the causative parasite is being considered.
