Preventing transfusion-transmitted infections through improved blood screening methods

Jan 2 2008

The blood transfusion community should consider pathogen inactivation methods as an alternative way to assure the safety and availability of the nation's blood supply, a pathologist wrote in the December issue of the American Journal of Clinical Pathology (AJCP).

"For more than 20 years we have used a method that includes asking potential donors a series of questions to determine whether or not we should use their blood," said Jeffrey McCullough, MD, FASCP, professor of laboratory medicine and pathology at the University of Minnesota.

"But now there are proactive methods available that allow us to use blood that we may not have used if we didn't get a certain answer."

His article, "Pathogen Inactivation: A New Paradigm for Preventing Transfusion-Transmitted Infections," reviews the shortcomings of the current paradigm of blood banking and what is on the horizon with newer pathogen inactivating methods.

The riboflavin method, which works by damaging DNA to eliminate its capability of regenerating, is effective for inactivating intracellular and extracellular HIV, West Nile virus, Staphylococcus, Escherichia coli and several others.

In the amotosalen method, cross-links are created, preventing harmful DNA or RNA from separating and replicating. Amotosalen also inhibits the synthesis of certain proteins, reducing the likelihood of transfusion reactions. Amotosalen treated platelets are now widely used in Europe and the riboflavin method was recently approved there. Amotosalen treated platelets are awaiting action by the U.S. Food and Drug Administration.

Finally, the RBC method cross links DNA and RNA, effectively targeting nucleic acids in pathogens. Further developments are needed to begin a new Phase 3 trial of this method in the United States.

According to the American Red Cross, the safety of the blood supply is maintained by screening potential donors for a variety of risks, including recent infections, recent antibiotic intake, bleeding conditions, fever, sexual practices, and more. McCullough acknowledged that the screening approach, followed by selective testing, has resulted in a very low risk of transfusion-transmitted infection. The chance of contracting HIV through blood transfusion, for instance, is 1 in 1.5 million.

However, said McCullough, if a person has traveled outside of the United States in the past 12 months, they may be prohibited from donating blood. Pathogen inactivation methods, now widely used in Europe, offer several ways to test and treat blood for use.

"We could potentially be turning away a lot of usable blood with the question method," he said. "Someone very well may have traveled, but didn't contract anything."

While the cost of pathogen-inactivation may be an issue, McCullough sees the payoff through elimination of countless hours developing strategies to deal with new agents and the elimination of costs associated with caring for patients with transmitted diseases.

Founded in 1922, the American Society for Clinical Pathology is a professional society with nearly 130,000 member pathologists and laboratory professionals. Based in Chicago, the ASCP provides excellence in education, certification, and advocacy on behalf of patients, pathologists, and laboratory professionals.