Malaria, while predominantly a concern in tropical regions, poses an increasing threat to the U.S. blood supply due to frequent international travel and climate change factors that could expand mosquito habitats. The FDA notes that approximately 28 million U.S. residents travel to malaria-prevalent regions annually, heightening the risk of introducing the disease into the domestic blood supply.
Historically, malaria was a significant health issue in the U.S., with around 65,000 cases annually until aggressive mosquito control measures during the 1940s largely eradicated the disease domestically. Today, the U.S. sees about 2,000 cases a year, primarily travel-related, according to the Centers for Disease Control and Prevention (CDC). However, the potential for local transmission persists, as evidenced by isolated incidents in states like Texas and Florida.
In March, the FDA approved the Cobas malaria test by Roche, capable of detecting the RNA and DNA of malaria-causing parasites in donor blood, organs, and tissues. This development comes as part of the FDA’s ongoing efforts to ensure the safety of the blood supply, given the potentially severe consequences of malaria transmission through blood transfusions.
Current FDA guidelines require blood banks to use a donor history questionnaire to screen for malaria risk, but these measures are seen as complex and prone to errors. For example, potential donors who have traveled to or lived in malaria-endemic regions within specific time frames are deferred from donating, which can lead to a significant number of healthy donors being turned away—estimated between 50,000 to 160,000 annually.
The FDA is now considering two primary strategies to update its guidelines. The first strategy involves selective testing based on a donor’s history of malaria infection or travel to endemic areas. The second, more comprehensive approach suggests testing all donors at least once and then conducting selective tests for those with a history of malaria or travel to at-risk regions within the last three months.
During a recent advisory committee meeting, most members favored the first option, citing the low incidence of malaria and its treatability as reasons why universal testing might be excessive. However, there was also a proposal to require testing of all donated blood in areas with recent locally transmitted cases of malaria, a suggestion that received mixed reactions due to the complexities involved.
Ralph Vassallo, representing leading blood and biotherapies organizations, advocated for a cautious approach to guideline changes. He suggested that limited testing in areas with known local transmissions could be beneficial, but emphasized the need for formal modeling studies to better understand asymptomatic infection levels before finalizing any new strategies.
The FDA has not yet made a decision but is taking these discussions into account as it considers revising its guidelines to enhance the safety of the blood supply while minimizing unnecessary deferrals of potential donors. This careful consideration aims to maintain the delicate balance between protecting public health and ensuring sufficient blood resources for those in need.
