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CDC Reports Transmission of Babesia in Blood Transfusions

September 1, 2011

Last week, the Centers for Disease Control and Prevention (CDC) reported that Babesia, a tickborne parasite of red blood cells, is being transmitted through blood transfusions.

The findings were based on data it collected during the past 31 years. Cases were first reported in 1979 and have been on the rise in the past decade. The lead author of the article was Barbara Herwaldt, MD, MPH, a medical epidemiologist with the CDC.

In the US, two species of Babesia are carried by deer ticks. Symptoms of babesiosis, which appear one to four weeks after infection, can be mild to severe. They include head and muscle aches, chills and fever, sweating, nausea and vomiting. Severe complications, such as kidney and liver failure and heart and lung problems, can occur in people without a spleen, infants and seniors, and those with weakened immune systems.

Herwaldt and fellow investigators described 159 transfusion–related babesiosis cases that occurred from 1979–2009; 77% were reported from 2000 to 2009. Because babesiosis cases were not required to be reported to local health departments until January 2011, it is unclear whether the increase in the past decade is related to better diagnosis and reporting or to greater prevalence of the disease. The majority of cases were associated with red blood cell components; four were linked to whole blood–derived platelets. Although cases have been reported in 19 states, most occurred in seven states--Connecticut, Massachusetts, Minnesota, New Jersey, New York, Rhode Island and Wisconsin.

“We want clinicians to become more aware of babesiosis, including the small possibility of transmission via blood transfusion,” said Herwaldt. “If a patient develops unexplained fever or hemolytic anemia after a transfusion, babesiosis should be considered as a possible cause, regardless of the season or U.S. region.” 

Currently, there is no Babesia test approved by the Food and Drug Administration (FDA) to screen prospective blood donors, who can be infected but not know it because they are asymptomatic. However, manufacturers are working with investigators to develop a screening test. 

The study, “Transfusion-Associated Babesiosis in the United States: A Description of Cases,” was published online on September 6, 2011, in the Annals of Internal Medicine.


Source: CDC press release dated September 6, 2011