Health & Medicine / Infectious Diseases
Top 100 Stories of 2011 #27: Babesia Parasite Taints the Blood Supply?
Blood transfusions have infected 159 patients with the malaria-like parasite.
by Linda Marsa From the January-February special issue; published online January 5, 2012

A report released earlier this year confirmed something that has increasingly concerned public health authorities over the past decade or so: In the last 30 years, blood transfusions caused at least 159 cases of babesiosis, an emerging infectious disease that is normally transmitted by ticks. And the risk may be increasing because the majority of these incidents—77 percent—occurred between 2000 and 2009. Twenty-eight of the patients died soon after their transfusions, and in many cases, the infection may have contributed.
Babesia, a malaria-like parasite that infects red blood cells, “has become the most frequently reported infectious agent transmitted by blood transfusions in the U.S.,” says Barbara Herwaldt, a medical epidemiologist at the Centers for Disease Control and Prevention who was lead author on the report. And these numbers may represent a small fraction of the actual cases, because babesiosis is often missed or misdiagnosed as malaria or flu.
Once known as Nantucket fever because some of the first cases were reported on the Massachusetts island, Babesia can cause such flulike symptoms as fever, headaches, chills, and drenching sweats. It can be treated with antibiotics. But the tickborne disease can become quite serious or even fatal for patients with weak immune systems—like neonates and infants, the elderly, or people without a spleen—causing anemia, organ failure, and death.