BOSTON — It's an infection transmitted by ticks that may not make you sick but could kill someone who gets your donated blood.
It's called babesiosis and the Food and Drug Administration just came out with strict new recommendations on screening for the parasite causing the disease.
Type O blood is in critically short supply this first holiday weekend of the summer.
"It's the kind of blood that's most in demand from hospitals and emergency rooms and trauma situations," American Red Cross spokesperson Kelly Isenor said. "Right now, only three in every hundred people in the United States donate blood and that number just isn't enough to keep up with the needs of hospital patients."
With the Red Cross down to a two-day supply from its normal five.
Medical screening has always been part of the blood donation process, but this month a new recommendation from the FDA includes wholesale testing of donor samples in certain areas of the country for the tick-borne infection babesiosis.
"I've seen people get very sick from this and it's great to avoid that," Doctor Steven Sloan said. "So I think it's an excellent move on the FDA's part."
Sloan is the medical director of the blood bank at Boston Children's Hospital, where they've been testing blood donations for babesia the past few years -- with good reason.
"It is the disease that has caused the most transfusion-transmitted fatalities in the U.S. over the last decade," Dr. Sloan explained.
The FDA report notes that of the 200 known cases of babesiosis from blood transfusions, 95 percent came from fourteen states and the District of Columbia. Those states include all six in New England.
The report recommends updating health questionnaires in the most-affected states.
"So if a sample tests positive, the first thing is we do not use that blood for any patients. That blood will be discarded," Sloan said.
Donors testing positive would be deferred from further donation for two years.
Although the FDA report makes clear that it is recommending babesia testing -- not requiring it -- Sloan predicts every blood supplier will get on board in time.
"So, [it will] probably be another year before most places will be testing for Babesia in this part of the country," Sloan said.
And yes, that could mean more cases of transfusion-caused babesiosis.
But Sloan says with one positive in every few thousand donations, the risk is still small.
Boston Children's Hospital says it is in dire need of blood donations. You can find out how to help here.