Blood transfusions have saved a lot of lives, my own included, but gone are the days when we thought that the chief concern with blood transfusions was transfusion reactions. Units of blood today are subjected to a growing battery of tests to detect infectious agents, because many pathogens are found in the blood stream and can easily be passed from donor to recipient, setting up a new infection. Blood transfusion can pass along HIV, hepatitis, malaria, trypanosomiasis, and a host of other things. Now, Babesia is recognized as being common enough to be of concern for the blood supply.
Babesia is a tiny blood parasite usually transmitted by a tick bite. The tick responsible is the same species that transmits Lyme disease, and babesiosis appears to be following in the footsteps of Lyme, appearing in places where Lyme has emerged, notably the northeastern United States.
[caption id="attachment_290" align="alignleft" width="300" caption="Babesia in ticks, mice, and humans"][/caption]
In some places, studies show, about one in ten people have antibodies to Babesia, indicating that they have been infected. Because the diagnosis is often missed, and because, while fatal in some cases, the infection goes unnoticed in many people, the infection is likely considerably more common that we think.
It looks as though we’ll need to add a screen for Babesia to the processing of blood units for transfusion, at least in places where Lyme disease is common. Though babesiosis is mild in many cases, anyone receiving a blood transfusion is likely more vulnerable to serious illness. Reliable, cost effective, large scale screening methods, however, take time to develop and implement.