Survival and infectivity of Babesia in blood maintained at 25 C and 2-4 C.

Babesia microti-infected blood was stored at room temperature (approximately 25 C) or refrigerated (4 C) for 30 days. To assess viability of the parasites after storage at these 2 temperatures, a 0.25-ml aliquot was inoculated into each of 2 hamsters in 2 separate experiments at days 3, 7, 10, 14, 17, 21, 25, and 30. Blood films were prepared and examined weekly for the presence of parasites from all hamsters. Of hamsters inoculated with blood held at room temperature, only those inoculated at day 3 became positive, whereas 4/4 hamsters inoculated with refrigerated blood on day 17 became parasitemic and 1/4 hamsters inoculated with blood held for 21 days became parasitemic. These results indicate that under blood banking conditions, this intracellular protozoan parasite can remain infective and transfusion-acquired infection with this parasite could occur throughout most of the time that blood is normally stored.