Infectivity of cryopreserved Babesia bovis, Babesia bigemina and Anaplasma centrale for cattle after thawing, dilution and incubation at 30 degrees C.

Blood containing either Babesia bovis, Babesia bigemina or Anaplasma centrale was mixed with an equal volume of 3 M glycerol in phosphate-buffered saline with or without glucose and then stored in liquid nitrogen for 2-30 days. After being thawed, the parasitized blood was subjected to various procedures, including dilution up to 1000-fold followed by incubation at 30 or 4 degrees C for 8 h, before infectivity of the parasites was tested in a total of 70 cattle. The results showed that the blood cryopreserved with glycerol remained highly infective after thawing, despite dilution and incubation for 8 h at 30 degrees C. The results have practical application in the use of frozen, live vaccines against bovine babesiosis and anaplasmosis.