Veterinary Parasitology, 37 ( 1990) 301-306 301 Elsevier Science Publishers B.V., Amsterdam Short Communication Post-thawing viability of vaccines for bovine babesiosis and anaplasmosis cryopreserved with glycerol A.J. Mangold, D.H. Aguirre and A.A. Guglielmone* Grupo de Estudio en Sanidad Animal, Instituto Nacional de Tecnologia Agropecuaria, 6\ C. 228, 4400 Salta (Argentina) (Accepted for publication 16 May 1990) ABSTRACT Mangold, A.J., Aguirre, D.H. and Guglielmone, A.A., 1990. Post-thawing viability of vaccines for bovine babesiosis and anaplasmosis cryopreserved with glycerol. Vet. Parasitol., 37:301-306. Live frozen vaccines containing Babesia bovis, Babesia bigemina or Anaplasma centrale were pre- pared using glycerol as cryoprotectant and stored in liquid nitrogen. The viability of the vaccines was tested inoculating calves 1 h (n=12), 2 h (n=12), 12 h (n=6) and 24 h (n=6) after thawing. Babesia bovis and A. centrale were detected in thin and/or thick blood smears in all vaccinated calves; however, 1 of 12 calves inoculated 1 h after thawing and 3 of 6 calves inoculated 24 h after thawing did not develop a B. bigemina parasitaemia. The longer post-thawing durability of frozen vaccines cryoprotected with glycerol compared with those cryoprotected with dimethyl sulfoxide, presented by other authors, will extend their use under field conditions. INTRODUCTION Frozen live vaccines for cattle babesiosis and anaplasmosis are a safer product than refrigerated vaccine. They can be stored for long periods of time allowing exhaustive testing of the batches before their release onto the market (Pipano et al., 1986). Both refrigerated and frozen vaccines contain bovine red blood cells parasitized with Babesia or Anaplasma. Glycerol has been con- sidered less efficient than dimethyl sulfoxide (DMSO) to cryopreserve these haemoparasites because of its slow permeation into the bovine erythrocytes (Lovelock and Bishop, 1959; Dalgliesh, 1972). However, the post-thawing lifespan of frozen vaccines for anaplasmosis containing DMSO is very short; they must be applied within 30 min after thawing (Pipano et al., 1986; Gug- *Author to whom correspondence should be addressed. 0304-4017/90/$03.50 © 1990 -- Elsevier Science Publishers B.V.