Although several cytokines and molecules that play a role in bovine babesiosis, such as IL-1β, IL-12, IL-15, IL-18, TNF-α, IFNα, IFNγ, and NO, have been identified [5,9], until now, there is insufficient evidence for the immune molecular response induced by B. bigemina during the acute phase of the disease or for the gene expression induced by an attenuated B. bigemina strain with immunogenic capacity. Here, IL15 is linked to babesiosis.