 Fine-skinned "Bos taurus" cattle breeds such as Holstein-Friesian and Jersey are the most susceptible to the disease.Thick-skinned "Bos indicus" breeds including the Afrikaner and Afrikaner cross-breeds show less severe signs of the disease.This is probably due to the decreased susceptibility to ectoparasites that "Bos indicus" breeds exhibit relative to "Bos taurus" breeds.