Hyalomma ticks: bovine resistance under field conditions as related to host age and breed.

Field collection of ticks from two breeds of cattle [Native breed (local) and purebred [Friesian)], showed that the number of ticks was higher on purebred than on native cattle. The susceptibility seemed to increase with the age of the animals. Furthermore, breed appeared to exert more influence than age. There was no correlation between the number of ticks associated with each animal, the antibody production and antigens recognized. The immune response under field condition looked more like immune suppression than immune protection.