Correlation of serum zinc levels with resistance of cattle to trypanosomiasis.

Zinc, copper and magnesium levels were determined by atomic absorption spectrophotometry in the serum of 32 cattle (Zebus and Baoulés) which were proven to be sensitive to African trypanosomiasis under field challenge and 45 cattle (Baoulés and Ndamas/Baoulés) which were proven to be resistant. Copper and magnesium levels were similar in all animals but zinc levels were higher in sensitive animals (1.50 ppm) than in resistant ones (1.10 ppm) (p less than 10(-5)); the reported normal levels of serum zinc is 1.00 ppm. These differences persisted on repeated measurements and whether individuals were infected with trypanosomes or not. Elevated levels of zinc depressed the stimulation of bovine T cells by trypanosomes in vitro and is reported to inhibit antigen presentation by macrophages. Zinc levels may be an influencial factor determining susceptibility or resistance of West African cattle to trypanosomiasis.