Immune response of lambs experimentally infected with Haemonchus contortus and parenterally treated with a combination of zinc and copper

• Haemonchus contortus causes high economic losses and high mortality.
• Mineral enhancing immunity of experimentally infected sheep.
• Evaluation of immunological parameters.

Haemonchus contortus parasite causes high mortality rates and drastic productivity reduction besides enhancing treatment costs. It has also been demonstrating great resistance against most of the drugs currently in use. Thus, the utilization of elements that can boost the host immune response to cope with the infection has been widely studied. Some researchers have shown that the use of zinc (Zn) and copper (Cu) as nutritional supplements can help controlling the parasites. The present study evaluated the immune response of lambs experimentally infected with H. contortus and treated with Zn and Cu. Twenty-one (21) lambs were divided into three groups: CG (non-infected control group), IG (infected group – infection performed with 15,000 larvae of H. contortus/animal) and ITG (group infected and treated subcutaneously with 1.5 mg/kg of Zn and 0.45 mg/kg of Cu on days 10 and 45 post-infection [PI]). Blood samples were drawn on days 0, 14, 28, 42, 56 and 70 PI in order to determine the serum concentrations of interleukin 1 (IL-1), interleukin 4 (IL-4) and interleukin 6 (IL-6), interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) and immunoglobulins (Igs) IgA, IgE, IgG and IgM. The parasitic infection was monitored by the counting of eggs per gram of feces (EPG) in the same intervals of blood sampling. At the end of the experiment, animals were euthanatized and the parasite load was quantified. In addition, the concentrations of Zn and Cu in liver were assessed. A significant increase in EPG was observed only on day 14 PI for IG and ITG (P < 0.05). Between days 14 and 42 there was a significant increase (P < 0.001) of cytokine and immunoglobulin levels in IG and ITG, when compared with the animals of CG. After day 56, the IG animals showed serum level of interleukins and immunoglobulins lower than ITG animals (P < 0.001). Regarding the liver concentrations of Zn and Cu, the infection showed to lead a depletion of these minerals; therefore, the supplementation did not prevent this effect. The results of this study indicate that the administration of Zn and Cu was capable of enhancing the immune response in lambs experimentally infected with H. contortus. However, it did not reduce egg counts in the feces or the number of adult parasites in the abomasum.