A careful analysis of the systemic (serum) cytokine levels in mice chronically infected with the Omani isolate revealed that type 1 (IFN-γ, TNF-α, GM-CSF), type 2 (IL-5, IL-13, to a lesser degree IL-4), and type 17 (IL-17) cytokines coexisted throughout the infection. This evidence concerns the gene IL4 and infection.