Several studies show elevated serum levels of cytokines such as IL-4, IL-6, IL-12, IFN-γ and TNF-α during the active phase of the disease compared to asymptomatic infection (Peruhype-Magalhães et al., 2005; Peruhype-Magalhães et al., 2006; Costa et al., 2012). The gene discussed is TNF; the disease is infection.