Elevated IL-6 levels, as seen in acute KETRI 3801 infection, are associated with highly virulent strains in other infections (Ng et al., 2009; Velazquez-Salinas et al., 2018) and are predictive of disease severity, as reported in bovine trypanosomiasis (Kuriakose et al., 2016). This evidence concerns the gene IL6 and infection.