Serum IL-10 seems a potential marker for intestinal pathology, notably relating to Eimeria infection, but strategies that seek to upregulate immunoregulatory or anti-inflammatory, or downregulate proinflammatory, mediators, particularly in the very early phase of infection, maybe ill-founded, particularly given the majority of important poultry pathogens are intracellular. This evidence concerns the gene IL10 and infection.