TNF and infection: Experimental infection of pigeons with E. labbeana-like oocysts resulted in peak fecal oocyst shedding (~5.25 × 105 oocysts/g.feces), extensive development of intracellular parasite stages (meronts, gamonts, and developing oocysts), a marked reduction in goblet cell numbers, and elevated intestinal inflammatory responses, including increased NF-κB and IFN-γ immunoreactivity, as well as upregulated mRNA expression of IL-1β, IL-10, IFN-γ, and TNF-α.