Summary of predisposing factors for necrotic enteritis development in chickens. Predisposing factors and the major effects of these factors are shown in ovals. Important factors that may drive the influence of the predisposing factors are shown in the small rectangular boxes. Abbreviations: CIA, chicken infectious anemia; Cp, Clostridium perfringens; IBD, infectious bursal disease; MD, Marek's disease; NSPs, nonstarch polysaccharides (Moore, 2016).