Figure 1 summarizes how predisposing factors cause NE in broiler chickens. Recent studies reported that the Net B-toxin can be detected in the type G strain and has a modest propensity to induce NE, regardless of the presence of predisposing factors such as coccidiosis, high-protein diet, and others that can change gut environments [22]. The type G strain of the Net B-toxin even determines the virulence of CP and promotes the severity of NE when CP and coccidia infections coexist [23]. The gene discussed is CP; the disease is coccidiosis.