Necrotic enteritis predisposing factors in broiler chickens

Abstract

Necrotic enteritis in chickens develops as a result of infection with pathogenic strains of Clostridium perfringens and the presence of predisposing factors. Predisposing factors include elements that directly change the physical properties of the gut, either damaging the epithelial surface, inducing mucus production, or changing gut transit times; factors that disrupt the gut microbiota; and factors that alter the immune status of birds. In the past research into necrotic enteritis predisposing factors was directed by the simple hypothesis that low-level colonization of C. perfringens commonly occurred within the gut of healthy chickens and the predisposing factors lead to a proliferation of those bacteria to produce disease. More recently, with an increasing understanding of the major virulence factors of C. perfringens and the application of molecular techniques to define different clades of C. perfringens strains, it has become clear that the C. perfringens isolates commonly found in healthy chickens are generally not strains that have the potential to cause disease. Therefore, we need to re-evaluate hypotheses regarding the development of disease, the origin of disease causing isolates of C. perfringens, and the importance of interactions with other C. perfringens strains and with predisposing factors. Many predisposing factors that affect the physical and immunological characteristics of the gastrointestinal tract may also change the resident microbiota. Research directed towards defining the relative importance of each of these different actions of predisposing factors will improve the understanding of disease pathogenesis and may allow refinement of experiment disease models.

NetB and necrotic enteritis: the hole movable story

“…The isolation of netB-positive strains from healthy birds indicates A c c e p t e d M a n u s c r i p t 6 that simple infection is not sufficient to induce disease. The need for predisposing factors to be present in order for disease to develop is well recognised (Moore, 2016;Shojadoost et al, 2012;Williams, 2005). The common finding that a proportion of C. perfringens strains isolated from diseased birds do not carry the netB gene has sometimes been suggested to indicate that NetB is not an essential virulence factor or that other factors can cause virulence in its absence (Drigo et al, 2009;Martin & Smyth, 2009).…”

Probiotics mitigating subclinical necrotic enteritis (SNE) as potential alternatives to antibiotics in poultry

“…10 6 cfu/g of digesta, in the small intestine of chickens, then birds become prone to NE (Kiu and Hall 2018;Yang et al 2016). There are many predisposing factors, such as viscosity of digesta, the presence of non-digestible polysaccharides, the gastrointestinal tract transit time and the intestinal pH, which are responsible for the ability of bacteria to cause the disease (Moore 2016;Yang et al 2019). One of the important factors is the coccidiosis caused by Eimeria species, which creates a suitable environment for the proliferation of CP (Si et al 2007;Van Waeyenberghe et al 2016).…”

Salmonella-vectored vaccine delivering three Clostridium perfringens antigens protects poultry against necrotic enteritis.

“…It is made available under a The copyright holder for this preprint (which was not this version posted May 9, 2018. . https://doi.org/10.1101/318469 doi: bioRxiv preprint composition, stress, coccidiosis, and immunosuppression due to infection with certain viruses [3]. This disease is estimated to cause annual global losses of up to $6 million dollars to poultry producers.…”