Necrotic Enteritis: a devastating disease caused by C. perfringens

What is Necrotic enteritis (NE)?

Necrotic enteritis (NE) is a type of gastrointestinal condition called enterotoxemia caused by the bacteria Clostridium perfringens. NE has a single causative agent and thus is a much simpler disease than bacterial enteritis (BE), which it is commonly confused with. Although many of the contributary factors the same (coccidiosis, feed quality and general intestinal stressors) the disease is quite different and less complex than BE. 

C. perfringens can infect many species and cause differing types of enterotoxemias in sheep, goats, cattle, pig and chickens among others. C. perfringens is a gram positive, spore-forming, rod shaped bacteria. It is found nearly everywhere in an animals environment, usually present in the feed, bedding, faeces, dust and is typically a commensal bacteria in chickens and turkeys. Therefore it is a very difficult bacteria to remove from the environment and animals, unless they are raised from SPF eggs (in the case of chickens) and then brought up in a contained facility with good biosecurity. Whilst this is an option, it is not realistic for the large majority of animal keepers. 

Considering C. perfringens is omnipresent, NE happens relatively rarely, due to the other risk factors required for its emergence. NE is only caused by Necrotic Enteritis Beta toxin (NetB)-producing strains, in combination with a change in the intestinal mucosa due to coccidiosis, worms, mycotoxicosis, infection with other bacteria. Therefore the disease is multifactorial and cannot emerge without the presence of the relevant bacteria and a cause for change in the gut microbiota. NetB toxins cause severe damage to the small intestine and liver, often ending in mortality. A single clone virulent NetB producing strain will outcompete other commensal Clostridia in the gut, and cause severe necrosis by targeting tight junctions between cells. 

What are the clinical signs of NE?

  • The disease can be acute or chronic
  • Intestinal necrosis, inflammation and haemorrhage
  • Liver lesions (cholangiohepatitis)
  • Sudden increase in mortality within the flock
  • Depression
  • Ruffled feathers
  • Diarrhoea
  • “Turkish towel” appearing mucosal intestinal membrane
  • Foul smelling intestinal fluid 

How do I diagnose NE?

There are a few options to detect a C. perfringens infection:

  • Post mortem assessing gross lesions in small intestine; care taken not to be confused with coccidiosis lesions
  • Gram stained smear to determine gram positive rods present
  • Isolation of large numbers of C. perfringens and culture with differential media.

Of course, usually with NE the disease is acute and serious and therefore necropsies may be the route of choice, by an experienced vet. 

How can I get prevent and treat NE?

You can reduce the risk of coccidiosis by giving feed containing anticoccidials and vaccinating your animals. You can also minimise any changes to the gut flora or any stress to the gut by avoiding radical changes to the diet, ensuring amounts of cereals containing non-starch polysaccharides (NSP) like wheat, barley, or rye and fishmeal in the diet are low ( not applicable to all animals). Furthermore the use of pre and probiotics for healthy maintenance of the gut flora and reducing the change of NetB+ C perfringens outcompeting other commensals. 

There are a range of antibiotics licensed for C perfringens but ensure these are used correctly due to the ever increasing pressure of antibiotic resistance.

References

VetWorks Poultry Gut Health Training Belgium Sep 2018

https://www.msdvetmanual.com/poultry/necrotic-enteritis/overview-of-necrotic-enteritis-in-poultry

Shojadoost, B., Vince, A.R. & Prescott, J.F. The successful experimental induction of necrotic enteritis in chickens by Clostridium perfringens: a critical review. Vet Res 43, 74 (2012). https://doi.org/10.1186/1297-9716-43-74