Necrotic Enteritis arises from the excessive proliferation of Clostridium perfringens type A, a foodborne pathogen, and to a lesser extent type C, within the small intestine. The toxins released by these strains of Clostridium perfringens inflict harm upon the intestinal lining. Originally identified in chickens in England in 1961, Necrotic Enteritis can affect around 40% of commercial broiler flocks and can also affect layers and turkeys.
Cause
Necrotic Enteritis is an Opportunistic infection (infections that occur often or more severe in mammals with a weakened immune system). It can be promoted by anything that slows the passage rate of feed in the small intestine or has excessive bacterial growth and toxin production.
Transmission
Clostridium perfringens is usually present in the faeces of some chickens. The litter pecking behaviour of birds causes the organism to spread throughout the flock. The disease affects broiler chickens aged 2 to 5 weeks old and turkeys at 7 to 12 weeks old raised on litter. The organism can also be transmitted through soil, dust and litter.
Clinical signs
The noticeable sign of Necrotic Enteritis in a flock is a sudden increase in mortality (death). Birds that have diarrhoea, depression or ruffled feathers may show signs of infection. The small intestine may be ballooned and easily crumbled. This can cause brown fluid which presents a revolting smell.
The inner lining of organs is covered with a tan or yellow false membrane which progresses to appear as an infection.
The disease can persist in a flock for 5 to 14 days. The mortality rate ranges between 2 to 50%.
Diagnosis
A presumptuous diagnosis of the infection would be examining signs of diarrhoea and depression in poultry. A confirmed diagnosis would be based on gross lesions in the small intestine. Gram- positive rods (bacteria that give a positive result in a Gram-stain test) would also be observed under a microscope. This is done by taking Gram – stained smear of mucosal scraping.
If Clostridium perfringens from intestinal contents that produce the double zone of hemolysis, then it can confirm Necrotic Enteritis. However, this should not be the sole criterion to confirm the infection.
Treatment and control
There are several methods to prevent and control Necrotic Enteritis. This includes:
- Avoidance of animal by-products, rye, fish meal, wheat, barley in the diet.
- Administration of probiotics or competitive cultures.
- Treatment with antimicrobial-medicated drinking water
The response to treatment is considered to be overestimated because the disease is likely to be self-limiting in a flock.
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