Introduction
Necrotic enteritis in poultry is caused by Clostridium perfringens and serotypes responsible for our Type A and B . Mostly young broilers are affected, but sometimes laying hens ( birds of 4 weeks of age or older) are affected. High-protein feed, intestinal obstruction, and coccidiosis infections create an environment for the growth and infection of C. perfringes in poultry.
Causative Agent:
- Caused by Clostridium perfringens, a gram-positive, obligate anaerobe.
- Grows on blood agar at 37°C (98.6°F), producing a distinct double zone of hemolysis.
Types Involved:
- C. perfringens Types A and C are most commonly linked to necrotic enteritis in poultry.
- Bacteria produce toxins that damage the small intestine and liver.
Environmental Presence:
- Ubiquitous in soil, dust, feces, feed, and used poultry litter.
- Naturally inhabits the intestines of healthy birds without necessarily causing disease.
Triggers & Predisposing Factors:
- The disease develops when the intestinal balance is disrupted or mucosal damage occurs.
- Common triggers include:
- Intestinal disturbances: Coccidiosis, mycotoxicosis, salmonellosis, ascaridiasis.
- Dietary factors: High levels of animal by-products (e.g., fish meal), wheat, barley, oats, or rye.
- Slow intestinal transit: Promotes bacterial overgrowth and toxin production.
Pathogenesis
- Colonization: C. perfringens overgrows in the small intestine, aided by gut disruptions (e.g., coccidiosis, diet changes).
- Toxin Production: Key toxins like NetB (pore-forming) and alpha toxin (membrane-damaging) are released.
- Mucosal Damage: Toxins destroy intestinal epithelial cells, causing necrosis, ulceration, and hemorrhage.
- Inflammation: Immune response worsens tissue injury, impairing nutrient absorption.
- Systemic Spread: Severe cases lead to bacteremia, septicemia, and death.
Disease Duration & Mortality:
- Outbreaks last 5–14 days in an affected flock.
- Mortality ranges from 2% to 50%, depending on severity.
Clinical findings
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Primary Clinical Sign:
- The sudden increase in flock mortality is often the first and only noticeable symptom.
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Additional Symptoms:
- Affected birds may show:
- Lethargy and depression.
- Ruffled feathers.
- Diarrhea
- loss of appetite
- unwillingness to move
- Gross Lesions:
- Primarily found in the small intestine (jejunum and ileum).
- Characteristic findings:
- Intestines may appear ballooned, fragile, and distended with foul-smelling, brown fluid.
- The mucosa is covered with a tan-to-yellow pseudomembrane(Turkish Towel appearance), which sometimes takes on a diphtheritic-like appearance.
- The coloration, ranging from light orange to deep brown, is likely due to fresh or oxidized blood mixed with bile staining.
- In severe cases, epithelial sloughing may occur, with lesions either localized or extending throughout the intestine.
Diagnosis
Presumptive Diagnosis
- Clinical signs: diarrhea, depression.
- Gross lesions: thickened, necrotic small intestine.
Confirmation
- Microscopy: Gram-positive rods in mucosal scrapings.
- Histology: Coagulative necrosis, bacterial rods in debris.
- Bacterial Isolation: C. perfringens with double-zone hemolysis on blood agar.
- Note: Use selective media for accurate identification.
Differential Diagnosis
- Coccidiosis: Eimeria brunetti causes less severe lesions.
- Ulcerative Enteritis: C. colinum causes focal lesions and hepatic necrosis.
Treatment for Necrotic Enteritis
Antibiotics for Treatment (Administered in Drinking Water):
- Amoxicillin
- Ampicillin
- Chloramphenicol
- Ciprofloxacin
- Doxycycline
- Neomycin
- Erythromycin
- Furazolidone
Antibiotics for Reducing Fecal Shedding (Administered in Feed):
- Lincomycin
- Tylosin
- Bacitracin
- Furazolidone
Prevention and Control
1. Prevent Coccidiosis
- Control Eimeria acervulina and Eimeria maxima infections.
- Use coccidiosis vaccines (modified live or recombinant).
- Historically managed with anticoccidial feed additives (virginiamycin, bacitracin, lincomycin, ionophores).
2. Dietary Management
- Avoid excessive animal by-products, wheat, barley, rye, and fish meal.
- Add enzymes to improve digestion if feeding wheat, barley, or rye.
3. Probiotics & Competitive Cultures
- Supplement feed with probiotics to prevent C. perfringens overgrowth.
FAQ’s
. What is Necrotic Enteritis (NE)?
- Bacterial infection by Clostridium perfringens, causes intestinal necrosis, inflammation, and mortality.
2. What causes NE?
- Overgrowth of C. perfringens due to high-protein diets, gut damage (e.g., coccidiosis), poor sanitation, or stress.
3. What are the signs?
- Acute: Sudden death, dark diarrhea.
- Chronic: Poor growth, diarrhea.
- Post-mortem: Thickened, necrotic intestines.
4. How is it diagnosed?
- Clinical signs, post-mortem lesions, and lab tests for C. perfringens.
5. How is NE treated?
- Antibiotics (e.g., bacitracin), probiotics, and addressing predisposing factors.
6. Can it be prevented?
- Yes, via biosecurity, balanced diets, coccidiosis control, and feed additives (probiotics, prebiotics).
7. Is NE zoonotic?
- No, but C. perfringens can cause human foodborne illness.
