Coccidiosis in Chickens

Coccidiosis is a disease that affects chickens, caused by tiny parasites called Eimeria. These parasites attack the intestines of the chickens, making them sick and sometimes leading to death. Chickens with coccidiosis may not grow well, have diarrhea, and appear weak. To help keep chickens healthy, it’s important to keep their living area clean, manage what they eat, and sometimes give them medicine or vaccines. Veterinarians and scientists are also working hard to find new ways to prevent and treat this disease.

What is Coccidiosis?

Coccidiosis occurs when chickens ingest infective oocysts (eggs) of Eimeria through contaminated feed, water, or litter. These oocysts release sporozoites, which invade the gut lining, causing damage and inflammation.

 

Etiology

• Coccidiosis is caused by tiny germs called Eimeria protozoa.
• Some common types of Eimeria that make chickens sick are:
  • Eimeria tenella
  • Eimeria acervulina
  • Eimeria maxima
  • Eimeria necatrix
  • Eimeria brunetti
• These germs can make chickens feel very sick, so it’s important to keep them healthy and safe.

 

Epidemiology

Global Spread of Chicken Sickness

• Global Spread:
  • First, this sickness is found in chickens all around the world. In particular, it is especially common in warm and humid places, where germs can thrive.
• Who Gets Sick:
  • Next, young chickens between 3 to 8 weeks old are most at risk of getting sick. However, adult chickens can also get sick, especially if they are stressed or not cared for properly.
• Risk Factors:
  • Furthermore, the sickness is more common on crowded farms where there are too many chickens. Additionally, poor cleaning practices can lead to more germs, increasing the chances of illness.

 

Predisposing Factors

Factors That Help Eimeria Spread in Chickens

• Crowded Conditions:
  • First, when too many chickens are kept together, it creates an environment where germs can grow easily. As a result, the chances of sickness increase because the germs can spread quickly.
• Warm and Humid Weather:
  • Next, hot and humid weather is perfect for germs to survive. In fact, this kind of weather helps them multiply faster, making it easier for chickens to get sick.
• Dirty Environments:
  • Additionally, if the chicken bedding is dirty and has germs in it, this raises the risk of illness. Thus, keeping the environment clean is important to protect the chickens from germs.
• Poor Nutrition:
  • Moreover, if chickens don’t eat the right food, their bodies can become weak. Therefore, when their bodies are weak, they are more likely to get sick from germs like Eimeria.
• Stress:
  • Lastly, things like overcrowding, moving to a new place, or changing their food can stress chickens. As a result, this stress can make them more vulnerable to getting sick.

 

Transmission

How Chickens Get Sick

• Fecal-Oral Route:
  • First, chickens can become sick by eating or drinking from contaminated food or water. For example, if the food or water has germs in it, the chickens can get sick.
• Environmental Factors:
  • Additionally, warm and wet conditions are perfect for germs to grow. This means that when the environment is hot and humid, more germs can multiply, making it easier for chickens to get sick.
• Mechanical Spread:
  • Moreover, the disease can spread through dirty equipment and shoes. Also, wild birds can carry germs and spread them to chickens. Therefore, keeping the environment clean is very important to prevent sickness.

Pathogenesis

• Ingested oocysts release sporozoites in the gut.
• Sporozoites invade epithelial cells, multiply, and destroy them.
• Damage causes diarrhea, nutrient malabsorption, and secondary infections.

 

Clinical Signs

Signs of Illness in Chickens by Type of Eimeria

E tenella

• Bloody Diarrhea: Chickens with this type often have diarrhea that has blood in it.

E necatrix

• Weight Loss and Poor Growth: Chickens can lose weight and have trouble growing because they can’t get enough nutrients from their food.

Eimeria acervulina and Eimeria maxima

• Dehydration: Diarrhea can make chickens very thirsty, leading them to lose a lot of water.

General Signs for All Types

• Pale Comb and Wattles: If the comb and wattles (the red parts on a chicken’s head) look pale, it might mean the chicken is losing blood and could be anemic (low on red blood cells).
• Depression and Lethargy: Infected chickens may look weak and want to be alone instead of playing or moving around.
• Ruffled Feathers: Chickens that don’t feel well may have messy, ruffled feathers.
• Reduced Feed Intake and Increased Thirst: Chickens may not want to eat much and will drink more water because their stomachs hurt.
• Drop in Egg Production: Hens that usually lay eggs may lay fewer eggs when they are sick.
• Sudden Death: In serious cases, some chickens can die quickly without any warning.

 

Postmortem Lesions

Signs of Intestinal Problems in Chickens Caused by Eimeria

• Caecal Cores (Eimeria tenella):
  Waste and dead tissue can build up in the ceca, which are special parts of the intestines. When this happens, the chicken may feel very sick.
• Internal Bleeding (Hemorrhages):
  Chickens can experience bleeding inside their bodies. This bleeding can vary depending on the type of Eimeria. For instance, Eimeria necatrix can cause more severe bleeding.
• Thickened Intestinal Walls (Eimeria acervulina):
  This type of Eimeria can cause the intestinal walls to swell and thicken. As a result, this condition can be painful and make it hard for the chicken to digest food.
• Swelling of the Ceca (Eimeria tenella):
  Eimeria tenella can lead to swollen ceca that look like balloons. This swelling is uncomfortable for the chicken.
• Damaged Intestinal Tissue (Eimeria maxima):
  Eimeria maxima can severely damage the intestines. This damage leads to a loss of important tissue, making it difficult for chickens to digest their food.
• Tiny Red Spots (Petechial Hemorrhages):
  You may notice tiny red spots of bleeding inside the intestines. These spots indicate where blood vessels have been damaged.
• Fibrin Membrane Formation (Eimeria brunetti):
  In serious infections from Eimeria brunetti, the chicken’s body creates a protective layer of protein called fibrin over the intestines.
• Yellow or White Intestinal Contents:
  The material inside the intestines may appear yellow or white. This change indicates a mix of dead tissue and food, which signals a problem.
• Blood Clots in the Ceca (Eimeria tenella):
  In severe cases, blood clots can form in the ceca due to Eimeria tenella. This condition is very dangerous and can threaten the chicken’s life.

If you notice any of these signs in your chickens, it is crucial to contact a veterinarian as soon as possible.

Diagnosis of Coccidiosis 

1. Clinical Signs
   • List observable signs like bloody droppings, ruffled feathers, lethargy, weight loss, etc.
2. Laboratory Methods
   • Microscopic Examination: Identify oocysts in feces.
   • Histopathology: Visualize tissue damage and parasites.
   • PCR (Polymerase Chain Reaction): Identify specific Eimeria species.
   • ELISA (Enzyme-Linked Immunosorbent Assay): Detect antibodies against Eimeria.
3. Molecular and Advanced Diagnostics
   • Whole-genome sequencing or qPCR for precise species identification.

Differential Diagnosis 

• Discuss diseases with similar clinical presentations to coccidiosis:
  1. Necrotic Enteritis (Clostridium perfringens)
  2. Histomoniasis
  3. Salmonellosis
  4. Aspergillosis
  5. Helminthiasis

Lesion Scoring of Coccidiosis 

• Describe lesion scoring as a critical tool in disease severity assessment.
• Mention Johnson and Reid’s Scoring System:
  • E. acervulina: Duodenal white plaques, thin intestinal walls.
  • E. maxima: Mid-intestinal ballooning, hemorrhagic lesions.
  • E. tenella: Severe cecal core, hemorrhage, bloody contents.

Comparative Table: Coccidiosis vs. Other Poultry Diseases

Disease	Symptoms	Lesions	Diagnostic Approaches
Coccidiosis	– Bloody diarrhea – Ruffled feathers – Weight loss – Lethargy – Poor growth rate	– E. acervulina: White plaques in duodenum, intestinal wall thinning – E. maxima: Hemorrhagic lesions, ballooning of the mid-intestine – E. tenella: Severe cecal lesions, blood-filled cecum	– Fecal Oocyst Count (microscopic examination) – Histopathology (intestinal samples) – PCR for Eimeria species – ELISA for antibodies against Eimeria
Necrotic Enteritis	– Diarrhea (often watery, not bloody) – Sudden mortality – Weakness – Reduced feed intake	– Extensive small intestinal lesions (necrosis) – Sloughing of intestinal mucosa – Gas-filled intestines	– Clostridium perfringens Culture (intestinal samples) – Histopathology (necrotic tissue) – PCR for C. perfringens
Histomoniasis	– Yellowish droppings – Head turning – Cyanosis (blue head) – Sudden death	– Lesions in the cecum and liver (necrosis, inflammation) – Black discoloration in liver	– Histopathology (liver and cecal samples) – PCR (to identify Histomonas meleagridis)
Salmonellosis	– Diarrhea – Dehydration – Lethargy – Greenish droppings with foul odor	– Septicemia: Patches of necrosis in intestines – Typhoid: Ulcers, inflammation in the cecum	– Salmonella Culture (feces or tissue samples) – Serology (for antibodies) – PCR for Salmonella spp.
Aspergillosis	– Respiratory distress – Nasal discharge – Poor weight gain – Loss of appetite	– Fungal plaques in lungs and air sacs – Yellow-green or white lesions in organs	– Fungal Culture (from respiratory tissues) – Histopathology (lung and air sac tissue) – PCR for Aspergillus spp.
Helminthiasis	– Diarrhea – Weight loss – Poor feed conversion – Swollen abdomen	– Intestinal inflammation – Enlarged intestines – Mucosal damage and eggs in feces	– Fecal Egg Count (microscopic examination) – Post-mortem Inspection for adult worms – PCR (for specific helminths)

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Lesion Scoring for Coccidiosis

In poultry, accurate lesion scoring helps assess the severity of coccidiosis. Johnson and Reid’s scoring system is commonly used for lesion scoring.

Eimeria Species	Lesion Scoring	Symptoms
E. acervulina	– Score 1: Mild, small, white lesions in the duodenum – Score 2: Moderate lesions, moderate mucosal damage – Score 3: Severe lesions, extensive mucosal damage	– Mild diarrhea – Moderate weight loss
E. maxima	– Score 1: Small, localized hemorrhages in the mid-intestine – Score 2: Extensive ballooning of the intestines – Score 3: Extensive hemorrhages and necrosis	– Bloody diarrhea – Severe weight loss
E. tenella	– Score 1: Mild cecal inflammation – Score 2: Hemorrhagic lesions, some cecal necrosis – Score 3: Severe hemorrhagic cecal lesions, full cecal necrosis	– Bloody cecal droppings – Lethargy

 

 

Prevention and Control

 Keep Things Clean

First, it’s very important to keep the chicken coop clean. Regularly clean and disinfect the coop to reduce harmful germs called oocysts. This way, you can help keep the chickens healthy and safe from illness.

 Manage Litter

Next, you should manage the litter properly. Frequently remove dirty bedding and replace it with fresh litter. By doing this, you can create a healthier environment for the chickens to live in.

Don’t Overcrowd

Additionally, make sure not to overcrowd the chickens in one space. When there are too many chickens together, it can lead to the quick spread of germs. Therefore, giving them enough space helps keep them safe.

 Use Medications

Moreover, you can use special medications to help prevent sickness. Adding anticoccidials to the chickens’ food or water can protect them from coccidiosis. This way, you can keep your flock healthy.

 Good Bacteria

Furthermore, giving the chickens probiotics and prebiotics is very beneficial. These good bacteria help support their stomachs and boost their immune systems. As a result, the chickens can better fight off diseases.

Vaccinate

Finally, remember to vaccinate your young chickens. Giving them vaccines helps them build strong defenses against illnesses. In this way, you can help ensure they grow up healthy and strong.

By following these tips, you can effectively prevent coccidiosis and keep your chickens happy!

Vaccination Schedule

Age of Chickens (Weeks)	Vaccine Type	Administration Method
1-2	Live Attenuated Vaccine	Oral (drinking water)
3-4	Live Oocyst Vaccine	Spray or Gel Application
6-8	Booster Vaccination (if necessary)	Through Drinking Water or Feed

 

Treatment

Anticoccidial Drugs

First, you can use special medicines called anticoccidial drugs. For example, Amprolium is one of these medicines that can help treat coccidiosis. Additionally, sulfa drugs and toltrazuril are also effective options. These medicines help the chickens feel better and fight off the disease.

Supportive Care

Next, it’s important to provide supportive care to the chickens. Specifically, this means giving them electrolytes and vitamins. By doing this, you can help them recover faster and, as a result, they will become stronger. Additionally, providing these nutrients can boost their overall health during the healing process. Furthermore, this extra care keeps their energy up during the healing process.

Rotate Medications

Finally, it’s a good idea to rotate the medications you use. When you change the types of medicines, it can prevent the coccidia from becoming resistant to them. As a result, this strategy helps ensure the medicines remain effective in treating the chickens.

• Natural Remedies:
  • Garlic and herbal supplements show some efficacy in controlling mild infections.
• Early diagnosis and targeted treatment improve recovery rates.
• Always consult a veterinarian for guidance.

By following these steps, you can help your chickens recover from coccidiosis and keep them healthy!

 

Conclusion

In conclusion, to manage coccidiosis successfully, farmers need to focus on three important areas: keeping the farm clean, taking preventive measures, and using the right treatments. First, by maintaining cleanliness on the farm, farmers can significantly reduce the chances of infection. Moreover, understanding what causes coccidiosis and how it spreads is essential. In addition, this knowledge helps farmers take proactive steps to prevent outbreaks. Ultimately, these actions create a healthier environment for the chickens.

Additionally, knowing how coccidiosis affects chickens allows farmers to create effective strategies. By implementing these strategies, they can save money and reduce losses in poultry farming. Ultimately, these efforts help keep the chickens healthy and contribute to the overall success of the farm.

Add also: Chicken Diseases

References

Taylor, M.A., Coop, R.L., & Wall, R.L. (2022). Veterinary Parasitology, 5th Edition. Wiley-Blackwell.

McDougald, L.R., & Reid, W.M. (2023). Coccidiosis in Poultry: The Importance of Management and Control, World Poultry Science Journal.

Chapman, H.D. (2024). Recent Advances in Coccidiosis Research: Epidemiology and Control. Journal of Avian Diseases.

Norton, R.A. (2024). Prevention and Management of Coccidiosis in Poultry Farms. International Journal of Poultry Science.

World Organization for Animal Health (OIE) (2023). Manual of Diagnostic Tests and Vaccines for Terrestrial Animals.

Conway, D. P., & McKenzie, M. E. (2007). Poultry Coccidiosis: Diagnostic and Testing Procedures. Wiley-Blackwell.

Merck Veterinary Manual: Coccidiosis in Poultry.

USDA Animal and Plant Health Inspection Service (APHIS) Poultry Disease Handbook.

Frequently Asked Questions (FAQs)