Poultry

Coccidiosis In Poultry: Prevention & Control

Coccidiosis in poultry, caused by Eimeria species, is a major challenge for poultry raised in deep litter systems, posing significant economic threats to the industry. This intestinal and cecal disease leads to high morbidity and mortality, driven by single-celled parasites from the Protozoa sub-kingdom. Eimeria species are highly host-specific, with each targeting a particular host. Globally, coccidiosis in poultry remains a pressing concern, prompting the poultry industry to invest heavily in prevention and treatment. The coccidiosis disease in poultry impacts bird’s health by causing malabsorption, poor feed conversion, reduced weight gain, and increased mortality, resulting in substantial financial losses.

What causes coccidiosis in poultry and why is it so prevalent?

Coccidiosis in poultry is caused by parasites commonly found in environments where hens are raised. Coccidia, the parasites responsible for the infection, rapidly reproduce and invade the lining of the intestine and caeca. Various Eimeria species can infect poultry directly, with no cross-immunity between them. Eimeria parasites follow a self-limiting life cycle, marked by high tissue and host specificity. Their pathogenic impact varies significantly, as highlighted in the Table.

Host	Eimeria	Location	Pathogenecity*
Chickens	E.acervuline	Duodenum, Jejunum	++
	E.brunetti	Illeum, Rectum	+++
	E.maxima	Duodenum, Jejunum, Rectum	++
	E.mitis	Duodenum, Jejunum	+++
	E.nectarix	Jejunum, Caeca	+
	E.praecox	Duodenum, Jejunum	+++
	E.tenella	Caeca	+++

*-non-pathogenic, +low pathogenic, ++ moderately pathogenic, +++ highly pathogenic

Coccidia are almost a constant presence in poultry operations, but clinical outbreaks only occur when susceptible birds—such as those immunosuppressed or battling other diseases—ingest large amounts of sporulated oocysts. Birds, whether sick or recovered, shed these oocysts through their feces, contaminating feed, water, litter, dust, and soil. Oocysts can spread further through equipment, footwear, insects like flies, and rodents. However, fresh oocysts only become infectious after sporulation, a process that takes 1–2 days under optimal conditions (70°–90°F with adequate moisture and oxygen). Once sporulated, these oocysts can survive in the environment for long periods, resisting common disinfectants but succumbing to freezing or extreme heat.

The severity of coccidiosis in poultry depends on various factors, including the bird’s genetics, nutrition, age, concurrent illnesses, and the specific Eimeria species involved. In chickens, Eimeria necatrix and E. tenella are the most harmful, causing severe intestinal hemorrhage. Other species like E. kofoidi and E. legionensis impact chukars, while E. lettyae is particularly dangerous for bobwhite quail. In pheasants, E. phasiani and E. colchici are highly pathogenic.

Although older birds tend to show greater resistance due to prior exposure, true age-related immunity doesn’t develop. Protective immunity is typically built through moderate, ongoing infections, helping birds withstand future challenges.

Coccidiosis in chickens signs and symptoms

Symptoms of coccidiosis in poultry can range from decreased growth rates, reduced feed and water intake, and weight loss to a noticeable drop in egg production. In more severe cases, symptoms of coccidiosis in poultry may exhibit severe diarrhea and high mortality. Even mild or subclinical infections can have serious consequences, often leading to secondary infections, particularly Clostridium spp.

Surviving birds typically recover within 10–14 days, but their growth and productivity may never fully rebound. The disease primarily targets the intestinal tract, leaving lesions with distinctive locations and appearances that aid in diagnosis. Early detection and intervention are crucial to minimizing the impact on poultry health and farm productivity.

Eimeria species, the parasites behind coccidiosis in poultry, cause varying levels of damage based on the site of infection. Here’s a closer look at their effects:

Eimeria tenella:
Infections are confined to the ceca and are recognizable by the accumulation of blood. Birds surviving the acute stage may show cecal cores—clotted blood, tissue debris, and oocysts—during necropsy.
Eimeria necatrix:
This species primarily affects the proximal and mid-small intestine, causing “salt and pepper” lesions—white spots mixed with bright or dull-red spots. Severe cases lead to thickened intestinal walls and dilated infected areas, filled with blood and mucus. Damage happens in the small intestine, but the sexual life cycle is completed in the ceca, where the oocysts are present.
Eimeria acervulina:
The most prevalent species creates whitish, oval patches in the upper small intestine. While lesions are easily identifiable, infections result in poor growth, increased culling, and slightly higher mortality rates in flocks.
Eimeria brunetti:
This species attacks the lower small intestine, rectum, ceca, and cloaca.The oocysts are larger than those of E. acervulina but have less economic impact. Severe cases involve coagulative necrosis and sloughing of the mucosa, disrupting the intestinal lining extensively.
Eimeria maxima:
Infections cause thickening and dilation of the small intestine walls, with petechial hemorrhage and reddish-orange exudates. Its oocysts and gametocytes are notably large, aiding in diagnosis.
Eimeria mitis:
This species affects the distal small intestine, causing indistinct lesions. It is distinguishable by small, round oocysts.
Eimeria praecox:
Infecting the proximal small intestine, it does not form distinct lesions but can impair growth. Although the oocysts are bigger than those of E. acervulina, they are of lesser economic importance.
Eimeria hagani and Eimeria mivati:
These species develop in the proximal small intestine. Although E. hagani causes subtle lesions, E. mivati can inflict severe damage akin to E. acervulina. Their classification remains debated, with some considering them variations of existing species.

Understanding the distinct characteristics and impacts of these Eimeria species is crucial for effective diagnosis and management of coccidiosis in poultry.

Diagnosing coccidiosis in poultry involves various laboratory techniques. Common practices include counting coccidia per gram of feces and microscopic examination of oocysts. Advanced methods employ rRNA and rDNA probes to identify specific Eimeria species through unique restriction fragment patterns. Additionally, random amplified polymorphic DNA (RAPD) assays distinguish between species such as E. acervulina, E. tenella, and their strains, offering accurate insights for effective management.

How to prevent coccidiosis in chickens?

Prevention is the best cure for coccidiosis in poultry. Some normal steps can be taken to reduce the chances of coccidiosis disease in poultry.

1. Poultry House Management

An effective strategy to prevent coccidiosis in poultry is the regular removal of caked litter from poultry houses every 2–3 weeks, followed by the application of fresh litter before introducing new flocks. Monthly litter cleaning is also crucial for maintaining hygiene and minimizing infection risks.

2. Role of Fats in Coccidiosis Management

Fats rich in docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and linoleic acid—sourced from fish oils and flaxseeds—have been shown to reduce the severity of Eimeria tenella infections in young broiler chicks. Diets supplemented with 2.5%–10% flaxseed oil or 10% linseed oil significantly decrease cecal lesions, parasitic invasion rates, and development, offering a promising nutritional approach to managing coccidiosis disease in poultry.

3. Antioxidants

Antioxidant molecules play a vital role in controlling and reducing oxidative stress caused by elevated levels of reactive oxygen species and free radicals. These molecules can prevent chain reactions within cells that lead to severe damage or cell death. Utilizing antioxidants from natural sources helps restore the oxidant balance, aiding in the recovery of birds affected by coccidiosis.

For example, curcumin, derived from Curcuma longa, has demonstrated potential in alleviating lesions induced by E. acervulina and E. maxima in the upper and middle parts of the small intestine.Similarly, artemisinin, derived from Artemisia annua, has proven effective in reducing oocyst shedding in infections caused by E. acervulina, E. tenella, and E. maxima, supporting a natural approach to managing the disease.

4. Essential Oils

The use of essential oils in poultry diets to control coccidiosis has gained attention recently. Oils like tea tree, thyme, and artemisia have demonstrated exceptional efficacy in destroying oocysts. This approach offers a promising natural treatment for coccidiosis in chickens, reducing reliance on synthetic drugs and promoting sustainable poultry farming.

5. Herbal Extracts and Medicinal Plants

Certain plant extracts also exhibit anticoccidial properties. Research assessing the effects of 15 different herbs revealed that Ulmus macrocarpa, Pulsatilla koreana, and Torilis japonica significantly improved survival rates in day-old infected broilers, showcasing their potential as natural solutions for coccidiosis management.

How to control coccidiosis disease in poultry?

Coccidiosis can severely impact poultry health and productivity, but proactive management can significantly reduce the risks. Start by maintaining vigilance—act promptly when the first symptoms appear to prevent the disease from spreading. Segregate birds of different age groups to minimize cross-contamination and ensure that the litter remains dry yet not dusty, as wet litter or dusty litter can exacerbate outbreaks. Pay special attention to watering points; avoid overflow and keep the area dry. High standards of hygiene are critical, including the cleanliness of feeding and drinking equipment and personnel handling. As chicks grow, adjust drinkers’ height to prevent fouling. Lastly, consider vaccination when disease risks are high to build a robust line of defense. By integrating these measures, poultry farmers can create a healthier environment, safeguarding their flocks against coccidiosis.