Coccidiosis is one of the most common parasitic disease with the greatest economic impact on poultry farming. Caused by protozoa of the genus Eimeria, coccidiosis in poultry affects the intestinal health of animals, leading to significant losses due to mortality and reduced growth.

What is coccidiosis in poultry?

Coccidiosis is a parasitic disease caused by protozoa of the genus Eimeria, which infect and multiply within the cells of the digestive tract of poultry. These parasites can cause severe damage to the intestines, significantly compromising nutrient absorption and leading to weight loss and, in severe cases, death of the animals.

This health problem is common in several poultry species and can also affect other animals, such as cattle, pigs, and horses. Modern poultry production practices, which often involve confinement in large numbers, facilitate the transmission and spread of the disease within poultry houses.

Although oocysts, or Eimeria eggs, can be carried by wild birds, these parasites are specific to their hosts and, therefore, wild birds do not act as biological reservoirs of the disease.

The prevalence of Eimeria oocysts varies significantly depending on the farming system: in intensive systems, an infection rate of 92.7% has been reported, while in extensive systems this figure ranges from 25.3% to 58.9%. Semi-intensive systems have a prevalence of 78.3%.

Factors such as climate, facility management, poultry genetics, and immune status also influence the prevalence of coccidiosis, even in less intensive systems.

Symptoms of coccidiosis in poultry

The main symptoms and signs of coccidiosis in poultry include:

· Lethargy: affected poultry often shows signs of apathy, fatigue, prostration. Behavioral changes such as feather curling, ruffling and disinterest in their surroundings are also common.

· Weight loss: poultry may show anemia and reduced body weight, as well as dehydration.

· Low skin pigmentation: in poultry that have the ability to pigment, a noticeable decrease in color intensity is observed due to reduced intestinal absorption.

· Severe diarrhea (sometimes bloody): one of the most visible signs of coccidiosis is watery feces (diarrhea) with fresh blood or digested blood with mucus (particularly in the case of infection by E. tenella and E. necatrix). .

· Grouping: poultry tend to huddle together as if they were cold, which is typical behavior when they are uncomfortable and trying to maintain their body temperature.

In addition, clinical signs of the disease can be observed during regular inspections and through post-mortem analysis, where they are classified according to the Johnson and Reid system. This system assesses the severity of intestinal lesions on a scale from 0 (no visible lesions) to +4 (extremely severe lesions).

The severity of these symptoms may vary depending on the species of Eimeria involved and the immune status. Coccidiosis in poultry is also characterized by specific macroscopic lesions that can be seen in the intestines of animals.

How to diagnose coccidiosis in poultry?

The diagnosis of coccidiosis is made by observing clinical symptoms and macroscopic lesions in the intestines of poultry, classified by the Johnson and Reid method. This system assesses the severity of lesions on a scale from 0 (no visible lesions) to +4 (most severe lesions), taking into account the location, appearance, and severity of the lesions, which vary depending on the species of Eimeria involved.

In addition, monitoring the intestinal health of poultry is essential, especially to detect subclinical cases of coccidiosis. It is recommended to evaluate at least five clinically healthy poultry from 7 days of age at weekly intervals until they reach market age. This analysis includes a thorough examination of the intestinal tract, from the serosa to the mucosa, and many broiler production companies conduct regular necropsy sessions to identify the presence of subclinical diseases, known as “coccidial tests.”

Molecular detection, such as polymerase chain reaction (PCR), is another valuable tool in the diagnosis of coccidiosis. This technique allows the specific identification of the Eimeria species present by analyzing samples collected from the litter in the houses, providing an accurate diagnosis and the possibility of more targeted interventions.

Conclusion

The economic impact of coccidiosis in poultry farming represents a significant challenge for modern poultry farming, as well as for the health and productivity of production in Europe. With varied and potentially severe symptoms, this disease requires vigilance and accurate diagnosis. The use of the Johnson and Reid method to evaluate macroscopic lesions, together with advanced techniques such as PCR for the molecular detection of Eimeria species, are fundamental in the monitoring and control of the disease.

Effective coccidiosis management is not limited to treating symptoms but involves an integrated approach that includes environmental and nutritional management of birds. In our next blog post, we will explore best practices for managing coccidiosis in poultry, prevention and control strategies, as well as effective natural solutions, detailing how proper practices can reduce the incidence of the disease and improve the overall health of production birds.

Stay tuned for more information and insights on how to protect your birds from one of the most costly diseases in poultry farming.