Section 3 | An Overview of Coccidiosis

Canadian Poultry
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How Do We Detect It? Diagnosis

To diagnose coccidiosis, there are typically 3 methods that are used1:

  1. Lesions found on post mortem examination
  2. Number of Eimeria in feces/litter/intestines
  3. Microscopic lesion scores


The most common method of diagnosis is to examine for lesions on a post mortem exam performed by your veterinarian. Each species of Eimeria will infect different portions of the intestinal tract and cause distinct lesions in the intestinal tract, as seen in the figure below. However, there are some limitations to this method as no lesions will be present in chickens with infections with few oocysts, and chickens may be infected with multiple species making it difficult to score lesions on post mortem.


Of the available methods, using microscopic lesion scoring is the best technique available1. Samples are collected during a post mortem exam and put under a microscope to evaluate the lesions present. This will allow specific detection of the species of Eimeria that is present and the severity of the disruption of the intestine.

Work with your veterinarian to help you identify the presence of Eimeria on your farm and determine what samples need to be taken. An early identification of the disease can lead to interventions that can mitigate its impact.


Ask the expert:

Use your eyes and ears! Canadian poultry experts recommend monitoring your flock multiple times a day. It is important to ensure (and not just rely on technology) that temperature and humidity is sufficient for optimal health and performance.

Identify birds that have died, and remove these animals as soon as possible. This is a key performance indicator.

It is important to strike a balance between disturbing birds and causing stress, as well as monitoring closely and identifying problems quickly before they become outbreaks.


  1. Jordan, B., G. Albanese, and L. Tensa. 2020. Coccidiosis in Chickens (Gallus gallus). Taylor & Francis Group, Boca Raton, FL, USA.