Section 3 | An Overview of Coccidiosis

Canadian Poultry
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What to Look For: Clinical signs

The most common signs of coccidiosis occur in subclinical cases, where the symptoms found are vague and similar to those of many other diseases.


These symptoms may include:

  • Reduction in weight gain or egg production
  • Poor feed conversion
  • Reduced feed and water intake


In cases of subclinical disease, secondary infections, particularly with Clostridium, may occur. This is because the lining of the gut may become irritated, or the conditions within the gut may change allowing the proliferation of harmful, opportunistic bacteria. As described above, these animals may be consuming less feed, and may have less ability to defend themselves against invading bacteria such as Salmonella species.


When severe infections are present, some of the main clinical signs include:

  • A high percentage of visibly sick birds
  • Severe diarrhea and dehydration
  • High mortality
  • High number of culls