Sampling and Diagnosis

Diagnosis of the disease on the farm can be made based on symptoms and the history of the disease on the farm. On farms without historical information diagnosis could be difficult as clinical symptoms precede the shedding of oocysts.

Sampling and monitoring the presence of Eimeria in faecal samples provides a good overview of the presence of coccidiosis in the herd and may give a picture of the course of infection in the case of repeated sampling. In order to establish the real status of coccidiosis in the herd, the Eimeria species present in the animals must be identified.

Some important points to follow when faecal samples are taken:

• Collect individual samples directly from rectum with a plastic glove (at least 4 to 10 grams per sample).
• Samples should be taken when coccidiosis is suspected according to herd history.
• Pool samples of 3 to 5 animals from the same age group.
• Refrigeration is not necessary if examined within 1-2 days.
• Samples can be refrigerated (4°C) for several days.
• Refrigeration is not required for shipping.
• Close containers tightly for shipping to a laboratory.

The identification of the species involved in provoking the clinical symptoms is based on the morphology of the oocysts. With some experience it is possible to identify at least the three pathogenic species (Eimeria bovis, Eimeria zuernii and Eimeria alabamensis) infecting cattle with high precision without sporulating them, directly in the fresh faeces.

The results from the diagnostic laboratory should be interpreted with caution because the oocyst excretion pattern varies over the time, and the results may or may not correlate with clinical signs. The OPG count could also be misleading without identifying the species and knowing course of the disease. For example an OPG count of 1,000 oocyst could be from the start, peak or end of the oocyst shedding during the course of infection. This could complicate the interpretation.

It is also very important to have the herd history in mind.