Faecal egg count reduction test

The fecal egg count reduction test (or FECRT) was suggested in the The World Association for the Advancement of Veterinary Parasitology (WAAVP) guideline for estimating the reduction in fecal egg counts (FECs) and its corresponding confidence interval. The results of this test can be used to determine the anthelmintic resistance status of the animals.

Generally an analytical sensitivity of 50 is used, 15 is also possible if a greater sensitivity is desired. In order to reduce the counting variability, using groups of at least 10-15 animals was suggested, depending on the animal species of interest. In addition, the mean pre-treatment FECs should be at least 150 eggs per gram (epg), otherwise the FECRT can give unreliable results.

Suppose a group of ${\displaystyle n_{T}}$ animals received anthelmintic treatment and a group of ${\displaystyle n_{C}}$ animals serves as control. The percentage reduction in FECs can be calculated as

${\displaystyle {\text{Percentage reduction }}=100\times \left(1-{\frac {{\bar {x}}_{T}}{{\bar {x}}_{C}}}\right)}$

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