2. Specimen (scope and application)
2.1 Scope
The test is a modified method based on Benedek (1943) and Boray & Pearson (1960). The test will detect the presence of trematode eggs or oocysts of the coccidian parasite Eimeria leuckarti. All stock being imported into WA requiring a test before entry and after entry should be tested using this method (FEST) to adhere to WA’s importation requirements.
The presence of trematode eggs does not always indicate the presence of live adult flukes and the absence of trematode eggs does not exclude trematode infection. Liver fluke and stomach flukes have a prepatent period of eight weeks or more depending on the animal species. After successful treatment with a flukicide, liver fluke eggs present in the bile ducts and gall bladder can continue to be shed for 10–20 days.
2.2 Application
Faeces can be used as collected. Trematode eggs will not hatch if the temperature is below 10 degrees Celsius and can survive unhatched in the faeces for more than six months. Faeces can be stored for months in the fridge prior to examination provided there is no overgrowth with fungus. However, they are susceptible to desiccation.
It takes 10–20 days for a miracidium to develop at a temperature of 16–20 degrees Celsius. Eggs only hatch if the temperature is above 10 degrees, there is short wave light and the eggs are surrounded by fresh water and not in direct contact with faecal material. Faeces kept at room temperature for less than 10 days are still suitable for examination.
The number of liver fluke eggs shed in faeces can be low. Some species (e.g. cattle) can shed less than 1 egg/gram and, in horses, excretion rates as low as 0.1 egg/g have been reported. The procedure described here is based on 4g (10g for horses and cattle) of faeces and the examination of the whole sediment. Sensitivity of the test is high (> 90%) if more than 10 eggs/g faeces are present. However, because lower egg counts are very common, the test is mainly recommended as a herd testing procedure. Overall, the sensitivity of the test is considered to be about 30–50%. If necessary, repeated analysis of 4g samples can be conducted to improve sensitivity.
The test procedure is not suitable for the detection of eggs from the small liver fluke Dicrocoelium dendriticum (not known to occur in Australia). There is no reliable method for the detection of this parasite except for liver examination at the abattoir.
2.3 Sample preparation
No special sample preparation is necessary.