Shaping the future of animal health

Prevalence of liver fluke in cattle and how to test your herd

Liver fluke, Fasciola hepatica, is a parasite that infects cattle and sheep, but often goes undiagnosed because it shows no obvious signs or symptoms. It can however, be having a “hidden” or sub-clinical impact.

This impact may cause significant losses in productivity, costing producers millions of dollars. Liver fluke is thought to cost producers $50-$80 million per year in productivity losses alone3.

The distribution of liver fluke is generally known to be in the southern regions of Queensland, eastern aspects of NSW and widely through Victoria and eastern South Australia where rainfall is 600mm or more. Liver fluke is also known to become problematic in lower rainfall areas that utilise irrigation, or during drought when stock may congregate about areas of green pick at springs and watering places. To confirm this distribution, Virbac Animal Health conducted a study4 in cattle during 2004 across eastern Australia. The results were astonishing, particularly in Victoria. Overall, of over 700 properties tested, 55% were found to have liver fluke infections in stock. In Victoria, an astounding 70% had liver fluke infections in their cattle. NSW was the state with the second highest prevalence of 44%, with Tasmania rating third at 41%.

liver fluke map In addition to these high levels of prevalence was the fact that of all these infected herds, 66% were detected with the highest levels of herd infection possible (there are 4 levels of herd infection ratings). This means that 66% of liver fluke infected properties had greater than half of their herd infected, a level of infection likely to be causing significant production losses. In Victoria, 67% of infected herds rated at the highest level of herd infection, 64% in NSW and 75% in Tasmania.

Testing for liver fluke has traditionally been done by Faecal Egg Counts on fresh manure samples. This type of testing poses two inadequacies – it will only detect adult fluke, as they are the egg producing stage; and the test has very low sensitivity. (That is, the Faecal Egg Count will only detect infection approximately 50% of the time5.)

New technology has been developed to overcome some of these pitfalls of diagnosis using Faecal Egg Counts. An ELISA test has recently been commercialised by two state laboratories in Australia to increase accuracy of testing and diagnosis. An ELISA test is an Enzyme Linked ImmunoSorbent Assay – a test that detects the immune response of cattle (and sheep) to the liver fluke. This test is able to detect antibodies, or immune proteins, stimulated to develop by infection, and can be found in the blood or milk of infected stock. Hence, animals can be bled, or have a sample of milk taken for testing. Blood and milk testing is 98% accurate5, significantly more accurate than Faecal Egg Count Testing. This ELISA test is so sensitive that, in dairy cattle, testing can be done for a herd on a small sample of milk from the bulk milk vat. This type of testing can detect levels of infection that are likely to have a significant impact on herd productivity.

In dairy cattle, productivity can be affected in multiple ways. Liver fluke infections can lead to depression in milk yield, reduced milk quality, lower growth rates and reduced conception in heifers. A heavy liver fluke infection has been shown to cause a loss of up to 300 litres per cow per lactation2. This may cost around $75 per cow. In a herd of 100 cows, this equates to approximately $7500 per lactation.

To reduce this productive blow that liver fluke causes, the implementation of a liver fluke control programme is recommended, such as the Flukekill? Programme. The Flukekill? Programme was developed by Virbac, in conjunction with Dr. Joe Boray, a world authority on liver fluke. This programme aims to guide producers on when to treat for liver fluke, what chemicals to use, and to rotate chemical groups to avoid resistance development by liver fluke.

To implement this programme in a 100 cow dairy herd would cost approximately $1000 annually6. In comparison to losses in milk production of $7500, the cost benefit is potentially enormous.

Flukazole C (triclabendazole/oxfendazole synergistic combination) is a highly effective dry off treatment for liver fluke, controlling fluke down to 2 weeks of age with 100% efficacy (in comparison to 88.9% efficacy of triclabendazole only products)1. This can be used in combination with Virbamec Plus (ivermectin/clorsulon) during lactation to continue fluke control. Both products also provide broadspectrum worm control*.

References:
*See product label for details.
1. Dr. Joe C Boray, AT82, Virbac in House Data.
2. JG Ross (1970), The economics of Fiscal hepatica infections in cattle. British veterinary Journal, 126: xiii-xv
3. Dr. Joseph C. Boray. Liver fluke disease in sheep and cattle. NSW Agriculture Agfacts 1999.
4. Virbac in house data, Nov. 2004
5. Queensland Department of Primary Industries and Fisheries. Liver Fluke - Diagnosis of infection presentation (2004)
6. Based on approximate retail costs Nov.2004

Written by Jane Parker, BVSc, Technical Services Manager Food Producing Animals, Virbac Animal Health Australia, January 2005.
Disclaimer: The information provided in this article is meant as a guide only and is based on knowledge and understanding at the time of writing (Jan.2005). Readers should consult animal health professionals or their veterinarian for further information. Users of agricultural or veterinary chemicals should always read the label and any permit before using the product and comply strictly with directions.