The latest report of the National Sheep Health Monitoring Project shows the percentage of sheep carcases infested with liver fluke almost doubled between 2020/21 to 2022/23.
Liver fluke (Fasciola hepatica) is a serious parasite of both sheep and cattle that can cause significant economic losses through reduced production, ill health and in some cases, death. Affected livers are condemned at abattoirs and in rare cases, whole carcases can be condemned.
National animal health and biosecurity organisation, Animal Health Australia, has monitored the incidence of 20 common animal health conditions in lamb and adult sheep since 2007.
In 2022/23, data from 9.8 million lamb and adult carcases were collected from 10 abattoirs throughout Australia.1 The sample represents about a quarter of the national slaughter and sheep from more than 10,000 individual properties.
Nationally, the percentage of inspected livers with liver fluke increased from 0.5 per cent to 0.9 per cent over the past two years, while the percentage of sheep under two years of age infected with liver fluke increased from 0.4 per cent to 1.1per cent.1
Historically, liver fluke-infested carcases were most prevalent in Tasmania but NSW claimed the dubious honour in 2022/23, with liver fluke detected in more than 2 per cent of all inspected livers.1
Central NSW was a particular ‘hot spot’, with 4.2 per ecnt of the 48,734 lamb livers inspected at Forbes abattoir between July and September 2023 giving liver fluke, a four-fold increase from the previous year.2
Liver fluke typically infests livestock in high rainfall (>600 mm) or irrigated regions in NSW, Victoria, Southern Queensland and Tasmania. Overall, about 15 per cent of Australian flocks are deemed to be at high or moderate risk.3
Permanent water, irrigation channels or wet conditions favour the survival of freshwater snails (the intermediate host), fluke eggs and larval fluke, increasing the risk of exposure of grazing livestock to infective stages. However, outbreaks can occur in other regions after significant rain events or via the introduction of livestock from endemic areas.
Livestock mainly ingest infective fluke cysts on vegetation over late summer and autumn as they graze wet areas, such as creeks, dams and springs. Ingested cysts release immature flukes and develop into early immature, late immature and adult fluke over an 8-10 week period in sheep and 10-12 weeks in cattle, causing serious tissue damage as they migrate through the liver from the intestine to the bile ducts.
This liver damage can significantly decrease growth rates and milk production, while blood loss can cause anaemia and eventually ‘bottle jaw’. Infested livestock are also susceptible to Black Disease and should be vaccinated against Clostridium novyi.
Effective control of liver fluke requires an integrated approach that combines grazing management, strategic treatment using an effective flukicide and rotating between different modes of action. Grazing should be managed to minimise exposure of young sheep and cattle, which are more susceptible to liver fluke, to pastures that have access to known wet areas.
All livestock in known endemic areas should be treated with an effective flukicide. Likewise, all introduced livestock should be treated, particularly if the treatment status is unknown.
The timing and selected mode of action of chemical treatment should be based on the likely stage of fluke infection in the animal and minimising the fluke egg burden on the pasture.
A flukicide with activity against early immature, late immature and adult stages of liver fluke should be administered in autumn. An additional treatment in late winter or early spring treatment using a different mode of action is recommended, particularly if ongoing wet conditions persist.
A mid-summer drench may also be required in some instances.
Regular monitoring using carcase feedback, antibody blood tests, and faecal egg count testing are also important to ensure control measures are working and to determine if treatment is necessary. Elanco has several options to control liver fluke and other parasites, including Fasinex 240, Exifluke 240, Fasimec Cattle and Bomectin F.
Fasinex 240 and Exifluke 240 are oral formulations containing triclabendazole. They are ideal for use during autumn or as part of a quarantine drench because they are effective against all three stages of triclabendazole-susceptible liver fluke. Fasinex 240 has the additional benefit of being registered for use in both sheep and cattle, making it suitable for use in mixed livestock enterprises.
Fasimec Cattle is an oral formulation of triclabendazole and ivermectin, which makes it a good option if broad spectrum parasite control is required in cattle.
Bomectin F is an injectable treatment that contains clorsulon and ivermectin for cattle. It is suitable as a late winter or early spring treatment to target adult fluke and as a rotation partner for triclabendazole-based treatments. With a nil milk withholding period, it can also be used in lactating dairy cows.
Always read and follow the label directions, and ensure good agricultural practices are followed for optimal parasite control. For further information and advice on managing liver fluke in sheep and cattle, contact your local Elanco representative.
