Is rumen fluke a growing threat to livestock?
Rumen fluke prevalence has risen in Ireland over recent years, and it is now known to be more prevalent than liver fluke, with 52% of Irish cattle found to be infected at slaughter.1 It is a parasite of cattle and sheep and clinical disease is rare. However, cattle seem to be most affected, and the regional veterinary laboratory service has even recorded fatal cases. With changing weather patterns, is this a parasite we need to be more aware of?
Why this year could be a particular threat:
Like liver fluke (Fasciola hepatica), rumen fluke has a complicated life cycle involving a mud snail intermediate host. The only recorded rumen fluke in Irish cattle, Calicophoron daubneyi, relies on the same snail species, Galba (Lymnaea) truncatula, as liver fluke. This means the lifecycle relies on favourable habitat and climatic conditions – putting counties with warmer, wetter climates at higher risk.2 With this year’s wet weather patterns, and data to suggest a spike in rumen fluke related deaths in years with unusually high rainfall, it is important to be vigilant for cases, especially in first season grazing cattle.1 The Department of Agriculture Animal Health Surveillance Unit released a statement towards the end of the summer to comment on the high parasite burdens being seen:3
“Due to the mild wet winter which has been followed since by mild and continuous wet weather there is risk of increased parasitic worm burden in grazing animals. With increased worm burden comes reduced productivity and increased clinical disease and potential deaths in our livestock. As well as parasitic gastroenteritis, which is a perennial problem at this time of the year, Regional Veterinary Laboratories report significant issues caused by liver fluke, and on some farms, rumen fluke.”
A similar warning was given in 2023 for higher rainfall regions commenting that “cases typically occur late in the grazing season” and “in weanlings at the end of their first grazing season”.4
Rumen fluke lifecycle:
Adult rumen fluke reside in the rumen and lay eggs which are passed onto the pasture in the faeces. At suitable temperatures, these eggs hatch into miracidia which infect mud snails. They then develop within the snail through several stages, and emerge as cercaria, which encyst on grass as metacercaria – the infectious stage to ruminants. These are ingested by grazing animals and the rumen fluke larvae are released in the small intestine, feeding on intestinal mucosa, before migrating to the rumen and reticulum where they mature and lay eggs.
Signs to look out for and diagnosis:
Although prevalence is high, rumen fluke (unlike liver fluke) is generally regarded as low significance in terms of health and production effects. Clinical disease is rare and is generally caused by large numbers of immature rumen fluke in the small intestine causing damage to the mucosa. This makes diagnosis challenging, as faecal egg testing relies on the presence of egg laying adults. This being said, it is still worth running a faecal analysis on suspected cases, as animals exposed to high infection burdens will often also have adult rumen flukes, and therefore eggs, present. In very severe cases the Irish Regional Veterinary Laboratories have even detected large numbers of immature rumen flukes in faecal samples.
Clinical signs are vague and non-specific, including, ill thrift, rapid weight loss, diarrhoea and dehydration. Low albumin (a blood protein) may be seen on blood tests, and this with the listed clinical signs and a history of grazing wet ground would be highly indicative of clinical rumen fluke. Mixed infections with other parasites, particularly liver fluke, are common and clinical signs can be very similar and difficult to attribute to one or the other, so a postmortem would confirm diagnosis.
Control and treatment:
Control measures designed to reduce the incidence and severity of liver fluke will also have beneficial effects in controlling rumen fluke. This includes restricting access to wet and water-logged grazing to avoid the mud snail’s preferred habitat and therefore exposure to infection.
There are no licensed treatments for rumen fluke. Oxyconazide is the only flukicide with known action against both immature and adult forms of rumen fluke. However, it is only currently licenced to treat adult liver fluke and tapeworms. Therefore, it’s use to treat rumen fluke should be under veterinary direction and must require evidence of disease and the need to treat. The presence of rumen fluke eggs in cattle which are thriving is not a reason to treat, and routine treatment is not recommended.
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Is rumen fluke a growing threat to livestock?
Rumen fluke prevalence has risen in Ireland over recent years, and it is now known to be more prevalent than liver fluke, with 52% of Irish cattle found to be infected at slaughter.1 It is a parasite of cattle and sheep and clinical disease is rare. However, cattle seem to be most affected, and the regional veterinary laboratory service has even recorded fatal cases. With changing weather patterns, is this a parasite we need to be more aware of?
Why this year could be a particular threat:
Like liver fluke (Fasciola hepatica), rumen fluke has a complicated life cycle involving a mud snail intermediate host. The only recorded rumen fluke in Irish cattle, Calicophoron daubneyi, relies on the same snail species, Galba (Lymnaea) truncatula, as liver fluke. This means the lifecycle relies on favourable habitat and climatic conditions – putting counties with warmer, wetter climates at higher risk.2 With this year’s wet weather patterns, and data to suggest a spike in rumen fluke related deaths in years with unusually high rainfall, it is important to be vigilant for cases, especially in first season grazing cattle.1 The Department of Agriculture Animal Health Surveillance Unit released a statement towards the end of the summer to comment on the high parasite burdens being seen:3
“Due to the mild wet winter which has been followed since by mild and continuous wet weather there is risk of increased parasitic worm burden in grazing animals. With increased worm burden comes reduced productivity and increased clinical disease and potential deaths in our livestock. As well as parasitic gastroenteritis, which is a perennial problem at this time of the year, Regional Veterinary Laboratories report significant issues caused by liver fluke, and on some farms, rumen fluke.”
A similar warning was given in 2023 for higher rainfall regions commenting that “cases typically occur late in the grazing season” and “in weanlings at the end of their first grazing season”.4
Rumen fluke lifecycle:
Adult rumen fluke reside in the rumen and lay eggs which are passed onto the pasture in the faeces. At suitable temperatures, these eggs hatch into miracidia which infect mud snails. They then develop within the snail through several stages, and emerge as cercaria, which encyst on grass as metacercaria – the infectious stage to ruminants. These are ingested by grazing animals and the rumen fluke larvae are released in the small intestine, feeding on intestinal mucosa, before migrating to the rumen and reticulum where they mature and lay eggs.
Signs to look out for and diagnosis:
Although prevalence is high, rumen fluke (unlike liver fluke) is generally regarded as low significance in terms of health and production effects. Clinical disease is rare and is generally caused by large numbers of immature rumen fluke in the small intestine causing damage to the mucosa. This makes diagnosis challenging, as faecal egg testing relies on the presence of egg laying adults. This being said, it is still worth running a faecal analysis on suspected cases, as animals exposed to high infection burdens will often also have adult rumen flukes, and therefore eggs, present. In very severe cases the Irish Regional Veterinary Laboratories have even detected large numbers of immature rumen flukes in faecal samples.
Clinical signs are vague and non-specific, including, ill thrift, rapid weight loss, diarrhoea and dehydration. Low albumin (a blood protein) may be seen on blood tests, and this with the listed clinical signs and a history of grazing wet ground would be highly indicative of clinical rumen fluke. Mixed infections with other parasites, particularly liver fluke, are common and clinical signs can be very similar and difficult to attribute to one or the other, so a postmortem would confirm diagnosis.
Control and treatment:
Control measures designed to reduce the incidence and severity of liver fluke will also have beneficial effects in controlling rumen fluke. This includes restricting access to wet and water-logged grazing to avoid the mud snail’s preferred habitat and therefore exposure to infection.
There are no licensed treatments for rumen fluke. Oxyconazide is the only flukicide with known action against both immature and adult forms of rumen fluke. However, it is only currently licenced to treat adult liver fluke and tapeworms. Therefore, it’s use to treat rumen fluke should be under veterinary direction and must require evidence of disease and the need to treat. The presence of rumen fluke eggs in cattle which are thriving is not a reason to treat, and routine treatment is not recommended.
Rumen fluke lifecycle:
Adult rumen fluke reside in the rumen and lay eggs which are passed onto the pasture in the faeces. At suitable temperatures, these eggs hatch into miracidia which infect mud snails. They then develop within the snail through several stages, and emerge as cercaria, which encyst on grass as metacercaria – the infectious stage to ruminants. These are ingested by grazing animals and the rumen fluke larvae are released in the small intestine, feeding on intestinal mucosa, before migrating to the rumen and reticulum where they mature and lay eggs.
Signs to look out for and diagnosis:
Although prevalence is high, rumen fluke (unlike liver fluke) is generally regarded as low significance in terms of health and production effects. Clinical disease is rare and is generally caused by large numbers of immature rumen fluke in the small intestine causing damage to the mucosa. This makes diagnosis challenging, as faecal egg testing relies on the presence of egg laying adults. This being said, it is still worth running a faecal analysis on suspected cases, as animals exposed to high infection burdens will often also have adult rumen flukes, and therefore eggs, present. In very severe cases the Irish Regional Veterinary Laboratories have even detected large numbers of immature rumen flukes in faecal samples.
Clinical signs are vague and non-specific, including, ill thrift, rapid weight loss, diarrhoea and dehydration. Low albumin (a blood protein) may be seen on blood tests, and this with the listed clinical signs and a history of grazing wet ground would be highly indicative of clinical rumen fluke. Mixed infections with other parasites, particularly liver fluke, are common and clinical signs can be very similar and difficult to attribute to one or the other, so a postmortem would confirm diagnosis.
Control and treatment:
Control measures designed to reduce the incidence and severity of liver fluke will also have beneficial effects in controlling rumen fluke. This includes restricting access to wet and water-logged grazing to avoid the mud snail’s preferred habitat and therefore exposure to infection.
There are no licensed treatments for rumen fluke. Oxyconazide is the only flukicide with known action against both immature and adult forms of rumen fluke. However, it is only currently licenced to treat adult liver fluke and tapeworms. Therefore, it’s use to treat rumen fluke should be under veterinary direction and must require evidence of disease and the need to treat. The presence of rumen fluke eggs in cattle which are thriving is not a reason to treat, and routine treatment is not recommended.