The initially dry but latterly unsettled weather experienced in August has seen a return to more typical conditions for parts of the UK, whilst in others the warmer, drier weather experienced so far this season has continued. The overall UK average temperature in August 2018 was 15.3°C, 0.3°C above the long term average (1981-2010 data), whilst rainfall for the UK was 95% of the long term average.
Regionally, average temperatures were comparable to the monthly average for all regions of Scotland and Northern Ireland, and above average for all regions of England and Wales. The average temperatures over the previous 3 months (June – August 2018) was above average across all regions. Rainfall varied around 10-20% above and below the long term average across all regions, while the average rainfall for all three previous months was below the long term average for all regions.
The provisional fluke forecast for Autumn 2018 is based on monthly rainfall and temperature data from May-August 2018.
This provisional forecast is currently predicting low risk across the UK at the regional level (Figure 1), although it should be noted that some parts of western Scotland have been flagged as medium to high risk. These risk levels may change based on the weather experienced in September and October.
Figure 1: Current regional risk for liver fluke in Autumn 2018 is low. However, local conditions should be taken into consideration when evaluating on farm risk
It is important to note, as highlighted in a recent joint press release issued by the working groups for sustainable parasite control in sheep and cattle (Sustainable Control of Parasites in Sheep or “SCOPS” and Control Of [cattle] Worms Sustainably or “COWS”), that local factors must also be taken into account when considering on farm risk from liver fluke. The dry hot weather does not necessarily guarantee low infection levels on all farms or even between different areas on individual farms.
Development of liver fluke and its intermediate host, the mud snail (Galba truncatula; Figure 2) on pasture is dependent upon temperature and rainfall with warm wet conditions optimal. On farms with permanently wet areas and/or permanent water bodies snails may therefore continue to thrive in hot weather.
Figure 2: A large number of mud snails (Galba truncatula) recovered from a farm in Lancashire, August 2018. While the current dry weather indicates lower risk for liver fluke consideration should be given to on farm conditions relating to local rainfall and wetlands. Photo credit: Bethan John, University of Liverpool.
Despite the overall low predicted risk, continued vigilance for signs of disease and on farm contingency plans in the event of an outbreak are of great importance at this time of year in the context of liver fluke on your farm.
Advised actions include:
Figure 3: Acute liver fluke infection may be easily detected at post-mortem as parasitic tracks on the liver. Acute disease is more common in sheep (pictured) compared to cattle. Where outbreaks of disease occur, post-mortem of lost stock is a useful way of confirming diagnosis and ensuring correct treatment.
Where acute disease occurs, treatment with triclabendazole is recommended as this is the only product effective against both adult and immature stages of the parasite.
All animals coming onto farm should be considered a potential source of parasites. Where buying in new stock, quarantine measures should be taken. This includes worms, for which the introduction of resistant strains is of particular concern, and ectoparasites (i.e. lice and mite infestations) such as a recent outbreak of Psoroptic mange in cattle reported in September 2018 by the Animal and Plant Health Agency’s Veterinary Investigation Centre in Carmarthen.
For sheep, current best practice advised by SCOPS is as follows:
To prevent introduction of resistant roundworms and sheep scab:
Where resistant liver fluke is a concern:
For cattle, COWS guidelines highlight the importance of knowing disease status of purchased animals or their farm of origin.
For more information concerning the implementation of effective on farm quarantine procedures please speak to your vet.
Whilst the warm and dry summer months have resulted in to relatively low risk season for roundworm infections in grazing livestock, recent unsettled spells of rainfall and continued warm weather may introduce some risk into the late grazing season. Many of the disease-causing roundworm larvae will remain infective on grazing pastures to the end of the season. It is therefore important to maintain vigilance for signs of disease in at risk animals grazing potentially contaminated pastures:
PGE is a disease of lambs in their first grazing season, whilst haemonchosis may affect both lambs and ewes.
Advised actions include:
Figure 4: Anaemia can be seen as pale mucus membranes, particularly around the eyes. Anaemia is a common sign in heavy infections of blood feeding parasites such as Haemonchus contortus and Fasciola hepatica.
Lungworm larvae may survive drier periods of weather within faecal pats to be dispersed onto pasture en masse following periods of rainfall, such as those recently experienced. Cases have been recently detected in Scotland (Figure 5) and, naïve animals such as unvaccinated calves in their first grazing season or bought-in dairy cattle on farms with a known history of disease could still be at risk.
Figure 5: Clinical cases of lungworm similar to above have been detected in parts the UK in September 2018.
Advised actions include:
Figure 6a and 6b Early signs of lungworm infection include widespread coughing and elevated respiratory rates.
Housing presents an opportunity in the ongoing control of parasitic disease on farm. Worm burdens acquired over the grazing season may be targeted effectively at this time without risk of animals becoming re-infected. There are also benefits on growth and feed efficiency associated with treating cattle for fluke at housing. As is the case during the grazing season, any treatments administered should be based on evidence of infection, such as clinical disease and/or diagnostic testing (e.g. worm egg counts).
Treatment efficacy should also be considered at this time since ineffective treatments may result in a continued parasitic burden (with associated reductions in productivity) and potential pasture contamination with resistant parasites at turn-out the following grazing season.
For more information please speak to your vet, or visit the COWS website.
Figure 7: Pour-on preparations of 3-ML wormers are also effective in controlling sucking and chewing lice.
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