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The first few days of July have continued with the wet conditions.
Unsettled weather with heavy possibly thundery showers and sunny spells is expected until around mid-month, when conditions may get a little warmer and drier, especially in the south and east.
The rest of the summer is expected to remain warmer than average, but with fewer hot and sunny spells than previous years. Rainfall is expected to be above average in the north of the UK but closer to average in the south.
Liver Fluke Forecast
Sheep Nematodes
Nematodirus
Cattle Nematodes
Coccidiosis
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Click charts for temperature, double click for rainfall |
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June
June was a very wet month, with torrential downpours and flooding in some regions. Northern and eastern England received more than 3 times the expected monthly rainfall, and experienced its wettest June on record (to 1914). Some areas of Yorkshire had 4 times the normal amount of rain. England, Wales and Northern Ireland all received more than double their long-term average rainfall. The region that was relatively the driest in June was northern Scotland, which received less than 80% of its average rain. Over the last 3 months, all regions have been wetter than average, particularly eastern England and the Midlands, and less so in northern and western Scotland and Northern Ireland.
As last month, mean regional temperatures, although above the 1961-1990 average in all regions, were closer to this
average than has been the case in most recent months. The mean temperature in Eastern Scotland was only 0.4°C above the long-term average. Three month mean temperatures are 1.5°C or more above the climatic average in all regions.
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Sheep Nematodes
Nematodirus
Warm and wet summers are generally associated with a greater prevalence of clinical parasitic gastroenteritis, allowing larvae to develop and migrate onto herbage. The peak of pasture infective larval numbers usually occurs from mid-summer. At the time of writing (early July), clinical PGE is a problem in many areas, and if July continues to be a wet month, disease prevalence this year could be high. In contrast, problems with autumn and winter PGE (following the arrival of autumn rains) may be fewer this year, as is often the case following wet summers, unless poorly controlled clinical PGE has led to very highly contaminated pastures.
If lambs are weaned and moved to safe pastures, group mean faecal egg counts will help to decide whether to treat with anthelmintic, bearing in mind that some lambs should be left undosed (perhaps around 10%) to carry some anthelmintic susceptible worms onto the new pasture. After the move, these lambs may not need to be treated for some time. This will depend on many factors including the amount of infection carried over, the stocking rate and the weather conditions. Faecal egg counts (FEC’s) are a useful guide.
Where weaned lambs must remain on contaminated pasture, FEC results are perhaps already being used to judge when suppressive anthelmintic treatment of the lambs should be given. Lower treatment thresholds will need to be used when using FEC’s for this purpose (limiting pasture contamination) rather than for avoiding clinical disease. The decision to treat in suppressive regimes is often made at a mean count of around 300 eggs per gram, but must also take into account other factors including stocking density and the genera of worms likely to be present, which can be investigated through the season by faecal larval culture or post mortem examination.
Underdosing lambs will lead to poor drug efficacy and will select for resistance. Clients should be reminded that drug dosages should be calculated for the heaviest in the group, not the average. Similarly, the importance of calibrating dosing equipment and correct dosing technique (over the tongue and not into the mouth) should be emphasised.
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Cattle nematodes
August often sees a significant level of clinical lungworm disease. Prevalence was low last year due to the dry conditions but continuing wet conditions will lead to a higher risk this year. The pattern of rainfall is also important. Heavy downpours break up faecal pats, aid the distribution of infective larvae on the pasture, and increase the risk of disease.
The epidemiology of lungworm is unpredictable, and safe grazing strategies are rarely successful. Unvaccinated grazing cattle will be at risk of disease if they are naïve e.g. in their first grazing season, in their second grazing season if given long acting suppressive anthelmintic treatment last summer, or adults which have not built up immunity through natural challenge in previous years.
If ostertagiasis is being controlled by a dose and move strategy, the original pastures will be potentially infective if youngstock are moved onto them later in the season. This may lead to inhibited larvae overwintering in the animals, and type 2 ostertagiasis in the late winter/spring.
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Liver Fluke Forecast
- Winter infection of snails
Summer infection of snails
June rainfall is often a good guide to the prevalence of fluke the following autumn, and indicates that this may be a high-risk year. Calculated Mt values that take into account the amount and temporal distribution of rainfall and the level of evaporation give a more accurate forecast of the potential for fluke disease, and a preliminary forecast will be produced next month and updated after the August figures are collected. The figures for the months so far suggest that there could be a high incidence of acute fluke this autumn given continued favourable conditions.
Winter infection of snails
Most snails infected over the winter will have died by the end of June. The wet May and June mean that most will have
passed infection onto the herbage before this. Last year’s dry summer and the dry April this year may have limited the number of infected snails overwintering, however conditions last autumn and this May/June have been ideal for fluke development. The Mt forecast for the winter infection indicates occasional losses from acute fascioliasis during the normally low incidence months from July to October in most regions of the UK, other than in southern and south-eastern England. Prevalence may be higher in western Scotland and to a lesser extent north-western England and North Wales. Stock on high-risk pastures on farms with a recognised fluke problem may require an early treatment this year.
Typical fluke and snail habitat with clumps of reeds – however, during wet summers favourable conditions for snail and fluke development can be spread widely over more normal field habitats.back to top |
Coccidiosis
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