Choose strategy with care to keep control
Choose strategy with care to keep control
Liver fluke appears to be
re-emerging as a disease of
sheep and cattle. But what
can be done to control it?
Veterinary Lab Agency
parasitologist Mike Taylor
looks at the options
FLUKE has reportedly been on the rise again over the past few years, presenting problems for both sheep and cattle farmers. Fasciola hepatica is a parasite of grazing animals, causing disease and production loss.
Incidence of liver fluke is greatly influenced by the weather, particularly rain during May to October, so it is more common in the wetter west of Britain. The crucial rainfall periods are late spring (May and June) when many fluke eggs hatch and snails multiply, and early autumn (September/October) when cercariae develop and are released on wet pastures before encysting on to herbage.
Snails – the intermediate hosts for motile fluke larvae (miracidia) – can either be infected in the summer or in autumn/winter. In wet summers, snail populations multiply rapidly and are invaded by hatching miracidia from May to July. If wet weather continues, snails shed massive numbers of mobile cercariae on to pasture during August-October which then encyst on grass to become metacercariae, which can remain infective for up to 10 months.
The profound influence that climate has on the life cycle explains the diseases variable nature and, in particular, why some years are bad fluke years. Over the past two years, for example, there have been increasing reports of fluke infections in cattle and sheep relating to the wet summers and milder winters. Although levels of infection are nothing like those seen in the 1960s there does appear to be an upward trend, and heavy rainfall over the past few months may see further rises.
The symptoms of liver fluke vary according to the levels of infection. In cattle with low infection rates there may be no obvious clinical signs although there may be weight loss and reduced milk yield and more heavily infected animals may exhibit bottle jaw – fluid under the jaw, diarrhoea and occasionally anaemia.
In sheep heavy infections can result in sudden death, but more generally there is loss of condition, anaemia – pale mucous membranes in the eyes and gums – and a tender, possibly fluid-filled abdomen. Bottle-jaw may also be seen in chronic infections. Liver fluke may predispose sheep to Black Disease and bacillary haemaglobinurea (Clostridial infections), and cattle to infection with Salmonella dublin.
Fluke control must take into account the farm type and its location – if there are suitable snail habitats – as well as the prevailing weather. Generalised fluke forecasts are available that take into account regional weather and forecasts.
Farms on free-draining soils or in low rainfall areas are not prone to liver fluke, but local conditions may vary enough to provide suitable snail habitats. Where fluke is present on a farm, identifying and excluding snail habitats offers some control, although it can be difficult to identify all snail areas and is costly to isolate them from stock. Drainage eliminates the snail and is effective, but may not be feasible in environmentally-sensitive areas. Simply keeping stock off the wettest fields in autumn and winter, when the disease is at its highest – between August and February – can cut fluke risk.
Treatment and control in cattle and sheep may ultimately rely on flukicidal drugs (see table). These may be specific products (eg, Fasinex, Flukanol), combination products (Combinex, Supaverm, Nilzan, etc), or routine wormers used at a higher fluke and worm dose rate (Albex, Endospec, Hapadex, etc).
A recent survey for England and Wales suggested some misconceptions on the activities of some of the available wormers. When in doubt consult a vet.
In normal rainfall years sheep should be treated in October, then January and May of the following year. It is important with sheep in areas where fluke is common to use a drug such as triclabendazole, which is active against both immature and mature flukes. In cattle at least one dose should be given in December or January.
In above average rainfall years, or in years with predicted above average incidence of fluke, sheep should be given extra doses in November and June, again using a drug active against immature stages; out-wintered cattle should be given an extra dose in April/May.
The VLA has produced an advisory leaflet available by phoning 01932-357314. On e-mail contact enquiries@vla.maff.gsi.gov.uk *
Healthy stock – but watch out because fluke is on the rise. Choose treatment and control products carefully.
Flukicide products for cattle and sheep
Cattle
Product name Company name Chemical name Parasites controlled Use
Albenil SC Virbac Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Albenil Low Dose Virbac Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Albex 2.5% SC Channelle AH Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Albex 10% SC Channelle AH Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Allverm 15% Crown Veterinary Pharmaceuticals Ricobendazole (Albendazole oxide) Roundworm, lungworm, tapeworm, fluke Oral drench
Endospec 10% SC Bimeda UK Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Endospec 2.5% SC Bimeda UK Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Fasinex 10% Novartis AH UK Triclabendazole Fluke Oral drench
Hapadex Cattle Wormer Schering-Plough AH Netobimin Roundworm, lungworm, tapeworm, fluke Oral drench
Levafas Fluke and Worm Drench Norbrook Labs (GB) Oxyclozanide Levamisole Roundworm, lungworm, fluke Oral drench
Ivomec Super Injection for Cattle Merial AH Clorsulon Ivermectin Roundworm Lungworm Fluke Ectoparasites Injection
Nilzan Drench Super Schering-Plough AH Oxyclozanide Levamisole Roundworm, lungworm, fluke Oral drench
Nilzan Gold Schering-Plough AH Oxyclozanide Levamisole Roundworm, lungworm, fluke Oral drench
Rycoben Cattle Youngs AH Ricobendazole (Albendazole Oxide) Roundworm, lungworm, tapeworm, fluke Oral drench
Systamex Plus Fluke SC Schering-Plough AH Oxyclozanide Oxfendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Trodax 34% Merial AH Nitroxynil Fluke Injection
Valbazen 10% Total Spectrum Wormer Pfizer Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Wormaway Albendazole 2.5% SC Diversey Lever Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Sheep
Product name Company name Chemical name Parasites controlled Use
Albenil SC Virbac Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Albenil Low Dose Virbac Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Albex 2.5% SC Channelle AH Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Albex 10% SC Channelle AH Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Allverm 4% Crown Veterinary Pharmaceuticals Ricobendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Combinex Sheep Novartis AH UK Triclabendazole Levamisole Roundworm, lungworm, fluke Oral drench
Endospec 10% SC Bimeda UK Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Endospec 2.5% SC Bimeda UK Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Fasinex 5% Novartis AH UK Triclabendazole Fluke Oral drench
Flukiver Janssen AH Closantel Roundworm, fluke, ectoparasites Oral drench
Flukol Youngs AH Closantel Roundworm, fluke, ectoparasites Oral drench
Hapadex Sheep Wormer Schering-Plough AH Netobimin Roundworm, lungworm, tapeworm, fluke Oral drench
Levafas Diamond Norbrook Labs (GB) Oxyclozanide Levamisole Roundworm, lungworm, fluke Oral drench
Levafas Fluke and Worm Drench Norbrook Labs (GB) Oxyclozanide Levamisole Roundworm, lungworm, fluke Oral drench
Mebadown Super Janssen AH Closantel Mebendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Nilzan Drench Super Schering-Plough AH Oxyclozanide Levamisole Roundworm, lungworm, fluke Oral drench
Nilzan Gold Schering-Plough AH Oxyclozanide Levamisole Roundworm, lungworm, fluke Oral drench
Rycoben SC for Sheep Youngs AH Ricobendazole (Albendazole Oxide) Roundworm, lungworm, tapeworm, fluke Oral drench
Supaverm Janssen AH Closantel Mebendazole Roundworm, lungworm, tapeworm, fluke Oral suspension
Systamex Plus Fluke SC Schering-Plough AH Oxyclozanide Oxfendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Trodax 34% Merial AH Nitroxynil Fluke Injection
Valbazen 2.5% SC Total Spectrum Wormer Pfizer Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench
Wormaway Albendazole 2.5% SC Diversey Lever Albendazole Roundworm, lungworm, tapeworm, fluke Oral drench