NADIS disease bulletins are written specifically
for farmers, to increase awareness of prevalent conditions and promote
disease prevention and control, in order to benefit animal health and
welfare.
Farmers are advised
to discuss their individual farm circumstances with their veterinary surgeon. Liver fluke infection (Fasciolosis) The recent wet weather has increased the risk of
liver fluke in those areas where the parasite is found. This is likely to
result in an increase in the number of cases of liver fluke reported by
NADIS, but it is unlikely that the number of cases will be as high as 20 to
30 years ago What is
Liver Fluke The liver fluke is a flat leaf-like parasite found in the bile ducts of the
liver. The life cycle of the fluke is very complicated. A simplified version
is shown below.
1)
The adult liver fluke in the liver of the cow produces eggs which
pass onto the pasture. 2)
These eggs hatch in warm damp conditions to produce mobile larvae
which then infect one species of snail. 3)
The fluke develops in the snail until developing into another
swimming stage which settles on the pasture 4)
This then develops into a highly resistant non-mobile stage which once eaten by the cow hatches and
migrates to the liver The signs in the cow are
all due to liver damage, with the symptoms varying depending on number of
flukes present in the liver. The disease is commonest
in the wetter western areas of the UK and Ireland with the levels of
infection and disease being very dependent upon the rainfall from May to
October. Within the wet areas of the UK, the distribution is entirely
dependent upon the presence of the snail host. No snail, no fluke. Clinical
Signs In the UK liver fluke tends to be more severe in
sheep and goats can do considerable
harm to cattle. In cattle, liver fluke is normally a sub-acute or chronic
disease The principle signs are: ¨ Progressive weight loss ¨ Reduced milk yield Less common signs include: ¨ Bottle-jaw ¨ Abdominal swelling due to
accumulation of fluid (ascites) Diagnosis ·
On the clinical signs
described above ·
Faecal egg count, presence of any eggs is suspicious of fluke
infection ·
Your veterinarian can also do
blood tests which show the extent and severity of liver damage Treatment ·
A large number of anthelminthics are available for treating fluke in
cattle. As fluke tends to be chronic, most will be effective, but seek
veterinary advice if you have not
treated fluke before Prevention 1)
Where fluke is present, excluding cattle from typical snail habitats
(low lying we areas, margins of ponds) can reduce fluke infection but
complete snail avoidance is impossible as it is very difficult to identify
all snail sites 2)
Drainage eliminates the snail and offers an effective means of
control, indeed it is probably responsible for the large fall in cases of
fluke since the 1970’s. 3)
Chemical control has been used to reduce snail numbers but is no
longer available. 4)
Routine worming of cattle in December/January should control fluke in
average rainfall years. If the rainfall is heavy an additional dose for
out-wintered cattle may be required in May Copyright © NADIS 2002 NADIS is sponsored by Milk Development Council Elanco Animal Health Schering Plough Animal Health SUPPORTING
BRITISH DAIRY FARMERS |
