The NADIS disease forecast is based on detailed Met Office data, and regional veterinary reports from 37 farm animal practices and the large animal units at six UK veterinary colleges.

NADIS data can highlight potential livestock disease and parasite incidences before they peak, providing a valuable early warning for the month ahead.

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.

April 2005

Richard Laven PhD BVetMed MRCVS

 
 

Listeriosis

The bacterium Listeria monocytogenes, which causes listeriosis, is one of the most important causes of infectious disease in cattle. The bacterium is found throughout the environment and in decaying plant material. Soil contamination, either of pasture or, more commonly, preserved forage, especially silage, is the main source of the bacteria which cause listeriosis.
Infection by Listeria is associated with three syndromes in cattle: abortion, eye infection (silage eye) and brain disease. The latter is the disease most commonly referred to as listeriosis.

Disease Signs
• Loss of appetite and depression
• Nervous signs usually show first as disorientation followed by leaning, standing in corners or circling
• Paralysis of one side of the face leads to a dropping ear, muzzle, eyelid and lip.


                   

• Swallowing may becomes with excess saliva being produced and food becoming impacted.
• As the disease develops the inco-ordination increases and the animal may collapse.
• Death occurs in around 50% of untreated cases.


Diagnosis
• Clinical signs are very helpful but collection of spinal fluid may be useful in some cases.
• Post-mortem examination of cases which die is usually very helpful
• If abortion occurs then sending the calf and membranes to the lab is very valuable also

Treatment
• Give antibiotics as soon as possible and treat until the signs are no longer present
• A wide variety of antibiotics have been used to treat listeriosis, ask your vet for advice as to which would be the best for you to use.
• If a specific source can be identified, such as spoiled silage, remove it as soon as possible
 
Prevention
The bacterium is present in the soil so the best method of prevention is to reduce soil contamination.
a) Avoid work such as hedge trimming in field with stock if this will create soil disturbance
b) Minimise the amount of soil contamination when cutting forage for preservation
The next major control point is the forage preservation process. Listeria cannot grow at a low pH, so well controlled fermentation should significantly reduce the risk of disease. This is particularly important for big bale silage as the pH of this is usually higher than clamp silage.

Copyright © NADIS 2005


While every effort is made to ensure that the content of this forecast is accurate at the time of publication, NADIS cannot accept responsibility for errors or omissions. All information is general and will need to be adapted in the light of individual farm circumstances in consultation with your veterinary surgeon

 


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