LEPTOSPIROSIS

Signs

What is Leptospirosis?

Leptospirosis is a bacterial disease that has many strains and can affect many species of mammals. The strains are called serovars. The serovar most commonly affecting cattle in our area is called Hardjo.

What are the signs of Leptospirosis?

The signs of leptospirosis depend upon the age and immune status of the animal and the serovar causing the infection.

L.hardjo (signs may include)

  • Loss of milk production in all quarters without the usual signs of mastitis; udder is soft, flabby and free of pain - production usually returns to normal within 14 days.
  • Loss of appetite and mobility in severe cases.
  • Abortion, stillbirths or the birth of live, sickly calves.
  • Infertility
L.hardjo may affect cattle of all ages but the clinical signs are usually only seen in pregnant or lactating animals.

L.pomona produces disease in calves and adult cattle with signs as follows:

Calves
Jaundice
Anaemia
Haemoglobinuria ( red urine or redwater)
Fever
Death may occur

 

Adult cattle
As for calves
May show milder signs which include loss of milk production (milk may be discolored) and abortion.

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Spread

How is leptospirosis spread?

After clinical leptospirosis with Lepto Hardjo, infection localises in the kidney, Leptospira are then shed in the urine for a variable amount of time until the cow develops immunity to the disease. This can take up to 2 years. A small percentage of cows will continue shedding indefinitely. These cows, that are not showing signs of disease, but are shedding the bacteria, are called carriers.

Carrier cows will spread massive numbers of leptospira every time they urinate. The bacteria cannot withstand drying and will not last long in the environment. Therefore direct contact with infected urine as liquid or splashed into aerosol form is the main mode of transmission.

Leptospira will readily invade mucous membranes. The nose, mouth and eyes are particularly susceptible. Non-immune animals including humans are at risk of infection any time a carrier cow urinates nearby. The dairy is an ideal place for transmission.

As the number of carrier cows in the herd increases, so does the risk of infection to both humans and cows.

What are the symptoms of leptospirosis in humans?

Leptospirosis causes severe influenza-like symptoms that persist longer than a normal case of the flu. Symptoms include fever, headache, sore muscles and general malaise.

 


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Treatment and Prevention

Can leptospirosis be treated?

Leptospirosis is treated in both humans and animals with the appropriate antibiotics. Identification of carrier cows is difficult so that whole herd treatment would be the only way to eradicate leptospirosis from the herd using antibiotics.

In terms of economics, herd production, herd health and human health, prevention of infection is a more realistic approach.

How can I prevent leptospirosis?

There is no vaccination available for humans against leptospirosis. Therefore, it is doubly important to prevent infection in the herd.

A combined vaccine is available for cattle against Lepto Hardjo and Lepto Pomona. If a vaccination program is carried out, most previously susceptible animals will be rendered immune to the disease. These animals will not become symptomatic if exposed to the bacteria and will not become carriers.

Cows that are already carriers when the vaccination program is commenced will continue to shed bacteria until they develop a natural immunity to the disease. But vaccination decreases the number of leptospira shed in the urine.

In summary, the benefits of vaccination to human and herd health are:

  • The protection of calves from serious clinical leptospirosis.
  • The protection of cows from production limiting clinical leptospirosis.
  • The protection of the herd from reproductive losses caused by leptospirosis e.g abortion.
  • The protection of farming families by decreasing the number of carrier cows in the herd and the increasing number of leptospira they shed.
  • Visiting workers eg Milking staff, Vets, AI technicians etc.
Within 1-2 years of a continuing vaccination program, most carrier cows will become naturally immune and, with the prevention of new infections, leptospira will be virtually eliminated from the farm.

To prevent the re-introduction of lepto into your herd an on-going vaccination program for the herd is recommended.

 


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Vaccination Program

    Calves
  • Vaccinate at 8-12 weeks
  • Vaccinate again 4-6 weeks later
  • Annual booster required.

    First Year of a Vaccination Program for Cattle

  • Vaccinate all stock
  • Repeat vaccination 4-6 weeks later

    Subsequent Years of a Vaccination Program for Cattle

  • Annual vaccination of herd
  • Follow instructions above for calves
STORAGE OF VACCINE
  • Store at 2°C to 8°C (Refrigerate. Do not freeze)
  • Protect from light
CAUTION TO AVOID CARCASE DAMAGE
  1. Sterilise all injection apparatus by boiling in water for 10 minutes (or equivalent) before use. Avoid use of strong disinfectants on apparatus.
  2. Maintain cleanliness at all times during vaccination. Great care must be taken to avoid contamination of the vaccine, needle and internal parts of the syringe by contact with unsterile surfaces or unwashed hands.
  3. Keep needles sharp and clean. Replace frequently.
  4. Use the shortest possible needle, not exceeding 15mm in length.
  5. As far as possible avoid injection of animals during wet weather or under dusty conditions.
  6. This product must be injected only under the skin (subcutaneously).
  7. If possible inject high on the neck, behind the ear, i.e. under the skin on the side of the neck (just behind and below the base of the ear).
    Do not inject at any other site.
Unused vaccine may be held over for use the next day, provided instructions for resealing are followed.
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