Leptospirosis is an infectious disease transmitted from animals to humans. Despite widespread vaccination of dairy herds, there are still around 100 reported human cases a year in New Zealand, and it is estimated that the numbers of unreported or undiagnosed cases are actually 40 – 50 times higher.
Farmers and other occupations involving animal contact represent the bulk of the infections. Symptoms of lepto in people can be particualry nasty and may include:
- severe and persistent headaches
- high temperature and chills/sweating
- muscle pain (myalgia), particularly in the lower back and calves
- abdominal pain
- nausea and/or vomiting
- diarrhoea
- loss of appetite
Most people who are severely affected find it physically impossible to return to work within the first two months and it can take a long time to regain the energy that they had before becoming ill.
The continued high levels of human infection are likely due to incorrect vaccination programmes, stock movement without vaccination, and sheep and beef farms acting as reservoirs. Leptospirosis is tough to eliminate therefore a robust vaccination programme is essential to break the cycle of infection. Exposure is minimized using a comprehensive rodent control programme, practicing good personal hygiene and wearing appropriate protective clothing.
The main lepto serovars infecting livestock in NZ are L. hardjo and L. pomona. In NZ serovars Tarrasovi, Hardjobovis, Pomona and Ballum are currently those most commonly identified with disease in humans whilst Hardjobovis and Pomona are most significant in livestock.
VACCINATION
The ideal conditions for survival and transmission of leptospires are warm and wet climatic conditions. Annual revaccination can be timed to be just prior to this period of greatest risk. This will vary by region in NZ and by season, but annual revaccination in late summer/early autumn is generally recommended.
CALVES
Vaccinate early from 4 – 6 weeks of age before the calf has a chance to become infected.
YEARLINGS
Need to be vaccinated at the same time as the breeding herd to maintain protection from their calf vaccinations.
BREEDING COWS
Annual revaccination aims to protect the cow from infertility and abortion related to leptospirosis, and protect her unborn calf from becoming infected in utero. Newborn calves will also be protected via maternal antibodies.
BULLS AND ANY OTHER BOUGHT IN STOCK
Must be sourced from herds that have an up to date vaccination programme.
Zoetis vaccines are clinically proven to protect against leptospirosis and prevent:
- Renal colonisation and urinary shedding
- Reproduction tract colonisation and shedding
- Infertility and foetal infection with L. hardjo
Traditionally calves have been vaccinated at 6 months of age however, research shows that calves can be exposed and infected naturally before 6 months. Vaccination programs rely on passive immunity to protect calves until vaccinated. However, recent studies suggest that 80% of calves have no MDA by 7 weeks.
Latest New Zealand research shows that vaccinating your calves at a young age is a key first step for field to family protection. Our leptospirosis best practice recommendation aligns with industry best practice.
Zoetis Field to Family Best Practice Recommendation – calves need to be vaccinated 10 weeks from the planned start of calving.
- PSC - Planned Start of Calving
- Assumes a 6 week calving spread*
- Option: Vaccinate in batches if the calving spread is logn.
Leptoshield, Leptoshield 3 and Ultravac 7in1 vaccines offer immunity against Leptospirosis for at least 12 months, have a 30 day broached vial shelf life and ability to vaccinate from 4 weeks.
CONTROLLING LEPTOSPIROSIS
Vaccination is the key to prevent leptospirosis in livestock. If any of the following apply to you then your farm is high risk:
- Autumn calving
- High spring / summer rainfall
- Surface water or flooding
- Cross boundary water ways
- Contact with unvaccinated cattle, sheep, pigs and deer
- Off farm grazing
- Uncontrolled rodent populations
For more information contact your vet.
'Approximately 100% of New Zealand sheep and beef farms are shown to have been infected by Leptospirosis'
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