Leptospirosis infection in sheep could be a bigger issue than most farmers realise according to research by Massey University, which highlights the disease’s prevalence in NZ sheep flocks.

Zoetis veterinary advisor Dr Victoria Chapman.

Researchers found 97 per cent of sheep properties had evidence of infection with either of the main strains: L hardjobovis or L Pomona.

“Typically leptospirosis has flown under the radar for sheep farmers,” says Zoetis veterinary advisor Dr Victoria Chapman.

“Dairy farmers are familiar with its impact both on animal and human health, but there has been a real lack of data until now on just what its prevalence and impact is here in NZ sheep flocks,” says Victoria.

“At any one time there may be 10-20 per cent of the country’s sheep population shedding infectious leptospires.”

Victoria says these levels of infection are a wake-up call to the industry.

“Infection from leptospirosis could be contributing to unexplained lamb losses or abortions in ewes.”

She urges farmers to consider potential risk factors of their farm and unexplained flock health problems that could be caused by leptospirosis infection.

“If the farm is located in a particularly wet area, then that is higher risk. Leptospires thrive in those conditions and lamb losses of up to 15 per cent from leptospirosis infection have been experienced in wet conditions.”

Farms with bush boundaries could also be more susceptible, with wild pig and possum populations also being infection carriers.

“Of course there is how you, as a farmer, view the human health risk of leptospirosis. Ask anyone who has had it, and they would never wish it on friends, family, staff or contractors; and would recommend vaccination to avoid that risk.”

The avoidance of WorkSafe liability will be a major factor for many farmers in deciding to vaccinate, especially those on corporate farms, sheep dairy operations and regional parks.

There is now further information available as Zoetis has recently completed a clinical trial evaluating vaccine efficacy and the protection provided to sheep against leptospirosis.

Ultravac 7 in 1 vaccine is found to be highly effective in controlling leptospirosis in the trial flock, recording 100 per cent efficacy in vaccinated animals.

This work is the first significant study in 25 years on efficacy of leptospirosis vaccines in sheep.

“It is reassuring to know we have vaccines available that can work effectively against a fairly insidious disease,” says Victoria.

“It’s a disease that also brings some human health risk for staff, contractors and meat processors, who may come in contact with infected stock – and for some farmers vaccination maybe worth considering.”

Victoria urges farmers to sit down with their veterinarians when having annual animal health programmes assessed to get professional advice on leptospirosis risks relative to their farm’s unique factors.

“This is a disease we now know is widespread in relation to sheep infection; we know the risks involved and with appropriate guidance from a vet, an effective vaccination programme can be implemented if needed.”