Wednesday, 29 October 2014 08:49

Treat now to fight Theileria – vet

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FARMERS could safeguard next year’s calves against Theileria by treating cows for ticks in summer according to senior Vets North vet Mark Anderson.

 Anderson recently told 60 farmers at a Beef + Lamb NZ event at Tomarata, near Wellsford, that while little was known about the potentially disastrous condition there could be a way to combat it.

A tick-borne disease caused by an intracellular blood parasite, Theileria can result in anaemia, lethargy, lack of appetite and can cause a drop in milk production, rising somatic cells and even death for cows and calves in extreme cases.

As the parasite can only travel from host to host through tick bites Anderson says this has limited the spread of the disease to farms in Waikato (a moderate infestation in Reporoa), Whanganui and Eketahuna.

While the disease has been spreading rapidly across these regions over the last 12 months, to the point where animal health professionals now suspect every herd in Northland has the disease, Anderson expects it to stay in the area it has infected and only pose a serious risk to stock not exposed to it before.

“The two classes of animal that will get sick and could die from Theileria are cows that have been shipped into the area that haven’t been exposed to it and calves going onto grass for the first time. The rest of your herd probably have the disease and it doesn’t bother them.”

While buying replacements from local sources is relatively easy, Anderson says protecting calves from Theileria can take a little more planning, especially as it takes very little for the parasite to spread. “It just takes a bite from an infected tick and all your calves have got it.”

While nothing can be done to treat the parasite when animals have it, Anderson believes farmers could prevent young stock contracting it when they are at their weakest with the use of a pour-on drench.

The parasite is believed to pass from cow to tick and back to cow as the tick can’t pass on the parasite itself through genetics or in its eggs, Anderson says. This means farmers could kill the ticks with the parasites before stock have the chance to pick up the parasite.

Ticks emerge as larvae in January-February, maturing and becoming adults in November-January.

The critical times for dairy farmers are December, when ticks bite cows with the protozoa parasite, and again in July-August when calves go from the calf shed to the pasture for the first time. “It only takes one tick with the parasite to infect your calves but if you can kill all the ticks with the virus then any that bite calves won’t be able to pass Theileria on.”

He says the pour-on Bayticol works to kill ticks successfully while also not having any withholding period for either milk or meat.”

As ticks contract the parasite by biting infected cows, Anderson says drenching the main herd now should mean that ticks bite calves free of Theileria because they haven’t had chance to bite cows yet.

No Risk to Humans - Theileria Facts

Theileriosis only affects cattle and is transmitted by cattle ticks

Theileriosis causes anaemia in cattle and can sometimes be fatal

Cows during calving and young calves (2-3 months) are at most risk from infection

There are no human health or food safety risks associated with Theileriosis.



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