Science & Environment

EU worries over pig virus prompt new blood import rules

pig Image copyright Getty Images
Image caption Young pig are particularly susceptible to PEDv

The EU Commission has agreed new rules to limit the spread of a deadly swine disease that has killed millions of piglets in the US.

Porcine Epidemic Diarrhoea virus (PEDv) has wiped out around 10% of the American herd in a year.

While the EU rejected an outright ban on live pig imports, it has restricted blood products used in pig feed.

However a Canadian minister said measures were "disappointing" and not based on science.

While the virus isn't harmful to humans or food, concern has grown in Europe over its potential economic impact

PEDv is spread in faecal matter and attacks the guts of pigs, preventing them from absorbing liquids and nutrients.

Older animals can survive, but fatality rates among piglets run between 80% and 100%.

Deadly spoon

So virulent is the agent that one expert estimated that a spoonful of infected manure would be enough to sicken the entire US herd.

France announced last week that it was set to suspend imports of live pigs and sperm from the US, Canada, Japan and Mexico.

However the French delayed their ban to allow the EU Commission to consider a pan-Union response.

At a meeting in Brussels, experts from member states reviewed the most recent scientific information on PEDv and decided against a ban on imports of live pigs.

They argued that live imports aren't a major problem, with around 250 animals being brought in from Canada and the US last year. No live consignments are scheduled to be sent to Europe at present.

EU officials did toughen up the rules on the imports of blood products from countries where the virus is active.

Spray dried pig plasma is used in feedstuffs that are given to weaned piglets.

Earlier this year, Canadian researchers said that they had found the infective agent in dried blood imported from the US. Europe imports about two tonnes of pig blood for feeding purposes every year.

"The feed is suspected," said Dr Bernard Vallat from the World Organisation for Animal Health (OIE).

"Blood from slaughterhouses with insufficient heat treatment is suspected to be the origin. We don't have a scientific publication on that but it is highly suspected," he said.

Rising temperatures

The new EU rules stipulate that these products can now only be imported after they have been heat treated to 80 degrees C.

The products must then be stored for six weeks to kill any virus that might have contaminated the blood after the treatment.

However the Canadian agriculture minister Gerry Ritz said the EU move was "disappointing".

According to agency reports, the minister said the new restrictions weren't based on science.

The virus is believed to have its origins in China.

In North America, the disease has moved rapidly, with around 4,000 outbreaks in 30 US states, in four Canadian provinces and in parts of Mexico.

Experts in the field believe that lax biosecurity is an important factor.

In June last year, a US study found that 17% of trucks going into a slaughterhouse were positive for the infection.

"They also discovered that 11% of the trucks that had been negative when they went into the slaughterhouse were subsequently positive when they left," said Dr Zoe Davies from the UK's National Pig Association (NPA).

"It's how many animals you are moving around, that's how its being spread."

Image copyright Getty Images
Image caption China has seen a number of outbreaks of deadly pig diseases in recent years and it is believed that PEDv originated there

In the UK, the NPA says it has already secured support from all major importers to restrict pigs from infected countries. It says that more than 92% of pigs reared in the UK are not fed on blood products.

PEDv was first diagnosed in the UK in 1971 but that strain was a milder form and pigs quickly adapted to it and became immune.

However, the fact that European pigs have a history of exposure to a related virus may give some hope of protection, according to Dr Vallat.

"It circulated before in Europe but it was a different strain. If there is some remaining circulating virus there is a possibility that animals would be protected - but it is not sure."

This perspective though is challenged by Dr Zoe Davies, who says that Europe is now highly vulnerable to the infection.

"Everyone seems to think that because we've had versions of PEDv in the past we will have some immunity to this new strain and we know categorically that this is not the case."

"We've tested our own herds and we think around 10% of the animals have antibodies to the older strains, we are effectively a naive herd, which is why we are worried."

In the US, pig prices have risen considerably as a result of the losses to the virus while demand for pork shows no sign of abating. According to pig producers in the US, the industry is in for a strong financial year.

"One of the consequences of the problem, the restriction of the products in the market, mean perhaps prices could grow," said Dr Vallat.

"For the non-infected herds it is good news."

Follow Matt on Twitter @mattmcgrathbbc.

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