African swine fever poses little threat to NZ - MPI

The Ministry for Primary Industries says African swine fever probably won't reach here, despite an outbreak in Asia.

Millions of pigs have been slaughtered in Vietnam, and it's feared the disease could travel here through tourists.

But MPI spokesperson Dr Chris Rodwell says tourists can only bring in highly processed meats.

"Although this is a really nasty disease for pigs, it's actually got to get into the country - so somebody imports high-value pork products - then they're going to eat those products generally, they're not going to feed them to pigs."

African swine fever doesn't cause disease in humans, but is devastating to pigs.

"In its acute, and most common, form the pigs can experience high fevers, loss of appetite, internal bleeding, bloody diarrhoea and vomiting, coughing and laboured breathing - and after one to two weeks it's basically unsurvivable," Freedom Farms manager Hilary Pearson wrote in a piece for the Spinoff last week.

"A nightmare scenario is believed to have played out in Belgium, where pigs were infected after a traveller discarded a ham sandwich, containing ham from an infected pig, on the roadside, and it was found and eaten by a roaming pig, starting an outbreak that has almost ruined their local pork industry."

Dr Rodwell says a quarantine process would be carried out if the swine fever did arrive here.

"If we were to get a situation where we did have an incursion of disease, then we've got a very very strong surveillance system post-border that picks up anything nice and early."

Dr Rodwell says visitors with meat are also questioned at the border.

"If people are caught smuggling material in... then they will be dealt with by the full force of the law, and rightly so."

Belgium has been slaughtering pigs and wild boar since the breakout.