TOKYO (BLOOMBERG) - A simple package of sausages shows how the outbreak of African swine fever in China is roiling meat producers and markets in Asia.

About 1.5kg of sausage infected with the virus was discovered in the luggage of a Chinese tourist at an airport in Hokkaido early this month.

That prompted Japan's Agriculture Ministry this week to warn farmers and anyone involved in the industry against overseas travel, as well as impose stricter quarantine measures across the nation.

While African swine fever isn't harmful to humans, it is fatal to pigs - and is incurable.

Its spread through China since July has the potential to devastate China's US$128 billion (S$176 billion) pork industry. And it has countries throughout the region scrambling to protect their own hogs.

In Japan, that means the famed tonkatsu (fried pork cutlet) and almost every bowl of ramen are at risk.

Pork meat is a problem because the virus can survive for more than a year in products such as dry cured ham.

If any offcuts of infected pig meat find their way into a swine's feed, it is essentially game over for that pig and any others that come in contact with it.

That has already prompted the United Nation's Food and Agriculture Organisation to say the disease's spread in Asia is a near certainty. Japan's response may just be the first of many.