Last Saturday, the central province's sub-department of livestock production and animal health said the incurable disease that afflicts pigs but not humans was detected at a farm in Ninh Son District.

After 354 pigs at this farm died abnormally, tests showed that they were infected with African swine fever.

Veterinary officials said all the infected pigs have been killed and measures taken to minimize the spread of the disease.

Areas near the location of the outbreak have been sanitized while checkpoints would be set up to prevent delivery of more infected pigs, they said.

African swine fever first hit the country early February and quickly spread across the northern and central regions before reaching the south in early May.

Vietnam has so far culled 13 percent of its pig stock, or four million pigs, according to the Ministry of Agriculture and Rural Development.

The disease’s virus is shed in blood, saliva, tears, nasal secretions, urine, feces, and secretions from the animal's genital tract. Pigs can thus get the infection by contact with many different infected sources, mainly other infected pigs, pork and other pig-derived products but also any other contaminated objects, according to the Food and Agriculture Organization.

Pork makes up three-quarters of total meat consumption in Vietnam, a country of 95 million people where most of its farm-raised pigs are consumed domestically.

The country’s pork industry is valued at VND94 trillion ($4 billion), and accounts for nearly 10 percent of Vietnam's agricultural sector.

African swine fever was first detected in Asia last year in China, the world’s largest pork producer. As many as half of China’s breeding pigs have died or been slaughtered because of the disease, twice as many as officially reported.

Data from the World Organization for Animal Health shows that as of August 29, 19 countries and territories have notified new or ongoing outbreaks: Belgium, Bulgaria, Hungary, Latvia, Moldova, Poland, Romania, Russia, Serbia, Slovakia and Ukraine in Europe, China, North Korea, Laos, Myanmar, Russia, and Vietnam in Asia, and Africa's Zimbabwe and South Africa.

The Vietnam National University of Agriculture started researching a vaccine for the disease in March this year. Thus far, it has developed four kinds of vaccines, one of which has shown good results among 13 out of 14 pigs tested, it said at a meeting last July.