A herd of 41 pigs in the Mekong Delta province's Duc Hoa District began to die earlier this month. They were later determined to be infected with the African swine fever, said Dinh Thi Phuong Khanh, deputy head of the Long An Department of Agriculture and Rural Development. The remaining pigs in the herd were killed.

Duc Hoa is adjacent to Cambodia and HCMC and other infected areas, so it was difficult to prevent the swine fever from entering the province, the department said.

The African swine fever has also infected the delta's Can Tho City and 10 other provinces, leaving Ben Tre Province the only place uninfected in the country's food basket.

The disease reached Saigon last week, infecting a pig farm in the outlying District 9. More than 160 pigs at the farm have been culled, officials said.

59 out of 63 provinces and localities of Vietnam have so far been infected with the disease. The country has culled at least 2.45 million pigs since the disease was first discovered in the northern region in early February.

The country is estimated to have lost VND3.6 trillion ($154 million) from the disease so far, with the costs including fees for culling infected pigs and spraying of affected areas wth disinfectants.

Vietnam has the seventh largest number of pigs in the world, 30 million, and is the sixth largest pork producer. Pig farming provides a livelihood to 2.4 million households, according to official figures.

Pork makes up 70 percent of the average Vietnamese diet. The Ministry of Industry and Trade is looking at frozen pork supplies as a plan to meet a possible pork shortage. The Ministry of Agriculture and Rural Development has warned people not to continue raising pigs, and to raise other animal groups like buffalos, cows, poultry or seafood instead.

The epidemic’s discovery in Vietnam coincided with a spike in pork imports, which rose 6.7 times in the first four months this year from the same period last year to $23.58 million.

African swine fever is an incurable disease with a 100 percent mortality rate for pigs, but does not affect humans. The virus is shed in blood, saliva, tears, nasal secretions, urine, faeces, and secretions from the animal's genital tract.

Latest data collected by June 6 from the World Organization for Animal Health shows 13 countries and territories are suffering from new or ongoing outbreaks of the disease: Belgium, Hungary, Latvia, Moldova, Poland, Romania, Russia, Ukraine, mainland China, Hong Kong, North Korea, Vietnam and South Africa.