The provincial veterinarian office on Thursday said the death of at least 50 pigs here since December was caused by a mixture of viral and bacterial infection.

But Dr. Nestor Barroga, provincial veterinarian, said they could not determine yet what type of virus affected the animals.

Barroga's statement came in the wake of the tests being conducted by experts from the United Nations on pigs in Luzon, where a strain of the Ebola-Reston virus was found last year.

Barroga said they were trying to immediately determine the type of the virus that downed pigs in at least eight villages here and that more samples have been brought to the regional animal center in Davao City for testing.

While veterinary officials wait for the results of the tests, animals here were still being quarantined.

Barroga said pig pens where animals have died had also been disinfected.

Renato Enanoria, regional quarantine officer, said the decision to quarantine animals here was arrived at as the type of the virus that helped down the pigs had yet to be established.

In the village of Pong-pong here, where most of the animals mysteriously died, residents said the incident could lead to the loss of their livelihood.

Ranilo Tiwi, a hog raiser here, told the Philippine Daily Inquirer, he already lost nine hogs since the mysterious disease started to affect animals in December.

Mercy Olalo, another hog raiser, said their animals would suddenly become weak and eventually die.

"The pigs developed red skins and they salivate excessively," she said.

Tiwi said alarmed residents immediately disposed of their animals but buyers have since returned the hogs.

"They died as soon as they were returned," he said.

Tiwi said some of their neighbors have slaughtered their weak animals and either sold or consume the meat.

"In fact they have slaughtered it for fear that it will die," he said.

Justin Masaganda, municipal agriculturist, said they responded as soon as they got information that hogs were dying in the town despite being holiday.

Masaganda said they also advised residents against slaughtering the animals pending the outcome of the test conducted by veterinary officials.

Asked whether the hogs died of cholera, which has also affected some areas of Mindanao in the past, Masaganda said they have yet to determine it but that it was among their suspicions.

Antonio Lavega, municipal livestock coordinator, said they already told residents to bury the dead animals after testing to prevent more problems.

He said they were not saying that the disease killing the animals was communicable but that it was better to be careful.