Philippines is culling 6500 hogs after Reston ebolavirus outbreak

Friday, March 6, 2009

Transmission electron micrograph of the Ebola virus.

The Philippine Department of Agriculture (DA), local health and agricultural teams Sunday have started slaughtering, burning and burying roughly 6,500 hogs at a farm in Pandi, Bulacan in Central Luzon on Sunday after three farm workers became infected with Reston ebolavirus (ERV) of the virus group Ebola, as a precautionary measure and to protect the local livestock industry.

"We culled around 300 heads—piglets and growers—in two and a half hours; we tried to start the process at 5 p.m. Sunday; after three hours we disposed of 442 hogs; that includes transporting the hogs to an area in the farm where they will be disposed of; with this rate and with some improvements in the procedure tomorrow, we expect to complete the depopulation by Wednesday,” Bureau of Animal Industry (BAI) head Davinio Catbagan said. "With the problems we encountered last night, we may go beyond Thursday," he added.

But according to Dr. Eric Tayag, the 56-man team's five captive bolts used in stunning the pigs malfunctioned, for which reason, they decided use instead .32 caliber pistols. "We need to finish this off because sometimes it rains," he said. But due to other problems, 12 policemen were ordered to use instead .22 caliber guns for 80-120 kilograms pigs. The pig depopulation in the Pandi farm has reached 1,237 Tuesday amid strong rains as schedules have been set from 5 a.m. to 9 a.m. and from 4 p.m. to 9 p.m. daily, Cecilia Yacob, head of the Bulacan Provincial Public Affairs Office, said.

Monday's culling was witnessed by representatives from the Food and Agricultural Organization (FAO), the World Health Organization (WHO), animal welfare observers, Bulacan Gov. Joselito Mendoza and Pandi Mayor Roberto Oca. The slaughter has been estimated to cost 16 million Philippine pesos (₱), which include hog farm owners' compensation and the cost of culling for five to seven days.

"As of late Tuesday the depopulation teams have culled 2,663 pigs, compared to 442 on Sunday, 795 on Monday and 1,426 on Tuesday; as of early afternoon on Wednesday, the numbers have reached 3,482," said Dr. Davinio Catbagan. According to Agriculture Secretary Arthur C. Yap, the culling team has slaughtered 2,078 pigs, bringing the total to 4,741 on Wednesday. The number of hogs had increased to 6,500 from 6,000 as some mother pigs gave birth amid the depopulation.

But according to Dr. Joy Gomez, provincial public health officer of Bulacan, six members of the depopulation team at the Pandi "Win Farm" have complained of fatigue, headache and dizziness, and have been closely observed by a team of doctors.

The state will compensate the farmers, however "it cannot be [100% of the market price.] A range of about 25%-50%, but it has to be discussed [with the farm owner]. At 25%-50%, the government may pay the farm owner ₱6.28 million-15.625 million, plus the cost of animal culling operations," said Yap.

A polymerase chain reaction test to check the virus' presence was conducted by the United States Centers for Disease Control (US-CDC) to verify ongoing transmission. "Of 160 pig blood samples that were positive for antibodies, 133 came from Bulacan and 27 from Pangasinan as reported by RITM. Those from Bulacan were traced to pigs at different age groups while those in Pangasinan were found in sows and just one piglet. This means that there is on going viral transmission in Bulacan but past infection with recovery was the case in Pangasinan,” Yap explained.

The agriculture officials earlier announced that the depopulation will be carried out in a "humane" manner, following current Office international des épizooties (OIE) procedures that ensure protection of animal welfare in the Bulacan farm. According to Philippine Department of Health (DOH) Secretary Francisco Duque, the quarantine of the hog farm in Palauig, Manaoag, Pangasinan has been lifted after finding no traces of viral transmission.

According to Yap, test results conducted by a joint mission of FAO, the World Animal Health Organization, WHO and their local counterparts, reveal that viral transmission continues to exist in Pandi hog farms, which is only 0.5% of the 13 million pigs raised throughout the country.

DOH officials also say a pig farm worker in Cabanatuan City in Nueva Ecija, who had no direct contact with sick hogs, has tested positive for Immunoglobulin G antibodies against the Reston ebolavirus, which is non-lethal, unlike the Zaïre, Bundibugyo, Côte d'Ivoire and Sudan strains, according to FAO.

"The additional positive human sample, showed signs of antibodies for Ebola Reston, was traced to a slaughterhouse male worker and was not sick during visits by the investigation team. He does not recall any direct contact with sick pigs but remembers having flu-like sickness in the past twelve months," a DOH statement said, also confirming four pig farm workers and a butcher from Bulacan and Pangasinan tested positive for the antibodies last month.

"Ebola Reston poses a low risk to human health at this time," said DOH Secretary Dr. Duque. "147 human samples have been tested for Ebola, but only six have tested positive. But stay away from kilawin, and half-cooked pork," he added. The laboratory tests of 147 blood samples from workers in the affected areas were conducted by the Research Institute for Tropical Medicine (RITM) and the US-CDC. RITM has also reported that "1039 pig blood samples collected by the expert mission yielded negative results on antigen tests," the DOH said.

The 24 other workers tested were all found negative for ERV infection. "To date, all close contacts of humans with positive anti-bodies who were tested remained anti-body-free signifying absence of illness in affected humans that can lead to possible human-to-human transmission," Dr. Duque said. The RITM and the US-CDC also tested 160 pig blood samples: 133 of which came from the Bulacan farm and 27 from the Pangasinan farm; of the 133 blood samples from Bulacan, 19 tested positive for ERV; none of 27 samples from Pangasinan were affected.

Map of Bulacan showing the location of Pandi

Global experts said they will continue to conduct research studies of the Ebola strain to determine how it can be controlled. FAO of the United Nations has initially committed ₱10 million to buy additional kits. "We support the Bureau of Animal Industry to expand surveillance in other areas," said Kazuyuki Tsurumi, FAO representative in the Philippines. "We have not committed any amount of money... [but] we are ready to support a wider surveillance and capacity-building for more tests," Tsurumi explained.

"We can't speculate. We don't know the source of this virus, how it's being transmitted. We're studying that," said Soe Nyunt-U, WHO Representative in the Philippines. "Our current issue is that the test kits are limited because we are depending on the [United States] CDC [Center for Disease Control and Prevention] to send those kits. If we are going to extend the surveillance both in the animal and human side, we need more test kits," he added.

Both the DA and DOH officials have decided to expand the scope of the testing for the Reston ebolavirus by inspecting and monitoring hog farms in the whole of Central Luzon, Calabarzon, Southern Luzon and Pangasinan province after the culling of the 6,500 pigs.

"As a precautionary measure, while there are many questions left unanswered, these ERV-contaminated pigs should be extinguished so we can move forward and study the virus," said BAI Director Davinio "Dave" Catbagan.

"In six months we might be finished testing Regions 3 and 4 depending on the assurance of the US Center for Disease Control and Prevention [in Atlanta Georgia, USA] to give test kits. In Region 3 alone, the government would need to test farms in 566 villages that would require around 36,000 kits, but the country only has 10,000 kits" Mr. Catbagan said. "The expanded tests will cover the provinces of Aurora, Bataan, Bulacan, Nueva Ecija, Pampanga, Tarlac and Zambales in Central Luzon, and Cavite, Laguna, Batangas, Rizal and Quezon in Calabarzon," Mr. Catbagan added.

Mr. Catbagan has assured infected hog farm owners in Pandi they would be properly indemnified after the country's first large-scale animal depopulation process. "We are finalizing the indemnification contract. But we will make sure the indemnification would not be open to abuse," he said. Fatteners and piglets cost an average of ₱3,000-4,000 per head, boars cost ₱25,000-30,000, and sows cost ₱14,000-15,000.

Intensively farmed pigs in batch pens

Juan Lubroth, senior officer of the Infectious Disease Group of FAO’s Animal Health Service, has arrived on Wednesday to discuss in detail with government officials how the agency can support in the wider surveillance. The DA and DOH officials and other government agencies met last Thursday to discuss and finalize the procedure in the burning of 6,500 pigs in Pandi, Bulacan.

"The Bureau of Animal Industry and the provincial government of Bulacan, experts carrying out the ₱500,000 five-day depopulation would observe three guidelines, namely: the main disposal, water safety, and environment protection. The depopulation process will involve stunning the pigs unconscious, burning them in a 6-foot deep pit, then burying them at the site. We want to make sure that our means would not violate the Animal Welfare Act. We are also ensuring that there would be no seepage," Governor Mendoza explained.

"Local authorities have decided to use electric prods and a ₱70,000 captive bolt pistol with a blunt rod to stun the 6,000 pigs in Pandi, prior to slaughter burning using rice hulls before burying them in a pit dug inside the hog farm," said Dr. Davinio Catbagan.

"About 40 health workers — clad in special hog mask suits and are tasked to facilitate the depopulation — would then dump the pigs into 10 30x30-foot pits that can accommodate 600 pigs each. The pits are located some 30 feet from the infected pig farm," said Mr Eric Tayag, head of the National Epidemiology Centre. "The cull could take up to seven days to complete," Mr Tayag added. A truckload of disinfectants was prepared amid rice husks to be used in the burning.

The Pandi culling will be the first large-scale depopulation because of a disease, according to Samuel B. Animas, chief of BAI's animal health division. "Only one to three pigs are slaughtered at a time in backyard farms during the foot and mouth disease infection [in the 1990s]," he added.

Meanwhile, at the 18th hog farmers convention, which was launched on Monday at Club Filipino, the president of the National Federation of Hog Farmers, Albert R. T. Lim, Jr., said hog farmers have feared the effects of Reston ebolavirus virus on industry, since hog exports were banned due to the outbreak. "We are also apprehensive that if we keep on talking about this thing, some people might just misconstrue or misunderstand what they are talking about and people might get scared," Lim said.

The government has spent about ₱10 million to maintain the two quarantined hog farms in Bulacan and Pangasinan. "Anyway, we always have our hog producers in Mindanao to supply Luzon if necessary. I am more concerned about our exports although the Ebola scare also somewhat affected local demand," Lim said.

Amid the nationwide ERV scare and probe, local authorities have seized more than 200 kilograms of rotten pork meat at a local market in Pasay City Wednesday. Barangay officials in Maricaban district have intercepted the banned ‘hot meat’ and arrested Roberto Clet and Rafael Fruelda, who were indicted under the "Consumer Act of the Philippines." The statute punishes the illegal sale of unsafe products like double-dead meat with penalty of ₱1,000 to ₱10,000 and not less than six-months but not more than five years of imprisonment.

Transmission electron micrograph of the Ebola virus.

Local police has also arrested four vendors and seized their 3,000 kilos of "botcha" (rotten pork meat or "double dead meat") at MC Market in Balintawak, Quezon City Wednesday evening, and allegedly delivered from Bulacan. The four suspects were charged for violation of the Consumer Act of the Philippines and Republic Act 9296 or the Meat Inspection Code.

In December, international experts initially probed outbreak among Philippine pigs, wherein about 6,000 pigs at Pandi and Talavera farms were tested for the Reston ebolavirus.

"There is no salmonella outbreak in Eastern Visayas, Region 8, said Dr. Archie Lluz, Chief of Regional Animal Disease and Diagnostic Laboratory of the Department of Agriculture in the region. But hog specimens from Leyte and Babatngon, where 270 swine deaths and cases of sick pigs were reported, were examined by lab tests. The results revealed cutaneous "Pasteurella hemolytica", a type of bacterial infection which causes swine deaths due to loss of appetite, dehydration, fever and diarrhea.

According to the DA, sick pigs had been culled from Babatngon, Tacloban City, Alangalang, Santa Fe, Palo, Pastrana, Dagami, Burauen, Tabontabon, Lapaz, Mayorga, and Abuyog in Leyte; Sogod in Southern Leyte; Catbalogan, Calbiga, Daram, and Santa Rita in Samar; and Lope de Vega in Northern Samar. Swine infections have spread to 18 towns and one city in Eastern Visayas.

The Reston ebolavirus is suspected to be a subtype of the Ebola virus or a new filovirus of Asian origin. It was first discovered in crab-eating macaques from the Philippines at a laboratory in Reston, Virginia. The same lab then recorded an outbreak of viral hemorrhagic fever among monkeys imported from the Philippines in 1990. The Reston ebolavirus strain was discovered among monkeys in the Philippines in 1996, and in Italy in 1992.

African strains of the virus caused deaths of about 50 percent to 90 percent of those infected with prior symptoms of lethal bleeding and organ failure, the WHO said. "Since the 1970s, scientists, veterinarians, microbiologists and physicians have been looking at thousands of species to see if they can find this elusive reservoir, and we have been pretty much empty-handed," Juan Lubroth, head of infectious diseases in the animal health unit of the Food and Agriculture Organization in Rome, explained.

"Unlike the three subtypes, Zaire, Sudan and Ivory Coast, which can cause hemorrhagic symptoms, Reston does not. There has been no evidence that Reston can cause significant illness in humans. When Reston was previously found in monkeys, few animal handlers were infected but only one had very mild symptoms," the DOH's official website announced.

In January 1997, the Philippines Department of Environment and Natural Resources ordered the immediate slaughter of some 600 monkeys in Ferlite, a breeding farm in Laguna, to prevent an outbreak of Reston ebolavirus.


  Learn more about the Reston ebolavirus and Pandi, Bulacan on Wikipedia.