THE poultry farms in Candaba, Pampanga—not in neighboring San Luis—may be the ground zero where the country’s bird-flu epidemic was first found, the BusinessMirror learned.
This was part of the hypotheses of the Food and Agriculture Organization (FAO) study on the country’s bird-flu outbreak in August 2017, according to the Bureau of Animal Industry (BAI).
The FAO was tapped by the government last year to trace the causality of the country’s first confirmed avian-influenza (AI) outbreak.
BAI-Animal Health and Welfare Division Chief Dr. Arlene Vytiaco told the BusinessMirror that the FAO study had two hypotheses on how the AI was introduced to the country: 1) through migratory birds and 2) through smuggled bird flu-infected poultry commodities.
Vytiaco said the FAO study hypothesized that the country’s very first AI case may not be in San Luis but in Candaba, due to migratory birds.
The possibly AI-affected migratory birds could have overstayed in the area and mingled with the free-grazing duck population in Candaba. Shorebirds or migratory birds and ducks are known to be carriers of bird flu viruses.
“It is possible that San Luis, which we are referring to as the ground zero, may not be the area where the [AI virus] started,” she said in an interview.
“The FAO report is saying that Candaba was hit first by AI even before San Luis. The report noted that as early as April, or even March, there has been unusual mortality [in poultry population] in Candaba,” she added. Vytiaco explained that the government was not able to establish the index case, or the very first farm affected by AI, due to non-reporting by farmers. This, she said, delayed the discovery of the problem and San Luis was later identified as the ground zero.
On the possibility—as noted in the FAO report—that Candaba poultry farms were affected by AI through migratory birds, Vytiaco said, “Migration period of birds starts as early as September and [they] stay in the country until February, with some overstaying until March.”
Thus, it “is possible that [the deaths of poultry flocks in Central Luzon] did not start in July but in April. Because if some migratory birds stayed until March and considering the incubation period of about 21 days, it is highly possible that population in Candaba was affected in April,” Vytiaco added.
Smuggling
Vytiaco said the FAO report indicated that smuggling of bird flu-affected poultry and poultry commodities could also be behind the AI.
However, the report, according to her, wasn’t able to trace the timeline on when the smuggled poultry products could have entered the country, as no index case was established. “[However], with vague timeline for index case, the identification of imported poultry and poultry [timeline is difficult].”
With these, the FAO study noted that it was “inconclusive” to determine the concrete reason behind the introduction of AI in Central Luzon, Vytiaco said.
Vytiaco noted that the study was conducted for only about three months, September to December, last year. It usually takes two years to concretely determine the AI virus pathway, according to her.
“These are all hypotheses of the FAO study, which…cannot be proven although they are very highly possible causes,” Vytiaco said.
Mutation
Furthermore, Vytiaco explained that the presence of a highly pathogenic AI H5N6 could only be a result of mutation between an already present low pathogenic AI and H5N1.
“There were two factors to establish the presence of H5N6 in an AI-free area. One is the presence of low pathogenic strain and the second the presence of H5N1,” she said, quoting the FAO study.
“When these two mix and mutate, it would result in H5N6. And the FAO noted that both low pathogenic [AI] and H5N1 could be introduced by migratory birds,” she added.
Spread
Vytiaco said the FAO listed three potential “high risk actors for the introduction and maintenance of infection within the poultry population” in Central Luzon.
First, the virus could have spread from Candaba to San Luis due to dumping by poultry farmers of carcasses in the Pampanga river.
“And based on the outbreak, the current of the river [then] was heading to San Luis,” she said. Candaba is 20 kms north of San Luis.
Under the Avian Influenza Protection Program: Manual of Procedures 2016, eight barangays in Candaba were tagged as poultry-critical areas, meaning, vulnerable to the introduction of AI. These are Bahay Pare, Paligui, Pangclara, Pulong Gubat, Tenejero, Vizal San Pablo, Dawe and Lourdes.
These villages have waterfowls, shorebirds and duck grazing areas with a duck population of more than 5,000 heads.
Citing the FAO study, Vytiaco said the free grazing ducks in San Luis could have had contact with the contaminated river and roamed around the area, causing the spread among layers and quail farms.
Another risk factor was technical assistance, referring to private veterinarians and sales representatives, according to Vytiaco. Some veterinarians visiting various poultry farms may have misdiagnosed the sick population as affected with newcastle disease (ND).
“Because it was a misdiagnosis, and these veterinarians handle about three to five farms, they transfer from one farm to another. They believed that it was ND instead of AI, they eventually came carriers,” she said.
Poultry traders were the last factor cited by the FAO study, which, however, tagged them as a protective factor, as well.
“They are protective to farm owners because they know what is happening in the industry. So they could urge the poultry owners to sell their chickens early because other poultry population are already dying,” she explained.
But because the traders did not know the flocks they bought could have been affected by AI, they effectively became carriers of the virus, as well, Vytiaco added.
Furthermore, Vytiaco said based on the FAO study, the infection of three towns in Nueva Ecija with bird flu were “spillover” cases from San Luis.
Vytiaco said culled chickens bought by traders in San Luis were brought to San Isidro, Nueva Ecija, which later tested positive for AI as well.
“When the FAO mapped the location of the infected farms in San Isidro, they found that they were just right across the live bird market in the area,” she said.