Agriculture News Analysis

Threat lurks in the wings

bird flu outbreak in the town of San Luise, Pampanga, Philippines

As Philippine troops battle Muslim extremists in the south and lawmen continue their war against drug gangs around the country, on the northern island of Luzon another potential enemy has emerged – bird flu. Some 200,000 fowl – chickens, ducks and quail – are to be slaughtered following the order for an immediate cull by the Department of Agriculture (DA). That’s already underway; the problem is the infection of birds in this area goes back to April – it seems farmers failed to report the deaths of thousands of birds on their farms. Getting a grip on all this will now be at the very top of the DA’s busy to-do list.

At the centre of the scare is the farming town of San Luis on the eastern side of Pampanga province bordering Bulacan. Its main claim to fame up until now has been that it’s the birthplace of Luis Taruc, the agrarian reformist and leader of the Hukbalahap, a 10,000-plus-strong communist guerilla army that fought the occupying Japanese during World War II. But the invasion of a potentially lethal virus in this place presents a serious threat in its own right.

Central Luzon – Region 3, in which St Luis falls – is the heartland of Philippine chicken production. It has a stock of 19.2 million chickens; that’s nearly a third of the country’s entire inventory. Of the Philippines 1.66 million tons of chicken production in 2015, the lion’s share – 1.13 million tons – came from Luzon farms.

What’s in the immediate area of San Luis is Candaba Swamp; a wetland area which has been cited as a potential breeding ground for the avian-influenza virus in the past. In 2005, the Department of Health along with the Department of Environment and Natural Resources placed Candaba under close monitoring. The fear then – as now – is that migratory birds, using the swamp as a way station on their flight path, could be virus carriers.

However, this is the very start of the migratory season which usually begins in earnest in September. That said, these wetlands – comprising swamps, marshes and freshwater ponds, and covering an area of around 32,000 hectares – will be a main focal point of DA investigations.

In 2011, the department swung out a nationwide avian-flu testing programme, taking 1,950 blood samples from ducks – known carriers of the disease – across the three island regions of Mindanao, the Visayas and Luzon. Of those tests, 280 were taken from an area around Candaba Swamp.

That part of the programme was conducted by a laboratory in San Fernando, Pampanga’s provincial capital, which was set up in 2007 at a cost of US$340,000 and funded by the New Zealand Government. The location was chosen largely because of the perceived threat of the virus breeding at Candaba Swamp.

The aid was given to improve the Philippines’ preparedness in the event of an avian-flu outbreak. This included better diagnostic surveillance of avian influenza by means of accurate poultry population censuses nationwide, targeted surveillance (such as the 2011 study), laboratory-testing facilities and the maintenance of an information management system and the conduct of research-based public awareness activities.

There are a number of such lab facilities in the Philippines, including at the Bureau of Animal Industry in Quezon City, Manila; in Cebu and Cagayan de Oro, and Zamboanga in Mindanao which established its Regional Avian Influenza Laboratory one year after the San Fernando lab opened.

All these have helped to keep the archipelago on top of dealing with a potential outbreak. Now they’ll all be thrown into high gear to test for the virus in other parts of the country. The trick is to track it down quickly and reduce the incidence of further contamination – something which the delay in reporting by the San Luis farmers will have seriously hampered.

The DA is taking no chances with this event and has also sent blood samples of affected poultry to both the World Organization of Animal Health and the Australian Animal Health Laboratory – a large facility in Geelong, Victoria – for further testing.

For one thing, we’ve yet to learn exactly which subtype of bird flu has been found at the six Luzon farms where the outbreaks occurred and which, along with the swamp, are now at the centre of the DA’s investigations. All we know is that it’s Type A, subtype H5. But that’s still leaves a wide field with six possible H5 strains – H5N1, H5N3, H5N4, H5N7, H5N8 and H5N9 – from which to identify the subtype.

Of these, the one that would be of real concern to the DA and the Department of Health (DOH) is the highly pathogenic H5N1 – one of just two H5 strains known to affect humans. The other is the extremely rare H5N7 which so far has never appeared in Asia. (Three H7 strains and one H9 strain can also jump from bird to man). But while human-to-human transmission rates for H5N1 are low, mortality rates are extremely high – possibly as high as 60%.

The H5N1 virus first appeared in China in 1996 and since then it’s caused hundreds of deaths and infections as it’s travelled across the entire Asia continent – some 40% of all cases have occurred there – most of Europe and parts of Africa. Southeast Asia has been particularly prone to H5N1 with outbreaks and resulting deaths recorded in Laos, Cambodia, Vietnam, Malaysia, Thailand and Indonesia. Incredibly, given the virus’s presence in the region, the San Luis outbreak is the first recorded incidence of it in the Philippines.

The big worry, though, is human-to-human transmissions, making it a potential lethal conduit for a pandemic. The fear, according to the World Health Organisation (WHO), is that this strain could mutate to a form that’s highly transmittable between humans. The WHO – along with the World Organization of Animal Health – has been informed of the situation by the DA and will be watching developments in Luzon very closely.

The first recorded human-to-human transmission was in Hong Kong in 1997 – an outbreak in which 18 people were infected. Six died from the disease. It had been brought to the city by a human carrier who’d recently arrived there from China. This was the first time in history that a virus had been known to leap from birds to humans. And the fact that it could be contracted human-to-human raised its profile even further. It took the medical world completely unawares; as a leading virologist explained at the time, “This is like the clock striking 13”.

But since then, the clock’s struck 13 with nearly every outbreak. And this must be a main concern for the DOH right now. And particularly since this the San Luis outbreak started some four months ago. Just as immediate quarantining of affected farms is essential in containing the virus, fast screening of everyone who’s been in contact with the virus is also vital. In both areas – health and agriculture – the number one imperative is to stop the virus’s spread.

This is now in train and a seven-kilometre sanitation cordon has also been set up around the area, halting the transporting of all poultry products. Products that have already left the farms – outlets for these are all in the locality according to the DA – will also be tracked down and destroyed. What remains to be seen, though, is whether the horse had bolted before the stable door was shut.

The DA will want to know if birds from those farms had gone to other farms further afield – and if farm workers from those farms have visited other farms with the potential of trampling the virus further. What we know so far is that this outbreak started on a single farm and was spread to five others. The question is, are chickens and ducks dying of avian flu on other farms in the region?

Meanwhile, the DOH has been monitoring farm workers who’ve had exposure to infected birds on the small holdings so far identified with the disease. It’ll also have alerted hospitals and clinics in the area to be on the lookout for patients with avian-flu symptoms.

Worrying times; but hopefully, what killed the chickens and the ducks in San Luis will prove to be one of the other forms of the H5 virus. If it is, then this should provide a salutary lesson for farmers on the need to report suspected cases of avian-flu deaths among their poultry stocks to the DA quickly. Just as the early bird catches the worm, the vigilant farmer will catch the diseased bird early.

Some 37,000 ducks, chickens and quail perished from the virus on the farms around San Luis before the alert was raised. That’s big bird deaths and they should have been spotted pretty much immediately; once a pattern had been established. The outbreak is thought to have peaked some time in July, but had farmers not dismissed their dying poultry as some “ordinary” poultry disease as those farms did, it would never have reached these levels of contamination.

There’s also likely to be a big bill for all this – destroying and disposing of 200,000 birds, testing contaminated foul, thoroughly disinfecting the farms, disposing of poultry-meat products; all the manpower involved in that. Plus the cost of restocking those farms; for sure, it won’t be chicken feed.

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