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Why do livestock farmers keep experiencing avian flu outbreaks despite all the preventive measures? It's a question that researcher Francisca Velkers wrestles with on a daily basis. She is working with researchers from Wageningen Bioveterinary Research and Royal GD in an effort to find out how avian flu manages to penetrate the stables.

Velkers is conducting research at several affected poultry farms, using cameras and fluorescent agents to identify the cause. "We'll mimic a pile of bird droppings using fluorescent material. We can then apply that in various locations around the poultry houses. That allows us to monitor all sorts of things, like whether the virus is being introduced by pests. During one test, we saw mouse feet light up on shelving units near the feed storage area. That told us that pests were finding a way in. We're also testing whether livestock farmers are carrying the virus into their barns on the wheels of their wheelbarrows or their boots. We also inspect gutter systems. Droppings from wild birds on the roof could potentially enter a barn through splashes of rain near the air intake."

Installing cameras

Human error can also play a role in the spread of avian flu. "That's why we're applying fluorescent chemicals that only light up under UV light and installing cameras in the hygiene sluice," Velkers explains. "You can't just install cameras in secret, so we obviously tell the farmers. Everyone's very aware of the cameras at first, but we hope people will eventually go back to their normal behaviour. It's a great way of checking whether people are following the hygiene protocols Velkers is well aware that the protocols are quite a burden on livestock farmers. "They have to keep changing their clothes and even shower several times a day in some cases, which is time-consuming and demanding. You can't blame people for thinking: 'I'll just skip it this one time', but that can have serious consequences."

We need to look more closely at the role of insects like flies and beetles.

Invisible pathways
Poultry farmer Theo Bos has had plenty of experience with avian flu. His farm in Barneveld was culled due to infected chickens. "It's awful. I opened the stable doors for a second but I just couldn't bear the sight of all those dead chickens." The virus originated from wild birds perched on the roof of the barn. Bos has no idea how the virus made its way into the barn. That applies to lots of other livestock farmers too, which is why Velkers now wants to identify the invisible pathways. "Is the virus mainly entering the sheds through the hygiene sluice? Are mice introducing the virus as they crawl in through tiny holes? Are there any pathways we haven't even thought of yet? We hope this study will lead to the development of a new tool that farmers and veterinarians can use independently."

Lingering anxiety

"The lessons we learn from this research on avian flu," Velkers continues, "can also help us understand how other infectious diseases spread. That's still unclear in many cases. We're still fighting an invisible enemy at the moment." Poultry farmer Bos welcomes the research. "Anything that can help us stop this disease is more than welcome. Avian flu is intangible, you can't see the virus creeping in. One minute it's at the border near Maastricht and a week later it suddenly turns up 150 kilometres away." The chickens have since returned to Bos' stables, but there's still a sense of lingering anxiety. "I tend to get startled if I notice a chicken with a puffed up head or a chicken that's gasping for breath. That feeling doesn't go away until I see it scurrying around again later. We're doing everything we can to prevent bird flu. We only use the entrance through the hygiene sluice, we change our boots and overalls, and no one is allowed into the stables. It's a huge hassle, but we desperately want to avoid starting another outbreak ourselves."

We're doing everything we can to prevent bird flu. We don't want to be responsible for another outbreak.

Flies and beetles

As Velkers confirms, livestock farmers are vigilant when it comes to hygiene. "In the early days, some media reports suggested the outbreaks were actually being caused by the farmers themselves. But when I sat down with the same livestock farmer after a third cull and he told me he had followed all the previous guidelines, I also couldn't think what else they could have done to prevent avian flu. Livestock farmers are at their wit's end when that happens. That's why I'm trying to figure out what we're missing. The other day, a livestock farmer asked me whether it might have something to do with insects. That's when I realised we should be looking more closely at the role of insects like flies and beetles. We're going to assess that now in collaboration with pest experts. We need to find the missing link; that's the only way to fight avian flu more effectively."

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