Coarse particles and insects can enter the vents of poultry houses with the air. These can be infected with bird flu or other pathogens. This has emerged from research by Wageningen Bioveterinary Research (WBVR) and Utrecht University.
“Although we did not find an avian influenza virus in our research, we advise poultry farmers to take additional measures to minimize the potential risks of this route of introduction via air ingress,” says Armin Elbers, WBVR researcher. More research is needed to map out the effectiveness of the various measures.
On two recently infected farms, a broiler farm and a laying hen farm, after culling and several rounds of cleaning and disinfection, WBVR placed a vent hood over the eighteen vent inlet valve to shed. A fine mesh net is also attached to it.
The ventilation was managed as if poultry were present. The fine-mesh net collected wild bird feathers, plant material, cobwebs, plastics, wool, and manure. Additionally, WBVR has installed a camera monitoring system. This recorded wild birds visiting the area around the barn.
Fine mesh nets
The contents of the fine mesh nets were collected every five days from January to March 2022 at both poultry farms for a total of 25 days. Even the fine mesh nets were cleaned with a duster. Incoming material, feather duster and captured insects were tested for influenza virus, campylobacter and salmonella. The insects were also tested for Schmallenberg, West Nile and Usutu viruses.
The researchers found small amounts of material in the networks. This ranged from small pieces of plant and/or crop material, bits of plastic and paper, to wool and cobweb. No wild bird feathers or droppings were observed. Cobwebs and plant matter were most commonly observed, averaging about one to two cobwebs or plant matter per air input over a five-day collection period.
However, the variation in the amount of material entering through the various vents was considerable. During an occasional storm with high winds, large quantities of material can enter the house through vents on the windward side.
No viruses detected
All material samples tested were PCR negative for influenza virus and Salmonella. The bugs tested negative for Schmallenberg, West Nile and Usutu viruses. Evidence has been found of the introduction of campylobacter through the snorkel. The area within 10 meters of the poultry houses was regularly frequented by wild birds such as blackbirds, carrion crow, black-backed gull, oystercatcher and mallard.
Research indicates that coarse particles and insects, which may be infected with avian influenza or other pathogens, can enter the air vents of poultry. “It is therefore wise to limit this potential route of introduction,” says WBVR researcher Armin Elbers.
Limit the input path
According to Elbers, however, more research is needed to understand how to do this correctly: “The use of windbreak nets can help limit this route of introduction.” He also knows a company that installed a windbreak some years ago after a bird flu infection.
‘That company has now been re-infected, so it is likely that this was via the air supplied through the vent. The windbreak net is therefore not a panacea,’ he says. Elbers believes using an automated laser is a good alternative. “This makes the area around the chicken coop unappealing to visiting wild birds.”
