Coarse particles and insects can enter the air intakes of poultry farms with the air. These may 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 flu virus in our research, we do advise poultry farmers to take additional measures to minimize the potential risks of this route of introduction via the air intake,’ says WBVR researcher Armin Elbers. More research is needed to map out the effectiveness of various measures.
At two recently infected farms, one broiler farm and one laying hen farm, after culling and several rounds of cleaning and disinfection, WBVR placed a ventilation hood over the inlet valve at eighteen air inlets per house. A fine mesh net is also attached to it.
The ventilation was operated as if poultry were present. The fine mesh net collected wild bird feathers, plant material, cobwebs, plastic, wool and manure material. In addition, a video camera monitoring system has been installed by WBVR. This recorded the visit of wild birds to the area around the stable.
Fine mesh nets
The contents of the fine mesh nets were harvested every five days from January to March 2022 on both poultry farms for a total of 25 days. The fine mesh nets were also swabbed with a duster. Incoming material, duster and captured insects were tested for influenza virus, campylobacter and salmonella. The insects were also tested for Schmallenberg, West Nile and Usutu virus.
The researchers found small amounts of material in the nets. This varied from small pieces of plant and/or crop material, pieces of plastic and paper, to wool and spider web. No feathers or droppings from wild birds were observed. Cobwebs and plant matter were most commonly observed, averaging about one to two cobwebs or plant matter per air inlet per five day collection period.
However, the variation in the amount of material entering through the various air inlets was large. During an occasional storm with strong wind, large amounts of material can enter the house through the air inlets on the windward side.
No virus found
All material samples tested were negative in the PCR test for influenza virus and salmonella. The insects tested negative for Schmallenberg, West Nile and Usutu virus. Evidence has been found for the introduction of campylobacter via the air intake. The area at a short distance, up to 10 metres, from poultry houses was regularly visited by wild birds such as the blackbird, carrion crow, black-backed gull, oystercatcher and mallard.
The research indicates that coarse particles and insects, which may be infected with bird flu or other pathogens, can enter poultry air intakes with the air. ‘It is therefore wise to limit this potential route of introduction’, says WBVR researcher Armin Elbers.
Restrict introduction route
However, according to Elbers, more research is needed to understand how this can be done properly: ‘The use of windbreak mesh may contribute to limiting this route of introduction.’ He also knows a company that installed windbreak mesh a few years ago after an infection with bird flu.
‘That company has now become infected again, whereby it is likely that this happened via air supplied via the air inlet. Windbreak mesh is therefore not a cure-all,’ he says. Elbers believes that the use of an automated laser is a good alternative. ‘This makes the area around the poultry house unattractive to visiting wild birds.’