Monitoring Wind-Borne Particle Matter Entering Poultry Farms via the Air-Inlet: Highly Pathogenic Avian Influenza Virus and Other Pathogens Risk

Abstract

Wind-supported transport of particle matter (PM) contaminated with excreta from highly pathogenic avian influenza virus (HPAIv)-infected wild birds may be a HPAIv-introduction pathway, which may explain infections in indoor-housed poultry. The primary objective of our study was therefore to measure the nature and quantity of PM entering poultry houses via air-inlets. The air-inlets of two recently HPAIv-infected poultry farms (a broiler farm and a layer farm) were equipped with mosquito-net collection bags. PM was harvested every 5 days for 25 days. Video-camera monitoring registered wild bird visits. PM was tested for avian influenza viruses (AIV), Campylobacter and Salmonella with PCR. Insects, predominantly mosquitoes, were tested for AIV, West Nile, Usutu and Schmallenberg virus. A considerable number of mosquitoes and small PM amounts entered the air-inlets, mostly cobweb and plant material, but no wild bird feathers. Substantial variation in PM entering between air-inlets existed. In stormy periods, significantly larger PM amounts may enter wind-directed air-inlets. PM samples were AIV and Salmonella negative and insect samples were negative for all viruses and bacteria, but several broiler and layer farm PM samples tested Campylobacter positive. Regular wild (water) bird visits were observed near to the poultry houses. Air-borne PM and insects-potentially contaminated with HPAIv or other pathogens-can enter poultry air-inlets. Implementation of measures limiting this potential introduction route are recommended.

Keywords: Campylobacter; Salmonella; avian influenza virus; bird feathers; cobweb; faecal material; highly pathogenic avian influenza; insects; particle matter; plant; wild aquatic avian species.

Figure 1

Air-inlets in the poultry house and air-inlets equipped with SKOV ventilation cap and collection netting.

Figure 2

Examples of particle matter collected and measured with a ruler. In the left picture: seeds, plastic and leaf material. In the right picture: several pieces of cobweb with accumulated dust.

Figure 3

Video-camera installed to cover part of the area and roof of the poultry house under study.

Figure 4

Distribution of the number of particle matter per air-inlet per 5-day collection period (total: 5 collection periods) in the broiler and layer house (A). Distribution of particle matter size from the air-inlets of the broiler and layer house (B). (fat dark line in the box: median; lower end of the box: 25% quantile; higher end of the box: 75% quantile; highest bullet or high end of the vertical line coming out of the box: highest value; lowest bullet or low end of the vertical line coming out of the box: lowest value). Note: The Y-axis of Figure 4A is cut off to prevent a disproportional layout with outlier cobweb measurement values up to 60 per air-inlet entries per 5-day collection period for the layer house.

Figure 5

Distribution of the number of arthropods per air-inlet per 5-day collection period in the broiler and layer house; total 5 times 5-day collections per house (fat dark line in the box: median; lower end of the box: 25% quantile; higher end of the box: 75% quantile; highest bullet or high end of the vertical line coming out of the box: highest value; lowest bullet or low end of the vertical line coming out of the box: lowest value). Note: The Y-axis of Figure 5 is cut off to prevent a disproportional layout with outlier mosquito numbers up to 65 per air-inlet entries per 5-day collection period for the broiler house.

Figure 6

Distribution of the total number of wild birds visiting (by order and observation day) the area close to the broiler house (A) and layer house (B) during the study period.