Airborne transmission of pathogens emerging in the poultry industry

Poultry houses might have high levels of airborne pathogens, including Escherichia coli (E. coli) and avian influenza (AI), which may be transmitted through the air and pose risks of infection. The objective of the dissertation is to provide an insightful understanding the of airborne transmission of E. coli and AI which were attached to poultry dust particles.

Chapter I and VI summarized background, gap in knowledge, and discussed the limitations and implications of the study.

Chapter II compared the efficiency of Andersen six-stage impactor, all-glass impinger, and ACD-200 Bobcat, in collecting airborne E. coli carried by dust particles. The results showed that the Andersen six-stage impactor and the all-glass impinger outperformed the Bobcat sampler. Airborne E. coli were found to mainly aggregate on large particles (>7.0 µm).

The survivability of E. coli in poultry litter under different environmental conditions was described in Chapter III. The survivability of airborne E. coli was found to have a half-life time of 5.7 ± 1.2 min, while the survivability of settled E. coli and E. coli in poultry litter were much longer with half-life times of 9.6 ± 1.6 hrs and 15.9 ± 1.3 hrs, respectively.

The effect of ultraviolet (UV) light on the inactivation of airborne E. coli carried by poultry dust particles under laboratory conditions was explored in Chapter IV. The inactivation rates varied from over 99.87% and 99.95% at 5.62 s of contact time to 72.90% and 86.60% at 0.23 s of contact time, with 1,707 µW cm⁻² and 3,422 µW cm⁻² of UV irradiance, respectively.

Utilizing computational modeling to assess the risk of airborne and deposited AI carried by poultry-litter dust particles was investigated in Chapter V. Results showed that concentrations of airborne AI transmitted to other farms in a day were lower than the minimal infective dose for poultry. The study suggests that factors such as infected location and type of poultry house may influence the risk of airborne transmission of HPAI.

In conclusion, this dissertation explores sampling methods, survivability, mitigation technologies for airborne transmission of pathogens in poultry, and factors affecting infection probabilities in the poultry industry.