Prevalence of and environmental factors associated with aerosolised Aspergillus spores at a zoological park

Aspergillus is a significant pathogen in zoological species, although information on environmental variables influencing fungal prevalence in zoological settings are lacking. The objective of the study was to estimate the prevalence of and to identify environmental factors associated with aerosolised Aspergillus spores at a zoological park to advance the understanding of fungal exposure as a first step towards improved mitigation strategies for susceptible animals. Twenty-one locations were sampled for presence of Aspergillus species using the SAS Super 180 Microbial Air Sampler, while twenty-two environmental factors were evaluated every two weeks at SeaWorld of California during two 12-month periods. In each period, the frequency of investigated environmental factors was compared between samples classified as positive or negative for Aspergillus species using logistic regression. Prevalence of Aspergillus was higher (P<0.05) during the second 12-month period (110/525 or 21 per cent), compared with the first period (62/483 or 13 per cent). In both periods, positive Aspergillus samples were associated with indoor sites without high-efficiency particulate air (HEPA) filtration systems and other infection control measures (adjusted OR=4.33 and 5.19, P<0.01) or outdoor sites (adjusted OR=2.50 and3.79, P≤0.05), compared to indoor sites with HEPA filtration systems and other infection control measures, after controlling for season. Burden of airborne Aspergillus can be higher in indoor sites without HEPA filtration systems than in outdoor sites. The use of HEPA filtration systems and other infection control measures can mitigate the burden of Aspergillus. Risk-based surveillance systems that target indoor areas without HEPA filtration systems can be an efficient approach for early detection of high burden of Aspergillus at zoological parks.