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Volume 32, Number 3—March 2026

Research

Environmental and Phylogenetic Investigations of Aspergillus flavus Outbreak Linked to Contaminated Building Materials, Denmark, 2025

Alexander Gewecke, Raphael Niklaus Sieber, Søren Hallstrøm, Marc Stegger, Barbara Kolarik, Jenny D. Knudsen, Birgitte Andersen, Astrid Hall, Nadja Hawwa Vissing, and Maiken Cavling ArendrupComments to Author 
Author affiliation: Statens Serum Institut, Copenhagen, Denmark (A. Gewecke, R.N. Sieber, S. Hallstrøm, M. Stegger, M.C. Arendrup); Harry Butler Institute, Murdoch University, Perth, Western Australia, Australia (M. Stegger); dansk MiljøAnalyse, Vedbæk, Denmark (B. Kolarik); Copenhagen University Hospital, Rigshospitalet, Copenhagen (J.D. Knudsen, A. Hall, N.H. Vissing, M.C. Arendrup); Aalborg University, Copenhagen (B. Andersen); University of Copenhagen, Copenhagen (M.C. Arendrup)

Main Article

Table 1

Comparison of fungal yield for paired sampling of air and surfaces in study of environmental and phylogenetic investigations of Aspergillus flavus outbreak linked to contaminated building materials, Denmark, 2025*

Identification Air, n = 82
 Surface, n = 82
 Total CFUs
25°C
 37°C
 25°C
 37°C
CFU (CFU/m3) Median (range) CFU (CFU/m3) Median (range) CFU (CFU/25 cm2) Median (range) CFU (CFU/25 cm2) Median (range)
Aspergillus 186 (4.5) 0.0 (0–28) 26 (0.6) 0.0 (0–13) 321 (7.8) 5.0 (0–55) 491 (12.0) 6.0 (0–70) 1,024
A. calidoustus 179 (4.4) 0.0 (0–28) 3 (0.1) 0.0 (0–1) 13 (0.3) 0.0 (0–4) 39 (1.0) 0.0 (0–27) 234
A. flavus 3 (0.1) 0.0 (0–1) 5 (0.1) 0.0 (0–4) 236 (5.8) 2.0 (0–55) 349 (8.5)† 2.0 (0–63) 593
A. fumigatus 2 (0.0) 0.0 (0–1) 18 (0.4) 0.0 (0–13) 1 (0.0) 41 (1.0) 0.0 (0–14) 62
A. niger 2 (0.0) 0.0 (0–1) 0 (0.0) 42 (1.0) 0.0 (0–23) 62 (1.5) 0.0 (0–34) 106
Aspergillus NI 0 (0.0) 0 (0.0) 29 (0.7) 0.0 (0–25) 0 (0.0) 29
Other fungi
Alternaria 4 (0.1) 0.0 (0–3) 0 (0.0) 38 (0.9) 0.0 (0–6) 1 (0.0) 43
Aureobasidium 6 (0.1) 0.0 (0–2) 0 (0.0) 6 (0.1) 0.0 (0–6) 2 (0.0) 0.0 (0–1) 14
Cladosporium 154 (3.8) 2.0 (0–23) 0 (0.0) 131 (3.2) 1.0 (0–15) 0 (0.0) 285
Geotrichum 0 (0.0) 1 (0.0) 0 (0.0) 0 (0.0) 1
Mucorales 2 (0.0) 0.0 (0–1) 2 (0.0) 0.0 (0–1) 8 (0.2) 0.0 (0–1) 2 (0.0) 0.0 (0–1) 14
Penicillium
 118 (2.9)
 2.0 (0–20)
26 (0.6)
 0.0 (0–10)
135 (3.3)
 0.0 (0–33)
24 (0.6)
 0.0 (0–19)
 303
Molds NI 20 (0.5) 0.0 (0–16) 0 (0.0) 1 (0.0) 3 (0.1) 0.0 (0–2) 24
Growth NI 2 (0.0) 0.0 (0–1) 0 (0.0) 0 (0.0) 2 (0.0) 0.0 (0–2) 4
No growth
 3
26
3
13
45
Fungi in total 492 (12.0) 9.0 (0–44) 55 (1.3) 0.0 (0–13) 640 (15.6) 13.0 (0–59) 525 (12.8) 6.0 (0–71) 1,712

*Samples were taken from 41 locations on the outbreak floor in March 2024 and cultured at 25°C or 37°C . Bolding highlights A. flavus findings. NI, not identified. †p<0.001 for culturing surface samples at 37°C versus 25°C (A. flavus).

Main Article

Page created: January 21, 2026
Page updated: March 20, 2026
Page reviewed: March 20, 2026
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