Revealing Stachybotrys-like fungal growth in buildings - Possible exposure highlighted through three case studies

Genus Stachybotrys (Stachybotryaceae, Hypocreales) requires high humidity to grow and represents one of the most notorious fungi associated with suspected illness in moist buildings. If Stachybotrys conidia are found in settled indoor dusts, their presence may indicate water intrusion and mold infestation revealed after dismantling the building structures. This study describes detection of Stachybotrys growth hidden inside the structures of three buildings in Finland. First, a novel microscopic screening method concentrating Stachybotrys conidia from settled dust was developed. The method is based on enrichment of conidia floating in the solution of saturated NaCl, separating them from sinking dust particles. Captured conidia were identified based on morphology and cultivated isolates were identified to species or genus level. The second part of the study describes the records of two persons sickened with asthma after exposure to long lasting growth of Stachybotrys in two of the buildings. After 38 years of the diagnosis the one person's asthma was declared cured in a medical report. The asthma of the other person developed into chronic illness, diagnosed by The Insurance Court as occupational asthma caused by a moisture-damaged workplace. Diversity and the metabolic activity of the microbes exposing the two persons in rural versus urban environments after their asthma diagnosis is offered as a preliminary and hypothetical explanation of the different outcome of the illnesses.