News broke a few weeks ago that a mold condition at Seattle Children’s Hospital left one child dead and sickened five others. Several of these children fell ill in 2018 and the others in 2019.

This begs a few very important questions: What kind of mold was it and how did this happen? In order to answer that, we need to dive deeper into the mold that was found. In this case, the mold species was Aspergillus. The hospital has not released the exact species that caused the illness or the factors that caused it to grow.

According to the CDC, there are approximately 180 species of Aspergillus and less than 40 of them are known to cause infections in humans. In fact, aspergillus sojae is used for the preparation of fermented foods. Aspergillus oryzae is used to help ferment soybeans to make soy sauce and to prepare miso. EMSL Analytical has a very informative fact sheet on aspergillus which you can review here.

So, how could the mold have grown in the hospital? Aspergillus is spread primarily by wind and its spores make their way into buildings through open windows, doors, and other means of ingress from the outdoors. It grows on a wide range of substrates indoors. It is very commonly found in water damaged environments. A plausible theory is that there was a water condition on a viable substrate at some point that either was not even known about or was not re-mediated perfectly which caused the mold to grow. Building materials such as wood have a tendency to easily absorb water when exposed to it but does not dry out as easily.