When you think about the over 5M fungal species that exist on the planet and juxtapose this against the approximate 2000 mushrooms species we might eat as food - there really are a lot of chance and probable possibilities for us to come into contact with these microorganisms in our everyday lives.
This new paper that came out from the Lawrence Berkeley National Laboratory is quite an eye-opener because it looked at how fungal communities inside 1135 homes in the United States is connected with something called the Infection Fatality Ratio (IFR) which describes the number of deaths caused by COVID-19 per 1000 coronavirus infections.
Their research showed that an increased fungal diversity especially for specific Species of indoor fungi versus outdoor fungi (Beta diversity) was associated with a reduced infection fatality ratio.
In their paper, they looked at whether there was a correlation between certain Species of fungi and adverse outcomes from COVID? And amazingly they found that “yes” there is!
They found that something called the beta diversity assessed from a comparison between fungal spore types collected outdoors and then inside the home living environment was of fundamental importance.
The key result is that: high diversity of outdoor fungi when also present indoors is associated with a suppression effect for COVID-19 mortality.
This means that collecting spore trap measurements from the outdoors and indoors is very important for predicting adverse events like mortality from COVID-19 and emphasizes the importance of the environment on human illness. Now it’s not just the raw numbers of fungi, but the overlap of which types are present outdoors and also found indoors which defines different aspects of Species richness and diversity.
The research showed that at least four of the following seven fungal genera have a key role in suppressing coronavirus infections. These were: Alternaria, Aspergillus, Epicoccum, Eurotium, Toxicocladosporium and Wallemia as well as a novel Mycosphaerellaceae fungus.
You could argue that simply airing out your property will naturally bring fresh outdoor air containing mould spores indoors. So, wouldn’t that automatically select for the correct beta diversity ratio that’s better for your health?
On the surface, you'd be right to conclude this. However, I've personally done 1000s of indoor air quality inspections over the years and many homes have hidden mould problems that contribute to poor indoor air quality. This is often caused by water damage and dampness and in most of these cases, there is a skewed distribution of fungi indoors that’s very different to the outdoors.
This publication is extremely important because it shows a correlation effect between bioaerosol counts especially mould spores and respiratory disease outcomes. The key takeaway here is that COVID-19 mortality is suppressed inside homes where the outdoor fungi occur indoors at very similar levels.
When the skewness or difference between the outdoor: indoor diversity changes, or when the indoor fungi are significantly different to the outdoors, then COVID-19 mortality increases.
These researchers found that fungal beta diversity was a much stronger correlate for adverse COVID-19 outcome as age. For example, older persons have worse COVID-19 outcomes, and this paper says that fungal beta diversity in the wrong direction is also bad for your health. The authors stress the method is unlikely to be restricted only to coronavirus but could extend to surveillance of other allergic and viral diseases. This research, therefore, underscores the importance of fungal biosurveillance in the built environment to improve public health outcomes.