Your dishwasher, vacuum cleaner and compost are trying to kill you! Or are they?

In the last 24 hours I saw articles with the following three headlines:

My dishwasher is trying to kill me: Extreme conditions suit pathogenic fungus.

Compost Harbors Legionnaire’s Disease Bacteria

Bacteria, Mold Found In Vacuum Dust

You’re not safe anywhere!  And people wonder why microbes get such a bad rap.   Yes, of course some microbes cause disease.  But most of them don’t and I think it doesn’t help anyone other than the companies who sell cleaning solutions and put Triclosan in your toothpaste to spread unjustified fear.

So here’s my quick take on each of these three stories.

Dishwasher:

In this study, researchers found a number of fungal species living in dishwashers, including a couple species associated with human disease.  Cool.   And interesting.  Does this justify the headline “My dishwasher is trying to kill me”?  I don’t think so.  In fact the actual paper concludes with:

In conclusion we have shown that dishwashers are among household machineries that provide a specific habitat for polyextremotolerant, potentially human pathogenic fungi.

So worthy of further study but without knowing the actual risk of either these fungi, or their presence in dishwashers it’s not worth calling out the National Guard (who are probably furloughed right now anyway).

Compost

This one is my favorite of the three.   Researchers found Legionella in a bunch of compost samples.  So what?  I could go out to pretty much any body of water and find Legionella living in it since the natural host is freshwater amoebae.  This includes a very large percentage of built environment water systems as well.  Legionella is an opportunistic pathogen, meaning that it’s out there in the environment and accidentally infects people.  The most common species that they found in this study was Legionella longbeachae which is often found in… soil!

Vacuum Cleaner

This study basically concluded that vacuum cleaners stir up house dust.  And that house dust contains “human-associated bacteria”.  And some of these bacteria even contain antibiotic resistance genes.  Well… yeah.  Unless you’re a bird, your house is full of human-associated bacteria.  It’s already well-understood that disturbance of dust is associated with the aerosolization of bacterial particles.  In fact just walking across carpet is known to put a bunch of particles into the air.   Does this mean there is a health risk associated with vacuuming?   Who knows but there are a lot of other things I would worry about first.

I think the biggest issue is that a lot of these studies (or at least their press releases) confound “we found it” with “there’s a health risk”.   For example, anthrax is really common in the environment… I’d bet most of you could find it in your house if you looked hard enough.   When was the last time you heard about someone getting anthrax from hanging out at home?   Just because it’s there doesn’t mean it’s a problem.