Should you take your shoes off after coming inside? Controversial subject! Growing up, my family wore shoes in the house. I didn't but I wasn't into wearing shoes or socks. My Mom always told me that you should make your guests comfortable so when people come over, spot the pile of shoes in the entryway and ask me what they should do I just say, "whatever you prefer." One of my friends has orthotic inserts and his feet start to hurt if he's not wearing his shoes so of course he can keep them on! I lived in a pretty gross 'hood for a long time (notorious for it’s poop problem) and the thought of tracking any of that stuff inside made me super wary to leave my shoes on. You’re just as likely to transfer something from your shoe to your hand and then to the fridge door or to your backpack (and other fomites) after taking them off as you are to grind some urban bread into the carpet (which will absorb it).
But just for fun, here’s a brief list of things that can live in poop and infect you via the “fecal-oral route:”
I’m going to guess that it’s pretty unlikely that any of my friends, adventurous as they are, are going to be transmitting tapeworms through a shared bowl of popcorn while we binge watch House of Cards. Also no one in our state has polio (I’m not counting E-68) so I think we’re OK there as well. The bad news is the things that thrive in poop are pretty hardy! Giardia is definitely sturdy and can live for a few months in its cyst form. Giardia causes diarrhea and severe intestinal distress and sometimes death. It’s pretty common in dog poop. Hep A can also live for several months outside the body. E. coli and other bacteria from the list can’t live very long unless they’re in a humid environment (looking at you, poop) and then its lifespan is variable. If you’re tracking sidewalk sauce into the house, it’s not likely to survive long, especially if the carpet or linoleum is dry.
Curious, I swabbed my shoes, grew it up, checked it out under the scope live and stained to see what came up and it was mostly the classics. There’s some yeasts, some E. coli, some Bacillus and some Pseudomonas aeruginosa. All easily washed away with some soap and water.
While I'm a shoes-off type, I do have a dog, and he's terrible at wiping his paws on the door mat before coming in. He's also allowed on the sofa (extra gross). However, I was surprised to find after swabbing his paws and growing up the sample on some agar plates that his feet are much cleaner than I expected. His samples grew up some Bacillus looking critters (guessing subtilis) which is part of a normal gut microbiome and doesn’t cause infection. I was expecting E. coli for sure, but didn’t see any. Of course, there are lots of things that could have easily been missed, viruses for example and anything that wouldn’t grow on a simple agar plate. I was definitely expecting more fun stuff to appear! Good job keeping those toes clean ‘lil guy!
So should you take your shoes off? I say yes, keep ‘em at the door and give anything moist a chance to dry out. Research also indicates that we are tracking pesticides into our homes (which can last for years).
Simpson, J. M., et al. "Characterization of fecal bacterial populations in canines: effects of age, breed and dietary fiber." Microbial ecology 44.2 (2002): 186-197
Nishioka, M. G., et al. "Foot transfer of lawn-applied pesticides from turf to carpet: comparison of semivolatile chlorpyrifos with nonvolatile chlorothalonil." Bulletin of environmental contamination and toxicology 68.1 (2002): 64-71.
Nishioka, Marcia G., et al. "Distribution of 2, 4-dichlorophenoxyacetic acid in floor dust throughout homes following homeowner and commercial lawn applications: quantitative effects of children, pets, and shoes." Environmental science & technology 33.9 (1999): 1359-1365.
All photos taken by me.