A podiatrist and an infectious disease specialist weigh in on a mom's social media warning gone viral.

A mother’s warning about back-to-school shopping has gone viral after her daughter developed a serious infection and nearly died after trying on shoes at a store in the United Kingdom. The 4-year-old child wore sandals to the store and was barefoot while she tried on other shoes, her mother said, which may have allowed her to pick up a dangerous infection.

“For all parents please put socks on you’re [sic] children while trying new shoes on,” Jodie Thomas wrote on Facebook. “I’m guilty not doing it for mine and myself, but this can be the outcome infection spreading throughout the body.” She posted several photos of her daughter in a hospital bed, with a visibly infected wound at the base of her pinky toe.

MetroUK reported that Thomas took her daughter to the doctor’s office the day after their shopping trip, “when she started crying in agony.” The doctor noticed that 4-year-old Sienna’s foot was infected, and “used a pen to draw a line around where the infection had spread,” according to the news site.

The following day, Thomas drove her daughter to the hospital when she saw that the infection had spread up her leg. Sienna also had a fever, and she was “shaking and twitching,” her mother told MetroUK.

Doctors diagnosed Sienna with sepsis, a dangerous complication of an infection that enters the bloodstream that can quickly become fatal. The hospital staff thought they would have to operate, said Thomas, but thankfully they were able to “drain all the pus from her leg and say the antibiotic drip will do the job.” Sienna was released from the hospital a few days later.

For anyone who’s ever tried on shoes in a shoe store—with or without using those little nylon footies—this story sounds like all of our greatest paranoid fears come to life. But can a deadly infection really occur just because you’re sharing shoes with a stranger? And what about all of the other gross places where we tend to go barefoot—like the beach, the airport security line, or in a public shower, for example: Are we at risk there too?

To get a better sense of the real dangers here, Health spoke with both a podiatrist and an infectious disease specialist—both of whom have plenty of experience with bacteria and less-than-hygienic scenarios. Here’s what they say are the real lessons we should learn from this story.

What is sepsis, and how does it occur?

Sepsis is what happens when a bacterial infection enters the bloodstream, causing inflammation to spread throughout the body. Limbs can quickly become damaged and may have to be amputated. And if the infection reaches vital organs, those organs can shut down and a patient can die.

Sepsis can occur after an illness, but it can also occur when bacteria enter the body through an open wound. And that’s the most important part of Sienna’s story, says William Schaffner, MD, an infectious disease specialist at Vanderbilt University Medical Center: It’s likely the girl had some type of abrasion on her foot while she was trying on shoes.

“That abrasion provided a location for bacteria to enter her body,” says Dr. Schaffner. The bacteria then entered her bloodstream, he says—a rare but not unheard of complication.

Of course, we all get small cuts and bug bites, and very few of us will ever develop dangerous infections. “About 99% of the time, those wounds will heal without any difficulty,” says Dr. Schaffner. “But occasionally, they will cause further problems.” Children, older adults, and people with weakened immune systems are more at risk, he adds, but both infections and sepsis can also happen to perfectly healthy people.

Going barefoot can be dangerous—but not for the reason you might think

So where did this dangerous bacteria come from? Surprisingly, Dr. Schaffner says, it probably wasn’t from the shoes in the store. It’s far more likely, he says, that Sienna became infected with bacteria she had carried on her own skin.

That’s because all of us carry numerous strains of bacteria in and on our bodies at all times, he says. Many of those bacteria, like Group A streptococcus, live in our noses and throats and on our skin and can be completely harmless. But if those same bacteria make their way into an open wound—even something as small as a bug bite or a blister—they can cause serious infections.

“It can be breathed out and get on a person’s fingers, and then if they’re touching their blister it can get beneath the surface,” Dr. Schaffner told Health back in 2017, when a 32-year-old hiker nearly died from an infected blister. (In that case, doctors confirmed that streptococcus was to blame. In Sienna’s case, no specific bacterium has been named in news reports.)

“If we take cultures of all of our feet, 100% of us will have bacteria on them at the present time,” says Dr. Schaffner. “So let's not implicate the shoe or the shoe store as the source of the bacteria, but rather let’s focus on the important thing—which is to pay attention any time, anywhere we have a break in the skin.”

In other words, says Dr. Schaffner, going barefoot can expose your feet to more bacteria than usual—but it’s not likely any more dangerous than the bacteria you’re already carrying around yourself. The bigger risk, he says, is leaving yourself vulnerable to sharp objects (like shells on the beach) or friction (like new shoes rubbing against bare feet) that could create an abrasion or irritate an already existing one.

Would socks have helped?

Sienna’s mom is warning parents on Facebook to “carry a pair of spare socks” while shopping for shoes with their kids. And while Dr. Schaffner isn’t convinced that Sienna’s infection came from the shoes she was trying on, he does agree that wearing socks in this scenario is a smart move.

“It’s possible that she got this abrasion while trying on shoes,” he says. (Just think about how quickly you can develop blisters trying to squeeze into an ill-fitting pair.) “If that’s the case, wearing socks likely would have prevented that friction and prevented the abrasion in the first place.”

For that reason, he’s all in favor of wearing socks while shopping for shoes. Even those thin nylon foot protectors are better than nothing, he says.

Grace Torres-Hodges, DPM, a podiatrist in Pensacola, Florida and a spokesperson for the American Podiatric Medical Association, agrees that socks are a good idea while trying on shoes that other people have worn. There’s no way of knowing where Sienna’s infection came from, she says, but it’s not a stretch to say that shoes can harbor all sorts of unhealthy microbes.

“Bacteria can lead to cellulitis, fungus can lead to athlete’s foot or nail infections, and viruses can lead to warts,” she says. “When you see commercials for Clorox or Lysol about what’s living on surfaces, those same germs can absolutely live in shoes.”

To get our top stories delivered to your inbox, sign up for the Healthy Living newsletter

How else can we protect ourselves?

The biggest takeaway to be learned here, says Dr. Schaffner, is that life-threatening infections can happen to anyone, and to pretty much any type of wound. “That’s why it’s important to pay close attention, clean the wound with soap and water, and put a bandage on it to protect it from infection or further irritation,” he says.

If a cut, a blister, or an insect bite becomes red, swollen, or develops a pussy discharge, see a doctor right away, says Dr. Schaffner. Even then, chances are it’s a local infection that can be treated quickly with antibiotics—but make sure to tell your doctor if you’re experiencing any strange symptoms that could indicate a more widespread problem.

“Obviously, we undertake activities every day that put our feet at risk of abrasions,” Dr. Schaffner says, “from walking on the beach or doing carpentry around the house.” Injuries and abrasions are bound to happen, he adds, “so the lesson is to clean them out and watch them carefully.”

Living in a beach community, Dr. Torres-Hodges sees a fair amount of barefoot activity. “As long as the skin is intact, I don’t have much of a problem with it,” she says. “But if you want to be safe, any type of barrier can be helpful, whether it’s socks, shoes, or even flip-flops.”

Taking care of your feet is also important, she adds. “Your skin is the greatest barrier against any kind of infection, which is why we’re so particular about watching for areas where there is rubbing or calluses, or dry skin that could crack and break open."

Washing your feet regularly—and drying them well, including between the toes—can help keep skin healthy, Dr. Torres-Hodges says. Finally, make it a routine to check your feet regularly for wounds, calluses, or irregularities, and talk to your doctor if you notice anything out of the ordinary that’s not going away on its own.