When you step into the bathroom each morning, you might not expect to encounter a treasure trove of viral biodiversity. But according to a new study led by researchers at Northwestern University, your showerhead and toothbrush harbor hundreds of viruses, most of which have never been seen before.

Despite how unsettling that might sound, there’s no need to panic. These viruses, known as bacteriophages (or phages), are harmless to humans. They exclusively target bacteria, potentially holding the key to solving one of the most pressing medical challenges of our time: antibiotic-resistant infections.

A Viral Rainforest in Your Bathroom

In their study, microbiologists found over 600 different viruses living on 92 showerheads and 36 toothbrushes across the United States.

“The number of viruses that we found is absolutely wild,” said Erica Hartmann, the study’s lead author. “We found many viruses that we know very little about and many others that we have never seen before. It’s amazing how much untapped biodiversity is all around us. And you don’t even have to go far to find it; it’s right under our noses.”

Hartmann and her team were building on previous research that focused on bacteria living on these same surfaces. In this latest investigation, they sequenced DNA from swabs to discover just how many viruses were sharing the space. They found that each toothbrush and showerhead seemed to host its own unique community of viruses.

“There was basically no overlap in virus types between samples,” Hartmann said. “Each showerhead and each toothbrush is like its own little island. It just underscores the incredible diversity of viruses out there.”

More Than Just Harmless Tenants?

The bacteriophages detected are likely present on any moist surface in your home, including sinks and fridges. While their presence might seem benign, researchers are increasingly interested in phages for medical and biotechnological purposes. These viruses may eventually help to combat drug-resistant bacteria, which are becoming an increasing threat to global health.

Drug-resistant pathogens kill almost 1.3 million people around the world each year and contribute to the deaths of nearly five million others. A more recent estimate published in The Lancet suggests that more than 39 million people will die from antibiotic-resistant infections between now and 2050.

Bacteriophages work in two key ways: they either destroy bacteria by hijacking the bacterial machinery to replicate themselves or integrate into the bacterial genome, altering the behavior of the bacteria. Both mechanisms could provide novel ways to target harmful bacteria in medical settings, or even to keep our plumbing systems clean.

“We could envision taking these mycobacteriophage and using them as a way to clean pathogens out of your plumbing system,” Hartmann explained. “We want to look at all the functions these viruses might have and figure out how we can use them.”

What This Means For Home Hygiene

While these findings might stir thoughts of grabbing the nearest disinfectant, Hartmann offers a different perspective. “The more you attack them with disinfectants, the more they are likely to develop resistance or become more difficult to treat,” she warned. Instead, she suggests embracing the microbes that live with us, noting that the vast majority of them are not harmful. Simple cleaning methods, such as soaking showerheads in vinegar and regularly replacing toothbrushes, are more than sufficient to maintain good hygiene.

In a world where antibiotic resistance is on the rise, the discovery of hundreds of unknown viruses in our homes could be a small but significant step toward finding new solutions. It turns out that the next breakthrough in healthcare might be as close as your bathroom sink.

The findings were reported in the journal Frontiers in Microbiomes.