Toothbrushes and shower heads: they are teeming with viruses

 

Hygiene Tips to Combat Viruses

Forget tropical rainforests and coral reefs. If you’re searching for a biodiversity hotspot, look no further than your bathroom, home to a surprising microbial jungle. In a recent study by Northwestern University, microbiologists discovered that showerheads and toothbrushes host an incredibly diverse range of viruses, most of which are previously unknown to science. While this may sound alarming at first, the study shows that the discovery is actually good news. Here's why.

A Surprising Variety of Viruses

You’ve likely heard the urban legend that bathroom toilets contaminate toothbrushes with fecal matter. However, the new study, published on October 9 in Frontiers in Microbiomes, builds on previous research led by Erica Hartmann, a microbiologist at Northwestern University. Her earlier findings revealed that the majority of microbes found on toothbrushes come from the user’s mouth rather than toilet aerosols.

This research sparked further interest. “We wanted to understand which microbes live in our homes,” Hartmann explains. “Surfaces like walls and tables aren’t very friendly environments for microbes, but they thrive in places with water. So naturally, we looked at showerheads and toothbrushes.”

Analyzing Showerheads and Toothbrushes

The research team collected DNA samples from these items, sequencing them to identify the viruses present. They found 614 different viruses across 92 showerheads and 34 toothbrushes in the U.S. Interestingly, no two samples were identical — each object seemed to host its own unique viral community, with many viruses likely unknown to science.

“The sheer number of viruses we found is astounding,” says Hartmann. “We discovered many viruses we know almost nothing about and many others we had never seen before. It’s incredible to realize how much unexplored biodiversity surrounds us, and we don’t even have to leave our homes to find it.”

Better News Than It Seems

Though the idea of viruses on your toothbrush might make some people uneasy, the researchers emphasize that these findings are not a cause for concern. "Microbes are everywhere, and the vast majority of them pose no threat to us," Hartmann reassures. Most of the viruses found in the study were bacteriophages — viruses that exclusively infect bacteria. These phages are harmless to humans and specifically target mycobacteria, a group of bacteria responsible for diseases like tuberculosis, leprosy, and some chronic lung infections.

Bacteriophages act in two ways: they either destroy bacteria by using them to replicate or integrate into bacterial genomes, modifying bacterial behavior.

Significant Health Implications

With an estimated one trillion microbial species on Earth — 99.9% of which remain undiscovered — this type of research is essential for advancing our understanding of microbiology.

Hartmann also suggests practical applications for these viruses: “We could use mycobacteriophages to clean pathogens from plumbing systems.” Her team aims to explore the full potential of these viruses and how they might be used.

This research could also aid in developing treatments against antibiotic-resistant superbugs. Scientists are actively working on phage therapies, where viruses complement or replace traditional antibiotics to target resistant bacteria. Currently, drug-resistant pathogens kill about 1.3 million people annually and contribute to nearly five million deaths. A recent estimate from The Lancet predicts that over 39 million people could die from drug-resistant infections by 2050, underscoring the importance of these findings.

Practical Hygiene Tips

To maintain good hygiene, Hartmann recommends cleaning showerheads with soap and water or soaking them in vinegar to remove calcium buildup. She also advises regularly replacing electric toothbrush heads and traditional toothbrushes. However, she cautions against using antimicrobial toothbrushes, which could promote the growth of antibiotic-resistant bacteria.

“Microbes are everywhere, and most won’t harm us. The more we fight them with disinfectants, the more likely they are to develop resistance and become harder to manage. We just need to learn to coexist with them,” Hartmann concludes.

You can read the study in detail here.