10,000 new viruses found in babies’ dirty diapers: scientists

Who knew baby poo could be so informative?

Danish researchers collected hundreds of dirty diapers from babies and found thousands of previously unknown viruses.

Scientists were already aware that the gut’s microbiome plays a role in the onset of chronic illnesses — such as asthma, ADHD and diabetes — later in life, yet have only just begun to parse the many viruses contained there.

Now, a new study published in Nature Microbiology can confirm that the baby gut contains some 10,000 viral species — 10 times more than the number of bacterial species in the average child.

The newly identified viruses can be grouped among a total of 248 viral families, 232 of which were not previously known until now.

“This means that, from early on in life, healthy children are tumbling about with an extreme diversity of gut viruses, which probably have a major impact on whether they develop various diseases later on in life,” professor Dennis Sandris Nielsen told Phys.org.

To better understand the early days of gut development, a multidisciplinary team of researchers analyzed the fecal makeup of 647 healthy 1-year-olds who had been enrolled in long-term asthma and chronic inflammatory disease study based in Denmark.

A vast majority — 90% — of the viruses detected among the diaper contents were bacteriophages, viruses that attack potentially harmful bacteria. Scientists call these viruses “allies” because they don’t cause illness or disease.

The remaining 10% are eukaryotic, which instead attach themselves to human cells — for better or worse, perhaps. Nielsen explained that this would mean the average child is infected with 10 to 20 of these viruses at any given moment, “which apparently doesn’t make them sick.”

“We just know very little about what’s really at play,” Nielsen continued. “My guess is that they’re important for training our immune system to recognize infections later. But it may also be that they are a risk factor for diseases that we have yet to discover.”

Shiraz Shah, the study’s first author and a senior researcher at Copenhagen Prospective Studies on Asthma in Childhood, said they think viral loads are higher in the infant’s gut because the immune system is still maturing, and needs a militia of bacteriophages as a backup defense.

“Our hypothesis is that, because the immune system has not yet learned to separate the wheat from the chaff at the age of one, an extraordinarily high species richness of gut viruses emerges, and is likely needed to protect against chronic diseases like asthma and diabetes later on in life,” Shah elaborated in a press release.

Nielsen noted the environment also plays a part in the plethora of viruses.

“Our gut is sterile until we are born. During birth, we are exposed to bacteria from the mother and environment,” he explained. “It is likely that some of the first viruses come along with these initial bacteria, while many others are introduced later via dirty fingers, pets, dirt that kids put in their mouths and other things in the environment.”

Their research helps to inform why so many chronic diseases, including arthritis and depression, have an inflammatory component.

Said Shah, “The immune system is not working as it ought to — which might be because it wasn’t trained properly. So, if we learn more about the role that bacteria and viruses play in a well-trained immune system, it can hopefully lead us to being able to avoid many of the chronic diseases that afflict so many people today.”