There is a growing, concerning movement undermining one of the most well established scientific theories there is: germ theory, the idea that germs—like viruses and bacteria—cause disease.
But it’s subtle.
Outright denial of germ theory is still a fringe idea: very few deny that viruses and bacteria exist. Rather, it’s the effect of germs—whether germs are the true cause of an illness—that is increasingly being called into question.
What germ theory is and isn’t
When germ theory was first proposed in the 1800s, scientists didn’t have the modern scientific tools we have today, and there was genuine debate over how infectious diseases like cholera were transmitted. Some thought it was microscopic germs, while others thought it was “bad vapors” (miasma theory). But that debate has been long settled. Microscopic germs like Vibrio cholerae (the bacteria that causes cholera), measles, influenza, and polio all cause infections that make people sick
Of course, there is more to germs than just disease. Some germs are good for us—like the many germs that make up the microbiome in our gut. And some germs cause disease only some of the time, like the MRSA bacteria that I am almost certainly colonized with as a healthcare worker. And sometimes, other health conditions—like those with diabetes or conditions that weaken the immune system—make people more susceptible to infectious germs.
Germ theory does not say all germs are bad, nor does it say germs are responsible for every disease known to humans, nor does it say that any exposure to a germ is a guarantee of illness. It says that certain germs can cause infections that make people sick. And when that happens, the germ really is to blame.
A new subtle form of germ theory denial
But this idea is starting to be rejected and replaced with a new, inaccurate view of why infections happen and what we should do about them.
This new version of germ theory denial still acknowledges that germs are real, but says they’re not all that much of a threat for a healthy individual, and not the real problem causing disease. Instead, when someone catches an infection, the person’s immune system and lifestyle are blamed—an unhealthy diet, lack of exercise, exposure to “environmental toxins,” or underlying conditions are allegedly the “true” cause of disease because they damaged the immune system. (continued)