Anyone that’s taken a microbiology course can attest: there are some downsides to knowing that microbes coexist with human beings, and that they exist everywhere and all the time. You may learn about only a small fraction of the pathogens that exist, and still, it's enough to give anyone the creeps.

Microbiology majors are all-too-familiar with the facts. Anyone that has some knowledge of the subject, however, experiences similar phenomenon:

That feeling when you are taught disconcerting fun facts such as: there are more bacterial cells in the human body than human cells. Or how there can be over a hundred different kinds of bacteria just on a person's hands.

If learning about normal bacteria that exists in/on the body is bad, learning about pathogens is even worse. Suddenly, you're hyper-aware of every disease you could be contracting. Not to mention, every pathogen that sits in your body, dormant but still capable of becoming active.

...and you know exactly how those pathogens kill you; you know how they invade your body, kill your cells, and spread through your organs. Not to mention, all the symptoms that accompany the disease (like preventing any muscle relaxation, which can lead to death by suffocation—thanks, tetanus.)

Microbiology even robs you of simple pleasures. For instance, if you weren't vegetarian before, learning about the bacteria in meat could inspire a dietary change. Next time you get a partially cooked piece of meat—hello, Salmonella.

You've never been so compulsive about washing your hands; really, disinfecting everything you touch doesn't sound like such a bad idea.

Nothing gives you a sense of ultimate doom like learning about the ever-increasing rates of antibiotic resistance. Ironically, many patients in hospitals contract infections they didn't have before because of all the hard-to-kill antibiotic-resistant bacteria.

And finally, nothing could inspire someone to be avoid physical intimacy like learning about each and every STD.

But in the end, microbiology is still fascinating and you probably won't regret taking the class. (Probably.)