Cells from a diseased brain.Centers for Disease Control and Prevention

Of all the places you expect to be safe from germs, you wouldn't think to find bacteria on surgical tools used in an operating room.

Last week, however, the Massachusetts Department of Public Health released a statement over five patients who underwent surgery at a Cape Cod Hospital who were exposed to a fatal brain disease due to being exposed to the same potentially contaminated medical equipment. The disease, Creutzfeldt-Jakob disease (CJD), causes patients to "show signs of memory loss and cognitive difficulty early on," according to CNN, and is almost always fatal.

Though the hospital did conduct normal sterilization procedures on all of their equipment, it evidently was not enough to kill the disease proteins and prevent the transmission of CJD.

Ahead of the start of cold and flu season, the episode is a reminder that germs can be lurking anywhere, often where we might not expect them.

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Beware your doctor's tie.Corbis Images

Given how many patients pass through hospital and doctors' offices, the presence of germs at these sites shouldn't come as a shock. What might be surprising, however, is just how much bacteria can be found on doctors' neckties, according to research conducted at New York Hospital Queens in 2004.

Nearly half of ties worn by clinical practitioners tested positive for disease-carrying organisms, which could then be transmitted to patients. A spokesperson for the British Medical Association suggested the fact that neckties are a garment rarely, if ever washed may be contributing to the problem.

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Smartphones may be smart, but they're usually not clean.Corbis Images

Considering that at least some fraction of you out there are reading this slide while sitting on the toilet, it should come as no surprise that your phone could be a hot spot for germs.

In fact, you might want to think twice before putting your phone against your face to take a call. As noted in a 2012 Gizmodo article ominously titled, "Your Smartphone Is Basically a Poopstick," researchers at HML Labs found that smartphones tested positive for "abnormally high" levels of coliforms, a bacteria indicating the presence of fecal material.

The study's authors attributed the high level of contamination to the dependence on smartphones almost as another appendage as well as the lack of effective cleaners for these devices.

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Items in a fridge are kept cool to ward off germs, but some germs can still thrive.Samsung

The refrigerator is the place where food is supposed to be safe from spoilage, but in fact can be a haven for germs. Improperly packaged food and damaged containers can leak into the fridge and leave behind bacteria that sticks around even after the food is gone.

A study conducted in 2011 by researchers at Microban Europe found high levels of potentially dangerous bacteria, including E.coli, salmonella and listeria. Researchers didn't even test beyond the salad drawers to find these bugs.

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Many different hands touch grocery carts.Getty Images

Wondering how so much bacteria can get into a refrigerator? Consider the last time you were shopping. Did you push a cart or carry a basket with you? If so, then likely with each food item you picked up or handled, you introduced germs from that cart or basket handle to that product.

In a study conducted in 2011 by University of Arizona researchers, half of carts tested positive for E. coli and 72 percent turned up positive for fecal bacteria.

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Wash your hands before dinner, then you may want to again after touching the menu.Getty Images

Too grossed out by the idea of what might be lurking in your refrigerator to eat in tonight? A restaurant probably wouldn't be much better, particularly when you consider all the germs that are lurking just on the menu.

The average bacteria count on a restaurant menu is about 185,000, according to ABC News. In fact, as one health expert explained, there are about 100 times more bacteria on the menu than there are on a typical toilet seat in the restroom.

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Washing machines may clean, but they don't always disinfect.Corbis Images

Your washing machine is supposed to be an ally in the war on germs, taking all your dirty clothes and in short order making them clean again.

But used improperly, a washing machine can in fact spread disease agents like E. coli bacteria. The problem is that many washers don't get hot enough to reach the point at which they can kill bacteria. As a result, while they can clean clothes of dirt and stains, they don't really disinfect.

According to microbiologist Chuck Gerba of the University of Arizona, one in four washing machines is contaminated, based on a study he conducted. To disinfect washers, he recommends running it empty with just a cup of bleach every two or three wash cycles.

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Lemon may be refreshing in your drink, but not always clean.iStockphoto

Lemon and lime wedges can add a bit of tang to your drink, but they also can toss in a splash of disease-carrying pathogens. A study published in the December 2007 issue of the Journal of Environmental Health found that nearly 70 percent of lemon wedges sampled contained E. coli as well as fecal bacteria, according to NBC News.

Lemon juice possesses antimicrobrial properties, and any alcohol in a drink could also kill bacteria, so it remains unclear whether the presence of bacteria in lemon wedges poses any kind of health hazard.

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ATM transactions may be quick, but germs still find time to infect.redspotted/Creative Commons

Given how quickly ATM transactions occur -- or at least they do for everyone except the guy right in front of you in line -- you'd think ATMs might well be clear of too many germs. In tests conducted by the Kimberly-Clark Corp. in 2011, ATMs came in fourth for public places tested for disease-carrying agents, behind gas pump handles, mailbox handles and escalator rails, according to Computerworld.

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Your keyboard probably hosts more germs than your toilet.Corbis Images

Considering that any office worker has their hands on a keyboard and mouse throughout the work day, a little dirt and grime buildup on computer equipment might be expected. What the average desk jockey probably doesn't know is just how many germs are hiding between every key or button. In fact, they're worse than toilets.

In a study conducted in 2008 in the United Kingdom, tests on keyboards in a typical office environment turned up E. coli and staph bacteria, among other pathogens. Worse still is the fact that most office workers may never bother to properly disinfect their equipment.

So if you suddenly feel the urge to clean your work space or, better still, take a sick day, we'll back you up.