Researchers say there are 500 forms of bacteria that can travel to 50 percent of your office in just four hours.

Do you avoid your office kitchen?

Wipe down the toilet seat in the office bathroom?

Shudder when your colleague sneezes?

Some may call you a hypochondriac, but your fears may in fact be justified.

It turns out our offices are full of bacteria.

A 2012 study that examined offices in Tucson, New York, and San Francisco found that there were 500 forms of bacteria in the average office environment.

And that bacteria travels fast.

A 2014 study that examined the spread of viruses in workplace settings, found that the germs from a single sick individual had spread to 50 percent of surfaces and employees within four hours.

“We conducted a study in the workplace because we know this is a site where many people continue to come to work even when they’re sick,” Kelly Reynolds, PhD, associate professor of environmental health sciences at the University of Arizona and lead author of the study, told Healthline.

“Workplace environments typically include numerous sites where people congregate, such as in the shared kitchen, shared copy room, bathrooms, and shared conference rooms. These shared sites act as central germ transfer stations. As workers move about the office and touch surfaces they leave behind germs picked up along the way.”

According to Reynolds, adults can touch up to 300 surfaces per hour making the spread of germs in the workplace an almost inevitable reality.

Norovirus is the most common cause of severe gastroenteritis in the United States.

The Centers for Disease Control and Prevention (CDC) estimate that norovirus causes about 20 million acute cases of gastroenteritis every year.

Those illnesses lead to nearly 2 million outpatient visits and 400,000 emergency department visits per year.

Charles Gerba, PhD, a professor of microbiology and environmental sciences at the University of Arizona, has spent decades studying germs.

In 2014, he conducted a study to see how easily norovirus was able to spread in an office environment.

Gerba and his colleagues used a bacteriophage (a virus that infects other bacteria but not humans) called MS-2. MS-2 is similar in size, shape, and resistance to disinfectant, as the norovirus.

At the start of the day it was placed on commonly touched surfaces within an office building such as doorknobs and tabletops.

Within just two to four hours, 40 to 60 percent of other surfaces in the office were contaminated with the virus.

But Gerba says use of basic hygiene practices could help curb the spread of germs and he, himself isn’t worried.

“Since doing the work on germ movement in offices and interventions to reduce the spread of germs in this environment, I feel confident that I can easily significantly reduce my risks. Just use of a hand sanitizer and disinfectant wipes can reduce your risk of infection by up to 80 percent,” he told Healthline.

In the industrialized world, millions of people spend around 90 percent of their time indoors and Gerba says the pressure to come to work even when ill is only making things worse.

“Work has changed so much in the 21st century. We spend more time indoors than any generation in history, and more of us work in offices than ever before,” he said. “During the cold season we have found that one-third of the surfaces in an office will have the cold virus on it. One of the major problems is many people come to work ill, especially with colds, and spread it around the office. This is called presenteeism, which has a significant impact on office productivity. It is now believed that presenteeism costs companies more in lost productively than absenteeism.”

As for the germ hotspots in the office, the areas with the most germs may surprise you.

The bathroom is among the cleanest places in the office.

“The toilet seat germ-wise is usually the cleanest object in a restroom because so many people (48 percent of American women) will wipe it or place toilet paper on it before use. Also, disinfectants are usually used by cleaning crews on the toilet seat,” Gerba said.

If you’ve ever used your sleeve or a hand towel to open the bathroom door after washing your hands you can probably skip that.

Gerba’s studies have found at least 70 percent of people wash their hands in the restroom. The handle on the outside of the door actually holds more germs than the handle inside the bathroom.

Areas you should watch out for are where you may be spending the bulk of your time.

“Hot spots in the office are in order: desk phones, desktops, computer keyboards, computer mouse, and photocopier buttons. I do not think most people clean their desktops till they stick to them,” Gerba said.

Things aren’t much better where you prepare lunch or grab a cup of coffee.

“The coffee pot handle in a shared kitchen was the most commonly contaminated site. Refrigerator and microwave handles were also hot spots,” Reynolds told Healthline.

But Reynolds and Gerba say there’s no need to panic or vow to never enter your office kitchen again.

“Most of the cold, flu, and diarrhea-causing organisms likely to spread in the workplace do not cause serious illness, but a few simple practices can significantly reduce your chances of getting ill,” Reynolds said. “We should not be fearful, just more aware of the control we do have for improved health.”