Fear is rising in China and beyond as the deadly coronoavirus continues to spread within China and across global borders.

The outbreak started in Wuhan, a city in central China, which is why many people refer to the illness as the Wuhan virus. Related to SARS and MERS, the disease works its way into lungs, where it can cause symptoms like coughing, fevers and trouble breathing. Older patients have been the most at risk, since their compromised immune systems have allowed coronavirus to pave the way for conditions like pneumonia.

So far, at least 850 people have caught the disease, and at least 26 people have died, though those numbers are spiking sharply and likely will have increased by the time you read this. Most of the fatal cases were in older patients, but at least one man in his 30s has died from the virus. At least two cases have been confirmed in the U.S., but officials reported that both will likely recover.

China has put extraordinary measures into place to stop the spread of the disease. Unfortunately, this weekend is the celebration of the Lunar New Year, a time when millions of people travel to celebrate the holiday with their families in China. For some families, it’s the only time of year they can see each other, and many have put in extra hours to be able to afford the trip.

But this year, China has issued travel restrictions in several provinces, meaning that about 35 million people may not get to see their families. While it’s for the best to avoid a global health crisis, it’s also set to be a heartbreaking and anxious holiday for many.

Not much. That’s a common problem when it comes to global outbreaks. The more scientists understand about a disease – where it starts, how it spreads, how long it takes to show up after infection, how best to treat it – the more they’re able to stop outbreaks dead in their tracks.

But when a new disease hits the scene, even one related to previous diseases like SARS, scientists have to work super fast to test lab samples and evaluate patients to figure out how to slow it all the way down. Of course, science has advanced since the time of historic outbreaks like the Black Death, various cholera outbreaks and the 1918 flu pandemic.

Now, we know much more about the spread of disease and understand the importance of, for instance, washing our hands after coughing, or avoiding water sources that could be contaminated.

But we also live in a much more global world than people in the past. Thanks to the relative ease and affordability of travel now, coronavirus has had the opportunity to spread to Nepal, Vietnam, Singapore, Japan, South Korea, Taiwan, Thailand, and the U.S., all in under a month. Now, scientists don’t have to rely solely on their smarts to get ahead of the disease and figure out how to squash it. They also have to rely on a wide variety of global governments to agree to their suggested preventive measures – and then enforce them.

In the case of the coronavirus, researchers have offered a few theories as to how it started. One was snakes, though now they think it could have originated with bats. And no offense to bats, but those little upside-down-hangers have been responsible for quite a few outbreaks. Remember Ebola? That was likely bats. SARS, too.

But it’s not always the poor bat’s fault. They’re born with a natural immunity to many diseases, which means they can pick them up and pass them along without ever getting sick themselves. When they interact with the world around them – doing everyday things like eating insects, looking for shelter in dark, cool places – they come into contact with the animals that can pass along disease.

The movie Contagion demonstrates it all pretty perfectly. The movie deals more with how authorities respond to a deadly pandemic, but the end sums up how Gwyneth Paltrow became the dreaded Patient Zero: A bat has to look for a new home when humans chop down its tree in the dead of the night. It grabs a piece of fruit for nourishment, then finds new shelter inside a factory where pigs are being slaughtered for food. When the bat drops a piece of that fruit, one of the pigs finds it and scarfs it down, thus becoming infected. That pig gets sent to a restaurant, and when Gwyneth asks to meet the chef, he shakes her hand without washing it first. When she gets on a flight from Hong Kong to L.A. the next day, she doesn’t realize that everyone she’s coming into contact with could be getting infected, just like they don’t realize that everyone they come into contact with could get infected, and so on. A few days later, she’s dead, and a global pandemic is underway.

Not all outbreaks are so extreme or deadly, and not all diseases animals (or plants) pick up can be transferred to humans. But the scenario does demonstrate how easy it is for a disease to take off before people even know how vicious it will be, as well as how many controls must be in place to stop it once it’s raging.

That’s why one of the most important things you can do during an outbreak is follow official guidelines. Listen to warnings like travel precautions and preventive measures, even if you think they’re a bit extreme. It could help save a life.