(CNN) Dr. Craig Spencer has worked as an epidemiologist in Africa and Southeast Asia and famously survived getting Ebola in 2014 after caring for patients in Guinea.

The coronavirus scares him.

Dr. Craig Spencer is urging people to take coronavirus seriously and to stay home.

Spencer is now the director of Global Health in Emergency Medicine at New York-Presbyterian/Columbia University Medical Center in New York City, which has become the epicenter of the US outbreak

He described a harrowing day in the emergency room in a lengthy Twitter thread posted early Tuesday morning.

Spencer wrote that he starts his day like many other workers by brewing a big pot of coffee because the coffee shops near the hospital are closed.

It ends with him taking his clothes off in the hallway of his apartment, avoiding his toddler until he can run to get a shower to "rinse it all away" before getting some family time for the first time in days.

The hours in between are filled with case after case of coronavirus, beginning when he walked into the ER at 8 a.m.

"Immediately struck by how the calm of the early morning city streets is immediately transformed," he wrote . The bright fluorescent lights of the ER reflect off everyone's protective goggles. There is a cacophony of coughing. You stop. Mask up. Walk in."

He writes that he is told about a patient who is receiving the maximum amount of oxygen but is still breathing fast.

He describes having "a long and honest discussion" with the patient and her family -- who are on the phone -- that she needs to go on life support before things get worse.

"You're notified of another really sick patient coming in. You rush over. They're also extremely sick, vomiting. They need to be put on life support as well. You bring them back. Two patients, in rooms right next to each other, both getting a breathing tube," he wrote . "It's not even 10 a.m. yet."

Afraid to take off his mask

He gets paged almost hourly with urgent messages:

"Stat notification: Very sick patient, short of breath, fever. Oxygen 88%.

Stat notification: Low blood pressure, short of breath, low oxygen.

Stat notification: Low oxygen, can't breath. Fever."

At some point, he realizes that it's the afternoon and he hasn't drank any water.

"You're afraid to take off the mask. It's the only thing that protects you. Surely you can last a little longer - in West Africa during Ebola, you spent hours in a hot suit without water. One more patient..." he wrote

Spencer eventually gets something to eat in the hospital cafeteria which is thankfully still open. He washed his hands twice, cautiously took off his mask and eats as fast as he can before rushing back to work.

"Nearly everyone you see today is the same. We assume everyone is #COVID-19. We wear gowns, goggles, and masks at every encounter. All day. It's the only way to be safe," he wrote . "Where did all the heart attacks and appendicitis patients go? Its all COVID."

When his shift finally ends, Spencer cleans everything he has before he leaves the hospital to walk home.

"Before you leave, you wipe EVERYTHING down. Your phone. Your badge. Your wallet. Your coffee mug. All of it. Drown it in bleach. Everything in a bag. Take no chances," he wrote . "Sure you got it all??? Wipe is down again. Can't be too careful."

Spencer says he feels" naked and exposed" as he walks down the deserted streets without a mask.

"The streets are empty. This feels nothing like what is happening inside. Maybe people don't know???" he wrote

Social distancing is 'the only thing that will save us'

As bad as the day was, Spencer expects it to get worse.

"Everyone we see today was infected a week ago, or more. The numbers will undoubtedly skyrocket overnight, as they have every night the past few days. More will come to the ER. More will be stat notifications. More will be put on a ventilator," he wrote

Spencer wrote that it's too late to stop the virus, but its spread can be slowed because "the virus can't infect those it never meets."

"Social distancing is the only thing that will save us now," he wrote . "I don't care as much about the economic impact as I do about our ability to save lives."

He ended the thread with a plea for people to take the pandemic seriously.

"You might hear people saying it isn't real. It is.

You might hear people saying it isn't bad. It is.

You might hear people saying it can't take you down. It can.

I survived Ebola. I fear #COVIDー19.

Do your part. Stay home. Stay safe.