On the deadliest day for the nation yet in the novel coronavirus pandemic, it became apparent that Detroit, and Wayne County, may be emerging as a hot spot in the American outbreak.

New data released Thursday afternoon show that the City of Detroit and Wayne County have the highest number of confirmed coronavirus cases in Michigan — with 851 cases and 15 deaths in the city, and 538 cases and 11 deaths in the rest of Wayne County.

That means Wayne County ranks among the highest nationally in COVID-19 cases per capita — at 79 per 100,000 people. And in the city, it's far worse, with a per-capita rate of 127 confirmed cases per 100,000 residents. That compares to a statewide per-capita rate of 29 cases per 100,000.

And it's getting national attention.

"We are concerned about certain counties that look like they are having a more rapid increase" in COVID-19 cases, said Dr. Deborah Birx, the response coordinator for the White House Coronavirus Task Force during her Thursday evening briefing, specifically citing Wayne County as well as Cook County in Chicago.

"We have integrated all of our information to not only look at the cases we have today, but how they are moving, so we can alert FEMA (Federal Emergency Management Agency) to where we think the next potential hot spot is."

"All of the counties that I have mentioned, the hot spots are in urban areas or in the communities that serve that urban area," Birx said.

However, accurately modeling how widely the virus is spreading and sickening people in any community requires widespread testing and surveillance of both sick people and those who are asymptomatic, which isn't happening widely in the U.S. yet, Birx said, and makes it tricky to model how many people are likely to contract the virus.

She said nationally, about 550,000 novel coronavirus tests have been conducted. Of them, about 14% were positive.

"There is no model right now," Birx said, "I mean no reality that we can see that 60% or 70% are going to get infected in the next eight to 12 weeks. I just want to be clear about that."

The high number of COVID-19 cases in Detroit and Wayne County tell the story of a community with a disproportionately poor population, with high rates of asthma, diabetes, heart disease and high blood pressure — the very conditions that make it more likely for COVID-19 to cause severe symptoms, the very conditions that can end in death when this new coronavirus comes knocking.

"Part of what we're seeing in Detroit is there's such a high number of individuals who have those underlying conditions, who have the diabetes and the heart disease, who may have obesity," said Dr. Joneigh Khaldun, the chief medical officer for the Michigan Department of Health and Human Services, who formerly worked in Detroit as the city's health director.

"And so what you're seeing now is when you have really generations of concentrated poverty, what we call social determinants of health, that impact a place, a city like Detroit, when you have pandemics, it's going to hit those places harder."

It's also a story about lack of widespread coronavirus testing in the state, which may also explain why there seems to be such a disproportionate number of cases in Detroit and Wayne County.

Given that there's a lack of available tests for COVID-19 — 9,100 samples have been processed in a state of nearly 10 million people so far, Khaldun said — the priority for testing has been to test the sickest, most vulnerable patients, which stacks the deck against Detroiters.

Poverty, water shutoffs, and lack of access to accurate information about the fast-spreading virus play into its spread as well. One out of three Detroit residents lives below the poverty level, according to 2018 census estimates.

“We allowed a house of cards to get built and this pandemic is blowing it down,” said Dr. Abdul El-Sayed, health officer and executive director of Detroit’s department of health from 2015 to 2017.

“Detroit is the poorest major city in America,” he said.

“Around 50% of people in Detroit are Medicaid eligible, and there are very few clinics that even take Medicaid,” El-Sayed said. “There is high unemployment in the best of times, and in the worst of times, it’s substantially higher. People more likely to be working low-wage jobs" than salaried work with employer-based health benefits.

“And you have a situation where basic utilities are limited …” he said. “That it was happening so much before this ever hit set us up to be deeply exploited by this pandemic. What people need to understand about public health is to see how vulnerability makes us all vulnerable.”

And the health disparities are undeniable.

Michigan ranks sixth-highest among all the U.S. states in prevalence of asthma among adults, according to the state Department of Health and Human Services. Its 2019 report, Michigan Asthma Atlas, showed that 10.9% of adults in the state had asthma in 2016.

Who has asthma in Michigan is filled with racial and economic disparities that make certain populations more vulnerable in a COVID-19 outbreak, especially if their asthma is uncontrolled.

The disease is 29% more prevalent among Detroiters than Michiganders as a whole, and also affects African Americans, those who are poor and those without health insurance more than people who are white, wealthier and better insured.

The new coronavirus enters the body through the respiratory system — most often when a person with COVID-19 coughs or sneezes and droplets travel to another person's eyes, nose or mouth, according to the CDC. Transmission is also believed to occur when a person touches a contaminated surface and then touches their eyes, nose or mouth.

For people who have COPD, congestive heart failure, asthma or other diseases, "the lungs are already compromised in their ability to function normally," Dr. Nasir Husain, the medical director of infectious diseases at Henry Ford Macomb Hospital, told the Free Press for an interview in early March. "And then if you add on another health condition, which could be anything from coronavirus to the common cold or pneumonia, certainly it would be difficult for the lungs to deal with so many things."

About a million people in Michigan, or 12.4% of the state's population, have diabetes, according to the American Diabetes Association.

Obesity is also considered an underlying health condition that can reduce a person's lung and heart capacity, Husain said, and put them at risk for more severe illness if they were to contract COVID-19.

About 31% of Michigan adults are obese, according to the MDHHS, and 35% of Michiganders are overweight. In the city, lack of access to fresh produce also is an contributing factor for obesity, where high-calorie, high-sugar, high-fat food is more readily available than healthy food.

Detroit's coronavirus case numbers also tell the story of a city that still has residents without running water, whose service was shut off because they couldn't afford the bills. Without water, people can't wash their hands and are more likely to spread the disease because they're unable to maintain good hygiene.

"Clearly if people don't have water, they can't wash their hands in any kind of proper way," said Dr. Paul Kilgore, an associate professor at Wayne State University's Eugene Applebaum College of Pharmacy and Health Sciences

"And that population, of course, is going to be at risk of not having access to hand sanitizer as well, and they also are less likely to have access to good, accurate health education information.

"The concern I have right now is poor, the super vulnerable population," which includes homeless people, immigrants and undocumented people, "who also may be afraid to seek care and may wait to the last minute or may not go in to a hospital at all, and they will be transmitting the disease at home."

Although more than 1,400 Detroit households without water have, or are in the process of, having service restored, the virus was spreading long before the taps were turned back on.

Gov. Gretchen Whitmer said the large number of cases in the city and in metro Detroit also has to do with high population density.

"Like big cities everywhere, people live closer together," Whitmer said Thursday. "Spending more time in close quarters together, that's how the disease spreads. ... Scientists are telling us that this would sputter to a halt if we all froze where we are for 14 days. But the fact of the matter is more interaction is more spread, and the closer people live together, the more spread, and that is what happens in big cities across this country, around the globe."

But there are other factors, too, such as testing.

Dr. Betty Chu, associate chief clinical officer and chief quality officer for the Henry Ford Health System, said Wednesday that she wouldn't speculate on the high numbers in the city and Wayne County, but noted “the numbers do get reflected based on how much testing is being done.”

Bob Riney, president of healthcare operations and chief operating officer for Henry Ford, said the hospital system has a backlog of symptomatic patients who are waiting for testing, but as testing capacity continues to increase, he expects the numbers to change.

"Over the next few days you’ll get a lot clearer picture of the number of cases that we have in the metropolitan area and it may change where that density lies between Detroit or any of the other counties as testing goes online,” he said Wednesday.

Dr. Peter Gulick, an infectious disease specialist and associate professor of medicine at Michigan State University, agrees that there's likely a broad mix of factors that play into the numbers we're seeing now.

But it also could be that the data are starting to reveal that metro Detroit, with the city at the center, is becoming a hot spot for novel coronavirus — much like the metropolitan New York area, New Orleans, and communities in Georgia and Colorado, which have higher per-capita case numbers than Wayne County.

"That's my fear," Gulick said. "Because if you look at the location of all those cases, 86%, almost 90% of them are down in southeast Michigan. ... Detroit, that's the main epicenter, so to speak, where all these cases are."

One contributing factor that has yet to be explored, Gulick said, is the possibility of super-spreaders, or people who are shed more virus particles than others for reasons that aren't completely understood.

"That's kind of an unknown," he said, noting it is possible that some asymptomatic people who have novel coronavirus or those with very mild symptoms are spreading it widely in the community.

"The super shedders is a question nobody has an answer to and whether some of these mildly symptomatic people, could they indeed be ones that are shedding the virus more as well? That's a good question."

With most viruses, he said, patients with the most severe symptoms shed the most virus particles. But given that this is a new virus, much about it is unknown.

"This disease is extremely contagious. It can be extremely aggressive in a small population of patients," he said.

Whitmer said the key to stopping the spread of the virus is to stay home.

"This crisis is ramping up exponentially," she said.

"There is no cure, and there is no vaccine. We need to slow the spread of COVID-19. That's how we shorten the time that we will be fighting this crisis. Stopping the spread is really the only tool we have right now to keep our communities safe."

Contact Kristen Jordan Shamus: 313-222-5997 or kshamus@freepress.com. Follow her on Twitter @kristenshamus.