Now that Major League Baseball has a start date for its pandemic-shortened season, it faces hard realities in markets where the coronavirus is spiking, notably Houston, where a top health official says he might object to games if current trends aren't reversed -- and soon.

The rate of coronavirus cases is rising in 15 of 27 U.S. markets that have teams, with significant surges in Phoenix and Houston, according to COVID-19 Case Mapper, a Stanford University-led collaborative project tracking national trends. The quickening spread increases pressure not only on MLB's plan to protect players and staff but also on government officials who could shut down gatherings, including baseball.

In Texas on Friday, Gov. Greg Abbott reimposed limits on businesses he reopened in May. His order closes bars and limits restaurants to 50% capacity. In California, Gov. Gavin Newsom ordered a county adjacent to San Diego back into stay-at-home mode Friday. In two other hotspot states, Florida and Arizona, governors are pushing forward with their reopening plans.

Abbott's office did not respond to questions about how baseball could be affected. His order, which says outdoor gatherings of 100 or more people "must be approved by local governments," appears to exempt professional and collegiate sports. But Dr. David Persse, the city of Houston's public health authority, told ESPN he will not be shy with his opinion if he deems it too dangerous for MLB to proceed.

"If the public's health is threatened, I will take a stand," Persse said. "From an operational standpoint, I find myself in the position where I'm going to have to be the one, that if I think it's going in the wrong direction, to make a stand."

According to the Texas Medical Center, the rate of positive coronavirus tests for the Houston region -- at 3% early this month -- hit 14% this week. The medical center, which houses about 70% of beds in intensive care units in the metro area, reported that its usual allotment of 1,330 beds, not including surge capacity, was full.

"That kind of tells you that the virus is spreading rapidly," Persse said. "I want us all to do the right thing and for the right reasons, and I'm trying to be realistic about it."

In Arizona, home to the Diamondbacks, Gov. Doug Ducey holds the authority to restrict sports and other activities. As of Friday, he had not moved to do so. An official in Maricopa County, where Phoenix is located, told ESPN this week the public health department had not been asked to review MLB's 101-page safety plan.

"The department has not communicated with the D'backs," the official wrote in an email. "And honestly, doesn't have time to review reopening plans for any business."

In a statement to ESPN on Friday, MLB reiterated that it will resume nationwide "only when it is safe to do so and consistent with public health concerns."

"For us, this means that, at a minimum, we will play in a particular location only when we have approval from all relevant governmental authorities," the statement read. "To date, all governmental authorities have been favorably inclined to allow play, at least in empty stadiums, based on our extensive protocols. This situation may change as developments with respect to the virus occur. If and when that happens, we will make adjustments to comply with any change in governmental policy.

"Independent of any governmental regulation, MLB will continually monitor the developing course of the pandemic with our experts. We will consult with the Players Association and will make operational decisions with the safety of our players and staff as the foremost consideration."

A senior MLB source also told ESPN that if baseball and government officials decide it's unsafe to play in a hotspot city, teams will be moved to other ballparks.

Will Humble, executive director of the Arizona Public Health Association and the former state health director, said the situation deteriorated quickly after the state's stay-at-home order expired May 15. Now, he said, "we are on New York's growth curve in terms of cases."

"It's bad, and in my opinion, we are going to run out of hospital capacity, existing non-surge capacity by Fourth of July, and we'll be in surge status," Humble said.

Still, he said he isn't concerned that teams playing in empty stadiums could further jeopardize public health, assuming everyone follows safety protocols and teams control infections.

"I think it's a threat to worker safety for the players and the coaches and stuff, but I don't have a concern that it's going to cause Arizona to go over the cliff. We're doing [that] fine on our own," Humble said.

Florida, which has teams in Miami and St. Petersburg, registered nearly 9,000 new coronavirus cases Friday, its highest daily total to date.

"I don't think it's changed my mind of having games here," said Miami-Dade County Mayor Carlos Gimenez, who added that the county's health resources aren't stressed now. "We have hundreds of ICU beds. We have thousands of critical care beds. We have the ability to add more, pretty quickly."

In California, rates of infection vary widely, with the hardest-hit regions in the southern part of the state, home to the Angels, Dodgers and Padres. But the hospital systems in counties housing those teams, as well as the Giants and Athletics to the north, are not under the same stress as those in Phoenix or Houston.

Persse and other health officials say Houston is on pace to exhaust hospital capacity at about the same time MLB has scheduled Opening Day -- on or near July 24.

"What I fear is that by late July, we're going to have to assume that there'll be so much virus in the community that somebody affiliated with the ball team -- whether it be a player, a coach, somebody -- who's going to unknowingly be infected and then run the risk of infecting everyone else," Persse said.

"I think this is an opportunity for major league sports of all denominations, if you will, to show they are really about the community. This is where we need to keep putting public safety and public health above any appearance that is about profit."

The comments came a day after Astros owner Jim Crane told reporters that he wanted to get not only players but also fans back into Minute Maid Park this summer and "sell some tickets, some merchandise, some cold beer. Whatever they'd like to have." Crane Kenney, the president of business operations for the Chicago Cubs, said this week that the team hopes to bring "some portion of our fan base back to Wrigley Field." Unlike Houston, Chicago has seen the virus steadily decline for more than six weeks.

In a statement to ESPN on Friday, Crane said the Astros "will not open our ballpark to fans if it is not safe."

"We would love to host fans at some point; however, we will only do that with city, county and state approval," he said.

MLB sources told ESPN that any decisions on admitting fans to games would be made by the commissioner's office, in conjunction with local officials.

Some public health experts interviewed by ESPN worry that even games without fans in attendance could increase opportunities to spread the virus, despite MLB's protocols.

"The thing that worries me ... is not actually the sporting event itself, but what happens around the sporting event, especially in states that have not instituted social distancing requirements," said Tara Kirk Sell, a senior scholar at the Johns Hopkins Center for Health Security.

"If you have an event like a baseball game and you have bars that are open, you're going to get congregation in bars in states that have increasing rates of disease. And so then you're going to see people in these bars who are sick, who give it to other people. Those are superspreading opportunities."

Dr. Carlos del Rio, a professor of global health and epidemiology at Emory University in Atlanta, said if it were up to him he wouldn't allow games in Houston. Based on the experience in New York, it will take months to control the epidemic, he said. "You don't want to disturb a city that is having an emergency," he said. "Houston has to control their epidemic before something like that happens."

Persse said Houston's best chance to avoid shutting down the season before it starts is for residents to play their part in reducing the virus' spread.

"I would say to sports fans, 'We can control this,'" he said. "Don't wait for the government or for anybody else; you are the one in control. Wear a mask, social distance. Get every single person you know to do the same.

"But if you dig your heels in and say, 'This is a bunch of malarkey,' I'm sorry, we're going to all go in the wrong direction, and major league sports is going to pay a price they don't have to pay."