Will a new global pandemic be the lasting legacy of Qatar’s World Cup, which ended Sunday with one of the most exciting finals in the history of the soccer tournament?

Virologists doubt that the so-called camel flu could become as viral or deadly as its close relative, Covid-19, yet authorities are telling physicians to watch those returning from Qatar for symptoms such as fever, respiratory ailments, and lasting aches. 

Sound familiar? Conflicting messages from public officials and medical professionals made the rounds in late 2019, when a flu-like disease spread around the world faster than one of Elon Musk’s Twitter polls goes viral. Currently, the odds are low that Doha will become a new Wuhan, but caution must be exercised. 

Three French soccer players who suffered from what was described as “flu-like symptoms” were scratched from their team’s lineup in last week’s semi-final match against Morocco. This raised fears in some quarters that a virus causing a disease known as Middle East Respiratory Syndrome would spread in countries where it has previously been mostly absent.

Although Kingsley Coman, Dayot Upamecano, and Adrien Rabiot were back on the pitch for France in the final against Argentina, their team’s sluggish performance Sunday, at least early on, raised speculations about locker room spread of MERS, or camel flu. The French team never did specify what exactly ailed the three players. 

Meanwhile, as disappointed fans of Team England went home earlier, Britain’s Health Security Agency advised doctors to be on the lookout for patients suffering from fevers and breathing difficulties. “Clinicians and public health teams should specifically be alert to the possibility of MERS in returning travelers from the World Cup,” the advisory said. Australian authorities issued a similar cautionary warning. 

First identified 10 years ago in Saudi Arabia, MERS-CoV is a zoonotic virus mostly transmitted to humans from camels, as well as between humans. The disease thus far has not been nearly as prevalent as its closely related cousin, Covid-19. Only 2,600 camel flu cases in humans have been identified, with 1,000 deaths confirmed. Eighty percent of all cases have been confined to Saudi Arabia.

The origins of Covid-19 are widely contested, with several reports linking the outbreak to a lab at Wuhan, China. MERS, in contrast, is widely known to originate in camels. There is no vaccine to date, and while MERS is less contagious than Covid-19, it is also more deadly. 

MERS “is less transmissible in the community” than Covid-19, but “there is a higher mortality rate” among those who are infected, the dean of the national school of tropical medicine at Baylor College, Peter Jay Hotez, told the Sun.

With Covid-19, Dr. Hotez noted, there has been a “large number of asymptomatic individuals,” which meant that many people transmitted the disease to others without knowing they had it. “With MERS, if you have it, you’re pretty sick, so you aren’t hanging out in bars or going to sporting events.”

Dr. Hotez points out that there are two annual events, the Hajj and the Umrah, that bring Muslims to Mecca, Saudi Arabia, from around the world. There, millions of pilgrims gather in close proximity before returning to their homes. Yet, Dr. Hotez says, in past years transmission of MERS following the Hajj and Umrah has been relatively low.

Yet, there are several factors that add fears to the aftermath of the Qatar soccerfest .

The crowds that poured into the tiny country come from more corners of the world than the places where most Hajjis come from — the Mideast, Northern Africa, and South Asia. That is where to date most of the MERS cases were identified outside of Saudi Arabia. New cases in Europe and the Americas could alter the global equation. 

Also, Qatar, a very hot country, has introduced a new innovation in stadium architecture: advanced outdoor air conditioning. When the World Cup stadiums were being built, the hosts described to this reporter how the system works, evenly blowing cold air across the semi-domed arena, to the field and under the fans’ seats. Such a system may well spread viruses just like what happens in hospitals, bars, or other indoor spaces. 

To make matters even dicier, Qatar was so eager to put its desert culture on display for the global visitors that it organized a camel beauty pageant to coincide with the soccer tournament. While a camel named Nazaa’a “batted her eyelashes and flashed a toothy smile for the television cameras,” her fellow beasts may well have transmitted MERS to the adoring crowds.

“I’ve never been to a camel beauty contest,” Dr. Hotez said, “but it’s not ideal” for camel flu prevention. Yet, he added, the MERS virus’s incubation period is five to six days, so “if we don’t see any cases by the end of this week we should be okay.”