The starting quarterback has mononucleosis and the star running back is having an MRI exam on his shoulder. Welcome to the world of New York Jets Coach Adam Gase, who had to step up to the microphones Thursday morning and announce that a player would miss at least one game with an illness guaranteed to draw the mockery of the New York tabloids.

“14,” he said with a pause, not naming the player, “has mono and will be out for this game.”

That’s right. No. 14 — a.k.a. Sam Darnold, the team’s second-year quarterback — will not play Monday night against the Cleveland Browns, and he might miss more than one game, too. Gase seemed to anticipate the tabloid reaction as he continued, with his cap pulled low over his eyes, “so Trevor [Siemian] will be starting and Luke Falk will be activated at some point and will be the backup.”

One former player pointed out that mono is no laughing matter, especially in a contact sport like football.

“Had it college freshman year,” former Philadelphia Eagles defensive end Chris Long tweeted. “MISERABLE. Woke up and my uvula was the size of a thumb. Couldn’t breathe. Was getting crushed on the message boards (the 2004 version of Twitter). Lost 20 lbs. And to top it all off … ya can’t party.”

The Jets and Gase knew something was up because Darnold, 22, was ill and wasn’t getting better. He had lost about five pounds over the past few days. “I looked at John [Mellody, the head athletic trainer] and said, ‘It’s mono, isn’t it?' Because they told me they were running all these tests and they thought it was weird that he wasn’t — that the antibiotics weren’t working as quick as they thought,” Gase said. “… My gut just [told] me that’s what it is.”

Mono is also known as “the kissing disease,” and the Mayo Clinic website notes the virus “that causes mono is transmitted through saliva, so you can get it through kissing, but you can also be exposed through a cough or sneeze, or by sharing a glass or food utensils with someone who has mono. However, mononucleosis isn’t as contagious as some infections, such as the common cold.”

It’s most common among adolescents and young adults, and complications include an enlarged or even ruptured spleen. Rest and fluids are usually prescribed.

Adding to the team’s problems — and it’s only Week 2 — was the news that running back Le’Veon Bell was getting an MRI on his shoulder, although the Jets think he merely has soreness. Bell joined the team in March after signing a four-year, $52.5 million deal; he ran for 60 yards on 17 carries in New York’s season-opening loss to the Buffalo Bills and gained 32 more yards on six catches.

(ESPN reported later Thursday that the MRI “revealed no major damage or tears.”)

Linebacker C.J. Mosley (groin) and defensive linemen Quinnen Williams (ankle) and John-Franklin Myers (foot) all missed practice for the Jets, while wide receiver Demaryius Thomas, obtained in a trade with the New England Patriots, won’t practice until Saturday.

There’s a chance Darnold will miss the following week, too, when the Jets play the Patriots in an important AFC East game. After that, the Jets, who lost, 17-16, to Buffalo in their opener, are blessed with a bye.

“I don’t want to put predictions on anything,” Gase said. “I’m just glad we’ve got the bye week when we do.”

After the bye, the Jets play the Eagles, Dallas Cowboys and then the Patriots again, part of a run of four straight games against 2018 playoff teams.

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