The former NFL quarterback, Chris Chandler, explains how it is.

<p class = "canvas-atom-canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "When & nbsp;Sam Darnold& nbsp; curls up, presumably in his North Jersey apartment, and turns on his television to watch his & nbsp;New York Jets& nbsp;take the field without him& nbsp; Monday night, he will join an exclusive club. "data-reactid =" 15 "> When Sam Darnold curls up, presumably in his North Jersey apartment, and turns on his television to watch his New York Jets take the field without him Monday night, he will join an exclusive club.

A sore club, physically undermined and feverish. A miserable club whose number of members is estimated at two.

"This," says Chris Chandler, the only other NFL debut member known to have been ruled out by mononucleosis, "is a legitimate and hardcore disease."

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "Darnold was diagnosed with& nbsp; Wednesday and immediately quarantined in his apartment. According to Jets head coach Adam Gase, he had already lost five pounds. He missed training on Wednesday with what & nbsp;Gas originally called streptococcal. "data-reactid =" 18 "> Darnold was diagnosed on Wednesday and immediately quarantined in his apartment, according to Jets head coach Adam Gase, who had already lost five pounds and missed training on Wednesday. Gas originally called streptococcal.

But this – mono, as it is commonly called – is worse. Much worse.

Just ask Chandler, who spoke to Yahoo Sports Thursday from his home in Utah. He contracted the virus in the middle of a 17-year career in the NFL at the end of the 1995 season.

After a win of 42 to 33 of the Houston Oilers on the Denver Broncos, in which he had amassed 280 yards and three touchdowns, "I did not feel really good," he recalls.

Then came the sore throat. Tiredness. Weakness The following week, the Oilers traveled to Pittsburgh. "I did not get warm at all," recalls Chandler. "I actually started a touchdown pass in the first [half]. And then I went back to the locker room and fell asleep.

"I'll never forget to leave Pittsburgh," he said. "I literally went back to the cloakroom, on a concrete floor, lying on my back with a towel behind my head, and I fell asleep until the end of the match."

Chandler tried to return there the following week, returning home against Detroit. "I probably should not have played," he admits now. It lasted until halftime, but was replaced by rookie Steve McNair. Two or three weeks later, he has "nothing". His season, at the 15th week, was over.

Chandler still does not know how he became mono. "I'm not even sure what exactly is mono," he says. "But it's really a difficult thing to handle."

What is the mono? And why can not NFL players play with it?

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "MonoIn short, the virus transmitted by saliva can cause fatigue, fever, swelling and other unsavory symptoms that usually make life harder. "data-reactid =" 27 "> The Mono virus, in short, is a saliva-transmitted virus that can cause fatigue, fever, swelling and other unsavory symptoms that usually make life sad.

<p class = "canvas-atom web-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "Another potential symptom is an enlarged spleen. That's why Football players can not just fight in mono to win the game.The increase in the size of the spleen exposes it to a risk of breakage – and thus exposes players to a risk of serious injury, & nbsp;or even death. "data-reactid =" 28 "> Another potential symptom is enlargement of the spleen.This is why football players can not just fight in mono to win the pitch. enlargement of the spleen may cause it to rupture – and thus the players, at the risk of serious injury or even death.

Very few NFLs have been publicly diagnosed with it. Some, however, understand the fate of Darnold. Former 49ers offensive lineman Jonathan Martin missed the OMP with illness in 2014. Former retired defenseman Chris Long has learned he lost 20 pounds.

<p class = "canvas-atom-canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "" MISERABLE, "Long & nbsp;wrote on Twitter& nbsp; Thursday. "Can not breathe." "Data-reactid =" 30 ">" MISERABLE ", Long wrote on Twitter Thursday. "I could not breathe."

Other university football players diagnosed with the mono have had similar experiences.

When Michigan State cornerback Darian Hicks fell ill a few weeks before the opening game of his junior season, he first thought he had a sore throat. It was only after waking up one morning with his swollen and swollen tonsils that he realized that it was worse.

"It's a bit of a surreal feeling because you hear about mono but you never think you'll get it," Hicks told Yahoo Sports.

Over the next two weeks, Hicks remembers feeling constantly moody. He lost 12 pounds because he could not eat anything or drink without shaking his body.

Once Hicks was finally allowed to play after the end of the fall camp, he struggled to regain the muscle he had lost. Still, he persevered, returning to his starting position in mid-season, producing a record 33 career tackles and helping Michigan State qualify for Playoff College 2015.

"I did not let that prevent me from making an impact," says Hicks. "It forced me to do something new, it was a blessing in a curse."

Nevertheless, mono is both a draining condition and a rare condition. Darnold's is only the second known case among the beginner QBs of the NFL.

The story continues