Mets’ Syndergaard, a former 51, has hand-foot-and-mouth disease

NEW YORK — In the latest bizarre medical development for the baffling New York Mets, ace pitcher Noah Syndergaard is headed back to the disabled list after contracting hand-foot-and-mouth disease.

The team figures it’s likely Syndergaard caught the contagious virus when he made an appearance at a baseball camp for kids last Thursday during the All-Star break. Mets manager Mickey Callaway said that probably explains why Syndergaard weakened and his velocity decreased during Friday night’s victory at Yankee Stadium.

“Hand-foot-and-mouth, are you serious? I guess it’s very uncommon in adults, period,” Callaway said Sunday. “It’s kind of odd. Maybe the first DL stint in Major League Baseball with hand-foot-and-mouth? I don’t know. A record or something.”

According to WebMD.com, hand-foot-and-mouth disease is an infectious disease that “most often occurs in children under 10 and is characterized by a rash of small blister-like sores on the palms of the hands, soles of the feet, and in the mouth. Symptoms include fever, sore throat, and headache.”

The disease can spread from one person to another through saliva or fluid from blisters, among other things, and the infection normally passes in a week. The only treatment is a pain reliever such as acetaminophen, according to the website.

“It took its toll the other night. He had trouble breathing, and that’s why you saw his velo down,” Callaway said. “During the game, we couldn’t quite figure it out. But I put my hands on his legs to talk to him when he came out, and I felt his legs shaking. He was just weak and run down.”

Syndergaard, who pitched for the Las Vegas 51s in 2014 and 2015, missed most of last season with a torn lat muscle. He just returned from the disabled list July 13 after being sidelined for more than six weeks with a strained ligament in his right index finger. He is 6-1 with a 2.89 ERA in 13 starts this year for the struggling Mets, who began the night last in the NL East.

Assistant general manager John Ricco said the pitcher will be placed on the 10-day DL again Monday. Syndergaard stayed home Sunday and Callaway said no other members of the team have shown symptoms of the disease.

“It’s not a long-term thing and hopefully he misses one start,” Ricco said.

New York initially planned to recall rookie right-hander Corey Oswalt from Triple-A Las Vegas to pitch in Syndergaard’s place Wednesday against his hometown San Diego Padres. But after Sunday night’s scheduled game against the Yankees was postponed by rain, the Mets listed their starters for Tuesday and Wednesday as TBA.

The game against the crosstown rival Yankees will be made up in the Bronx on Aug. 13.

Cespedes may need surgery

The news regarding Syndergaard came two days after an alarming health revelation from slugger Yoenis Cespedes, who said he might need surgery on both heels that would require an eight-to-10-month recovery.

The 32-year-old Cespedes homered Friday night in his return from the DL after missing two months with a strained right hip flexor. He disclosed after the game that calcification on his heels has bothered him for 15 years and caused the lower-body injuries that have limited him to 119 games in 1½ seasons since he signed a $110 million, four-year contract.

“They’re all connected,” Ricco said. “So you’ve got to treat the whole problem. We got him to where the legs are strong, but the heel’s an issue. If he can manage the pain, he can play.

“Surgery hasn’t been a consideration up until this point, until he really brought it up the other night.”

Sewald recalled from Las Vegas

In other news, the Mets recalled reliever Paul Sewald, a Bishop Gorman grad, from Las Vegas. He fills the roster spot that opened when closer Jeurys Familia was traded to Oakland on Saturday.