A Boy Scout from Connecticut who is believed to have caught bubonic plague while visiting Wyoming has fully recovered from the rare, potentially deadly illness.

The 18-year-old, whose name and hometown haven’t been released, recovered after a course of the antibiotic Cipro, according to a doctor who treated him at MidState Medical Center in Meriden.

The young man was among hundreds of Scouts who built trails and did other service work in northwest Wyoming in late July and early August before returning home to Connecticut.

He arrived at MidState Medical Center’s emergency room with a swollen gland and high fever, and was placed on antibiotics for a suspected case of the mumps until tests later determined he had bubonic plague.

“We did get the history of him being in Wyoming,” said Dr. Robert Levitz, an infectious diseases specialist. “I didn’t think it was plague, but the classic symptoms were there."

Bubonic plague causes fever, headache, and exhaustion and is spread by rodents, rabbits, and fleas.

Being on antibiotics for several days helped prevent the teen from developing pneumonic plague, which can spread through coughing and led to millions of deaths in the Middle Ages, Levitz said.

Doctors at Clinical Laboratory Partners in Newington pinpointed the disease-producing pathogen in the teen’s blood as Yesina pestis, or bubonic plague.

“I didn’t believe it,” said Dr. Jaber Aslanzadeh, director of microbiology at the lab. “I said, ‘Oh my God, this can’t be.’ I have been in business for 20 years, and this is the first time I had seen it.”

The laboratory does bioterrorism testing for the state health department and, following protocol, notified the department of the rare find.

“They didn’t believe us, actually,” Aslanzadeh said. “This is too unusual.”

The Centers for Disease Control and Prevention in Atlanta confirmed the finding.