SEATTLE -- A dangerous strain of staph infection, known widely as "the superbug" has killed a Seattle man.

King County Medical Examiner confirmed Thursday that John Jones, 46, died of methicillin-resistant Staphylococcus aureus, also known as MRSA.

The highly contagious strain of staph infection is resistant to antibiotics.

VIDEO: Deadly Virus Kills Seattle Man

Health officials say MRSA used to be contracted mostly by people visiting sick patients in the hospital.

Also on Thursday, Port Townsend High School closed its athletic facilities and canceled its final football game of the season after a member of its football team reported contracting the same staph infection.

In a letter sent home with students, Port Townsend High School Principal Carrie Ehrhardt and Assistant Principal Patrick Kane said they were unsure how the student contracted the infection.

"We are unable to determine how the student contracted the infection, and it is likely that we will never know," the letter said.

“I didn’t realize how serious it was until I got the letter home and showed my parents,” student Kelsie Sheezly said.

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According to the Washington State Department of Health, MRSA skin infections are serious and need to be treated. They are contagious and can be spread to other people through skin-to-skin contact.

"We do know that it is highly contagious and easily spread. The best way to maintain good health from this disease is to practice good hygiene on a regular basis," the letter said.

According to the letter, PTHS has been assured by state health authorities that it is safe to remain open.

The school’s gym is closed Friday and the district said they plan to have cleaning crews disinfect the school over the weekend.

Parents were told students would be excused from classes if they chose not to attend Friday.

Only one-quarter of the student body was in attendance Friday, KIRO 7 Eyewitness News reported.

“The classes were very empty. My largest class had 10 or 15 people in it. We didn’t do much. A lot of the test were canceled it was just kind of a weird feeling going on,” student Jenny Peterson said.

A KIRO 7 investigation last year exposed the spreading of the bacteria revealing that cases are up 50 percent to 60 percent in the last few years in gyms, among athletic teams and inside jails and nursing homes.

Doctors said one possible explanation for more cases is people's overuse of antibiotics.

They said washing hands thoroughly is the best way to protect yourself.