Alphonse Dattolo, a language teacher at Glen Rock High School in New Jersey, says he has worked more than 7,000 days in a row without one single day off. For those trying to do the math, that's more than 40 school years without an absence from the daily school grind.
Dattolo, 62, says he has been sick here and there in the past 40 years, but nothing that warranted a missed day of school. His students keep him going, Dattolo said, and he has no plans to retire any time soon.
"Sure, there are days when I haven't felt great and wanted to stay in bed, but then I think of the students," said Dattolo. "If you're a good role model, you show by example. My students invigorate me. They're my adrenaline."
Some doctors say Dattolo was probably blessed with a great immune system, but it is unlikely that Dattolo has never had the flu or other contagious illness in the past four decades.
"He may not have perceived himself to be ill, but it's not possible that he hasn't had multiple infections with common gastrointestinal and respiratory problems in that long of time," said Dr. Susan Coffin, medical director of infection and prevention and control department at Children's Hospital of Philadelphia.
But Dr. Paul Glezen, professor of molecular virology, microbiology and pediatrics at Baylor College of Medicine, said that some bodies are better at fighting illness than others.
"Some people are just genetically programmed to have a better innate immunity, and they have a natural ability to respond to viruses," said Glezen. "[Dattolo] is in contact with students regularly, so he may be fortunate in that he can overcome those infections more rapidly and with fewer consequences than others."
Dr. Richard Besser, ABC News' chief health and medical editor, agreed that it is quite possible a person can avoid severe illness for most of their lifetime. Getting a flu shot, washing your hands, eating right, and getting plenty of rest can keep a person healthy and robust.
But "if [Dattolo] has come to work when he is sick, that would be concerning," said Besser. "A mild cold is no reason to stay home, but anything more than that, it's best to not get other people sick."
"Presenteeism" is a term often used by infectious disease experts to describe employees who are at work, but cannot perform to their best ability because they are sick, potentially spreading their germs to others. Both factors can lower the overall productivity of the workplace.
"People need to come into work with not just the training but also the health precautions necessary for the job, like immunizations and feeling well," said Coffin. "People show up to work thinking that their co-workers are better off if they're present, but the downside is that they're potentially infectious to others.
"It takes some strength to say, 'no, I'm not going to go to work today,'" Coffin said.
And on the flip side, Coffin said that those same people have to support their co-workers when they're ill as well.
Datollo said that he hasn't had a flu shot in decades. But still, doctors say Datollo's superb health could be in his DNA.
"There is probably a lot related to genetics in terms of one's susceptibility to infection exposure, [and] what viruses you are in contact with," said Besser.