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.
Then again, doctors said it's obvious that Dattolo is very dedicated to his students, and he may fight through an acute infection while still in school now and again.
"Most people suffer from two respiratory viral infections per year," said Dr. Christopher Ohl, an infectious disease expert at Wake Forest University School of Medicine. "Some of that [attendance] can also come from underlying constitution and personality. Just like how much people are more tolerant to pain, some people feel symptoms larger than others."
For some people, Ohl said symptoms can be disabling but others have a much easier time handling them.
Dr. Susan Rehm, vice chair of the department of infectious disease at Cleveland Clinic, said that cold and flu are often lumped into the same category, but it's important to understand the distinction between the two.
"There are times when we have a fever and muscle aches which make it impossible to go to work," said Rehm. "But the majority of the time, it's a gray zone. We don't feel well but maybe not sick enough to stay home, so how do we make that determination?"
The flu, often used to describe gastrointestinal problems or cold symptoms, is actually a respiratory virus. It has a much more abrupt and severe start than a cold. Usually, head and muscle aches come on quickly with the flu, and a fever and cough follow soon after. A cold has a gradual onset, characterized by a stuffy nose and a scratchy throat.
To prevent the flu, doctors say to get a flu shot, wash your hands regularly, and be mindful by using tissues and covering your mouth when coughing and sneezing. While they seem like simple remedies, such precautions can greatly reduce the spread of illness.
Doctors recommend keeping a social distance and avoiding crowds to reduce the spread of influenza.
"If you have any type of respiratory illness with a fever, you should stay home because influenza is pretty contagious," said Dr. Ohl. "But if we stayed at home every time we had the sniffles, there wouldn't be a lot of work productivity."
And school-aged children are some of the most important to watch, since they can give and get the flu quickly and easily.
"Children are nothing more than Petri plates we send to school and spread germs," said Ohl. "If everyone stays home when sick, we can reduce transmission."
The Centers for Disease Control and Prevention recommend that people stay home and avoid contact with other people except to get medical care. Most people do not need antiviral drugs.
But young children, people 65 or older, those with asthma and diabetes, and women who are pregnant are at higher risk of influenza complications and should talk to their doctor to see if they need further help. People who do visit the doctor should wear a face mask to avoid spreading the flu.
On average, children tend to be infected for five to seven days while adults are infected for about three to five days, depending on their experience and whether they've been vaccinated.
The CDC says that a person with the flu should stay home for at least 24 hours after the fever has gone away on its own without the help of an analgesic.
But, even though a classroom can be a breeding ground for germs, Dattolo says infections and coughs and fevers are not things to worry about.
"Sometimes people tell me, 'take a day off once in a while, you'll feel great,'" said Dattolo. Yes, teaching can definitely wear on you, but I take life day by day."
"I love teaching and as long as I love it, I'm going to keep on doing it," he said. "That's my medicine, so to speak."