TORONTO -- Some COVID-19 patients say they experienced ‘extremely mild’ symptoms before testing positive for the novel coronavirus, raising concerns that the virus is being spread by some who don’t realize they’re infected.

For Dr. Miryam Carecchio, a neurologist in Padua, Italy, discovering she was infected, came as a shock.

“I had no fever, no cold, no sore throat, and I had no major issues,” she told CTV National News.

The assistant professor at the University of Padua did experience muscle pain in February, she said, so she took some Tylenol, called in sick, and was back to work the following day.

She later experienced changes, including a loss of taste in her mouth, but didn’t think the symptoms were extreme enough to be linked to the COVID-19 outbreak.

“I didn’t feel any of my very minor complaints were consistent with this infection,” she said.

The 37 year old says she was tested – “by chance” at the hospital -because she was not ill, had not travelled to a high risk area, and didn’t fit the criteria for testing. Last Thursday she got the news she was positive and had to be quarantined until March 20, her birthday.

“I was surprised,” she said. “I was a bit scared, I must say.”

More than 100 of her contacts were tested for infection, three of which tested positive. They are now all in isolation with what Dr. Carecchio says are mild symptoms.

On Monday, Canada recorded its first death as a result of the virus: that of an elderly man in a North Vancouver care home. As of March 9, there were another 67 confirmed cases in Canada across four provinces. Globally, there were over 113,600 confirmed cases. More than 4,000 people have died worldwide, making up a death rate of about three per cent. Despite the alarming numbers, around 63,600 are confirmed to have recovered.

For some, the most difficult part of the recovery was the isolation, not the symptoms. Carl Goldman, a 67-year-old who was on the Diamond Princess cruise ship, says he would have been back to work within 24 hours if it were another illness, based on his symptoms.

“Everyone I have spoken with -- and it has been many -- who have picked up the virus, they seem to have similar symptoms,” he said. “About equal to a very, very minor cold.”

Goldman, who owns KHTS radio in Santa Clarita and has been blogging about his quarantine journey on the station’s website, said he had no symptoms when he got on the plane home from the cruise. But after a two-hour nap during the flight, he woke up with a high fever of over 103 degrees. He was placed in a quarantine area on board and fell asleep again. By the time they landed, his fever was gone.

“What’s so weird about the symptoms of the coronavirus, COVID-19, is that unlike a normal cold or flu, I didn’t get a sore throat, never got any sniffles. No sneezing, no body aches, no headache. Usually with high fever, I would get chills or sweats or a combination of both. I had none of those.”

He did have a “dry cough” that stayed with him for more than two weeks. “Other than that I am fine,” he said. He’s been quarantined at the University of Nebraska Medical Center in Omaha, where he continues to be tested for the virus. His last results, given to him on a Post-It note from staff, were positive for the virus in his nasal passage.

“I am feeling great today,” he said. “I am doing my 10,000 steps in my rooms, pacing 14 steps until I hit a wall, so that is a lot of paces. I am writing. I’m talking to people. I have an exercise bicycle in here. Other than being stuck here inside a room, I am fine. I am 100 per cent healthy.”

While the lack of alarming symptoms may seem to be a comforting thought, it’s perhaps what makes the virus more unsettling, suggests Dr. Carecchio. “It’s not possible to recognize the viral infection at the very beginning. Sometimes it will never be possible to recognize it,” she said.

Many cases may be the caused by “pre-symptomatic transmission,” infection by someone without symptoms, according to a preliminary study posted medRxiv that modelled the outbreak in China. The research estimates that pre-symptomatic transmission caused 48 to 52 per cent of infections in Singapore and Tianjin. The study has not been peer-reviewed. Other research suggests that over 80 per cent of patients who have mild or no symptoms can be contagious , leading some health professionals to call for stricter protocols even for people not exhibiting symptoms.

“Focusing only on isolating sick people will miss many contagious people,” wrote Tom Inglesby, director of the Johns Hopkins SPH Center for Health Security, on Twitter Monday.

The lack of symptomology may explain why a growing number of Italian health care workers are infected. Dr. Carecchio says that more than a dozen health care workers in her facility have tested positive for COVID-19. One colleague is in ICU with respiratory distress.

“There is an increasing number of doctors who cannot work because they've got infection,” she said. “If you reduce the number of doctors and the medical staff in general, in this system, that is very, very worrying.”

That’s why, she said, human contact should be limited, even here in Canada where there are fewer than 70 confirmed cases.

“If you don’t touch people, shake hands, kiss people, if you don’t have physical contact, that is very important to reduce the likelihood of the virus spreading. Washing hands very frequently. Try to avoid crowded places unless it is strictly necessary,” she said.

It’s a warning repeated by Dr. Lisa Barrett, an infectious disease specialist in Halifax. “At this point, everyone should be acting as if there are respiratory viruses in their community and doing all the things they can on a daily basis to prevent the spread of viruses, particularly respiratory viruses.”

“I hope all Canadians will make the most of it. If you have time to prevent and start behaving in a certain way, that would be extremely effective,” said Dr. Carecchio. “This is the right time to prevent it. Everyone can start working on prevention right now, without waiting for the disaster to come.”