A man dressed as Santa Claus receives his flu vaccine during a dress rehearsal before his weekend performance in Budapest, Hungary, Dec. 3, 2009. Christmas may come just once a year, but it's also the time when flu, colds and nasty intestinal viruses flourish — and it won't be joy they're spreading. THE CANADIAN PRESS/AP, Bela Szandelszky

TORONTO - Ah, it's the festive season, and that means get-togethers with family and friends — shaking hands, exchanging hugs and kisses, preparing and sharing meals. In other words, as the kids sing in the animated holiday Charlie Brown special: "Christmas time is here. We’ll be drawing near."

Hold on, though. Christmas may come just once a year, but it's also the time when flu, colds and nasty intestinal viruses flourish — and it won't be joy they're spreading.

So what to do if you come down with a Yuletide bug and you've been invited to parties or to join your extended family for Christmas dinner — or worse, plan to host it yourself?

"Honestly, if you're sick you shouldn't be there," says Dr. Michael Gardam, director of infection prevention and control at the University Health Network in Toronto.

"Infection control is not hard. It's basically, if you're sick, stay home."

For one thing, the holiday season is a time when people are "absolutely" more prone to getting sick, Gardam says. That may be because they're immunologically run down from the stress of preparing for the big day, from doing too much and getting inadequate sleep.

As well, the viruses that cause such maladies as influenza and colds are much more common during the winter months and seem to persist longer.

In part, that's because people tend to congregate indoors, where lack of humidity from central heating provides an environment in which microbes thrive and human hosts are ripe for a chain reaction of infection.

"Organisms that have an air-borne transmission component to them, when you're outside they don't spread easily because there's so much air," says Gardam. "But when you're indoors, they can be recirculated."

Surfaces can also provide a handy mode of transmission when people who are sick sneeze or cough into their hand or touch their mouth or nose, then come in contact with another person or handle an object. The roughly 100 different microbes that cause the common cold — including rhinoviruses and coronaviruses — can leave their infectious signature on doorknobs and countertops. And it's believed flu strains also often get spread that way.

That's why infectious disease specialists continually preach about frequent and thorough hand-washing, whether someone is down with a bug or not.

Determining when a person is no longer contagious and can safely socialize depends on the particular pathogen, says Gardam. "The average answer is once your symptoms have pretty much cleared up, you should be good to go."

"For things like influenza, you can be contagious for several days after the onset of symptoms," he said. But that's not the case with noroviruses, which cause a relatively short-lived but debilitating disease marked by explosive vomiting and diarrhea.

"It's insanely contagious and you don't develop immunity to it," says Gardam of norovirus, which is transmitted person-to-person and through contaminated foods and liquids.

He relates the story from several years ago of a post-surgical patient who had family visit, and one relative spent the time vomiting in the bathroom. It turned out the cause was norovirus. "Two days later, the whole ward was shut down."

Last summer, an outbreak at a Victoria seniors' home sickened more than 150 residents and staff, and was linked to nine deaths.

And norovirus can be an unwanted gift you keep on giving, he suggests: "Although your symptoms might clear up, you actually still have live viral particles in your stool for weeks after. You could be a walking disaster."

While anyone can catch a viral infection, very young children and seniors are most vulnerable to complications.

Respiratory synctial virus, or RSV, which causes flu-like symptoms in both children and adults, is particularly nasty in newborns and can develop into pneumonia, he said.

Estimates vary, but it's believed that about 2,000 Canadians, most at the opposite ends of the age spectrum, die each year from complications of influenza — which is why public health agencies repeatedly pound home the message about getting an annual flu shot.

So for those who end up with a holiday bug that leaves them sneezing and coughing, it might be an idea to rethink that visit to a grandparent in long-term care or having an elderly uncle for Christmas dinner, says Gardam.

"This comes up all the time. And I'm a fairly blunt individual, so I say, 'Do you want to kill Grandma? Is that where you're going?'"

He says people have to wrap their heads around the idea that what may be a simple cold to them could be deadly to someone else.

"So if grandma is a young healthy grandma, I'm not so worried. But if grandma is in a nursing home and is on oxygen and you're going into visit and you've got a cold, your cold could be influenza, it could be RSV, it could be any number of things which could actually cause a pneumonia and potentially kill them."

"And people really don't seem to pay attention to the fact that they're dragging the kids along who are hacking up a lung, and that illness is going to infect everybody else in the nursing home."

Candace Chartier, CEO of the Ontario Long Term Care Association, stresses that when it comes to a holiday get-together, it's better to be safe than sorry.

"If I could give any advice, I would say as much as the emotional impact of not taking your loved one home (can be upsetting), if you're sick it could save your resident's life," says Chartier, whose organization represents more than 400 private and not-for-profit facilities in the province.

"If you feel that you do want to take them home, there's measures you can take that would hopefully prevent it. But I would say it's not a good idea to bring a frail elderly person into an environment where there is a high degree of risk of an infection if you could possibly prevent it."

Gardam says that if someone with an infectious bug "absolutely" has to go to a holiday gathering, precautions should be taken to avoid passing the illness to others.

"Stay away from people, don't shake their hands, don't kiss them, wear a mask, wash your hands."

Chartier recalls one incident in which a woman came to visit her mother, and it wasn't until the nurse came into the resident's room later that evening that she discovered the daughter was visibly sick with a respiratory ailment.

The visitor was asked to don a gown, gloves and mask, but by that time it was too late — she had helped feed her mother in the dining room and been in close contact with other residents.

"Within four days, we had an outbreak on that side of the floor of influenza A."

While a family member who's been hit by a bug may feel guilty about not visiting or coming to pick up their loved one for holiday festivities, Chartier says there are alternatives that still allow togetherness. For instance, a sibling could be asked to have their parent for Christmas.

There's also the option of postponing the family celebration for another day, when everyone is healthy.

And technology means people can exchange their Merry Christmas wishes without passing along their germs, she says.

"There's Skype, there's email, there's phone, there's teleconferencing ... there are different avenues where you could technically be able to talk to your mom, short of reaching out and actually giving her that hug."

"There's a lot of ways that you could still share that emotional bond, but not put somebody at risk."

News from © The Canadian Press, 2013