Annamay Pierse was in the proverbial "athletes' bubble" before the 2010 Commonwealth Games in India.

She focused on the positive, and filtered out the negative. In a media interview, she told a reporter she had no concerns about travelling to New Delhi amid an outbreak of dengue fever, which was brought about by the city's heaviest monsoon rains in 15 years.

"People were asking me, 'Oh, are you worried?' and I was like 'Oh no, not at all, I think it will be great, I've always wanted to go to India,"' Pierse said. "And then I am the one athlete that happens to get bit by a mosquito and it finishes my career."

The former world record-holder in the breaststroke contracted dengue fever, an illness so debilitating she eventually retired from swimming.

Her husband and paddler Mark Oldershaw will compete in this summer's Olympics in Rio de Janeiro, and so Pierse is watching news out of Brazil with a wary eye. Among the major headlines with less than six months to go: major outbreaks of both the Zika virus and dengue fever.

Negative headlines leading up to a major Games are nothing new. Air pollution was a hot topic ahead of the 2008 Beijing Olympics and fears of terrorism made news leading up to the 2012 London Olympics and 2014 Winter Games in Sochi.

"You are in a bubble as an athlete, and especially now being on the other side of it, knowing that you're in this bubble and you think, 'Nothing can happen to me,' and then being that athlete that realizes, it can actually happen to you," Pierse said. "Something like terrorism, there's nothing you can do if something's going to happen. You rely on everybody, your mission staff, and your country to keep you safe.

'Totally up to you'

"When it's something like dengue or Zika, that's totally up to you. Nobody can keep you safe from that, it has to be you being vigilant in wearing the mosquito spray and not putting yourself in situations where it can happen."

Zika has been linked to birth defects, and has some high-profile athletes voicing their concern. American soccer goalie Hope Solo told Sports Illustrated that, as of right now, she wouldn't compete in Rio.

"I would never take the risk of having an unhealthy child," Solo said.

The Canadian Olympic Committee's chief medical officer Bob McCormack is keeping an eye on Zika's fast-moving developments, but told The Canadian Press recently that he considers Brazil's other mosquito-borne viruses — dengue and yellow fever, chickungunya and malaria — as serious a threat to Canada's athletes.

Pierse and their six-month-old daughter Josephine will travel with Oldershaw to Rio. Dengue fever is particularly worrisome for the 32-year-old Pierse, because contracting dengue a second time is more likely to lead to dengue hemorrhagic fever or dengue shock syndrome, which is associated with a high mortality rate.

"I am [concerned], and it's kind of one of those things you watch," Pierse said. "I've thought about it, but not too much because I think you can scare yourself."

Pierse had been back in Vancouver for about a week after the Commonwealth Games when she woke up in "the most pain I've ever been in. It was just ridiculous. I had this crazy fever and everything hurt, absolutely everything."

It's sometimes called "breakbone fever," because of the pain.

"You feel like you've been hit by a bus," Pierse said from Melbourne, Fla., where Oldershaw was training. "My coach was calling me and saying, 'Why aren't you at the pool, you need to get to practice.' I said, 'Joe [Nagy], I cannot swim. I don't know what's wrong, but I can't swim.'

"It was seriously outrageous, the pain. I thought I was going to die. I actually woke up one morning and didn't think I was going to make it."

A tropical disease specialist eventually confirmed it was dengue fever.

Pain, then depression

Pierse said it was three months before she woke up without any pain, but then was hit with a bout of depression — another characteristic of the disease.

"A year and a half out from the Olympics, you really can't be sick," said Pierse, who didn't qualify for the London Olympic team and then retired.

Rio organizers have said they will inspect venues regularly for standing water where mosquitoes breed, until the Games open Aug. 5.

There were more than 67,000 registered cases of dengue fever in Rio de Janeiro state in 2015, and approximately 1.5 million Brazilians contracted the disease.

Olympic swimming champion Mark Tewksbury, who was Canada's chef de mission in London, said it's up to the team's mission staff to care for the athletes and help keep their mind off issues like the Zika virus.

"If we do our job right the team is almost unaware of it in a way. [The athletes] will hear the news stories, but they don't connect it to themselves and their experience," Tewksbury said. "If you're a woman, if you're pregnant, all that stuff is high alert, but for the most part, when you get there — I know it's a mosquito — but you're just kind of in this strange United Nations zone where you're just there to do your job and be focused on that."

The Government of Canada has posted a travel health notice for the Zika virus in the Americas, recommending pregnant women and those considering becoming pregnant discuss travel plans to those areas with their doctor.