Winnipeg Free Press - ONLINE EDITION

Why is virus killing only Mexicans?

Experts say flu's mutation, genetics could be factors

  • Print

OTTAWA -- As they continue to analyze the new swine-flu virus, researchers are grappling with a puzzling question: Why are the Can­adian and U.S. cases milder than those in Mexico?

It's not just an interesting question for scientists to ponder. Over the com­ing days and weeks, public-health of­ficials will be watching like hawks to see if the milder cases are a sign the outbreak is dissipating, or whether such cases are just the prelude to a full­blown pandemic.

Infectious-disease experts note the Spanish flu pandemic started out mildly in the spring of 1918 before re­emerging with a vengeance in the fall.

"We cannot be complacent, because this particular influenza strain, just like any other virus or flu strain, can still continue to mutate and it can mutate in either direction," said Dr. Colin Lee, as­sociate medical officer of health at the Simcoe Muskoka District Health Unit.

There have been more than 150 sus­pected deaths in Mexico.

On Wednesday, the United States an­nounced a toddler from Mexico City had died after catching the swine flu.

To date, most of the cases in countries other than Mexico have been relatively mild. Several theories are emerging to explain the discrepancy.

One is purely statistical.

In any flu outbreak, there will be a large number of mild cases and a much smaller number of severe, or even fa­tal, cases. Given that Mexico is the epi­centre of the outbreak, it makes some sense more deaths would have been confirmed there so far, noted Dr. Ger­ald Evans, chief of the infectious-dis­eases division at Queen's University.

Experts also say the virus could have mutated, becoming milder as it mi­grates to other parts of the world.

It's also possible the strain found in places such as Canada and the U.S. is at an earlier stage of mutation than the original strain in Mexico, which would suggest Canada and the U.S. are in store for much more serious cases.

"The question really is are we look­ing at the earlier stage of the disease, which means the strain we are seeing now (in Canada and the U.S.) is just an earlier version of the Mexican strain," said Bhagirath Singh, scientific direc­tor of the CIHR Institute of Infection and Immunity at the University of Western Ontario.

There is also the possibility some­thing in the genetic makeup of Mexi­cans is making them more susceptible, although some experts dismiss the hy­pothesis.

"We do not differ genetically that much from our Mexican brothers and sisters as some people might speculate, and genes very rarely have anything to do with the expression of infectious dis­eases," said Evans. Some point to poor health care in­frastructure in some parts of Mexico, which would make it more difficult for some Mexicans to receive care, or even air pollution in Mexico City.

"This is a respiratory disease, and in parts of Mexico, especially Mexico City, there's a lot of pollution, and it may exacerbate respiratory infec­tions," said Lee. It will likely be weeks before re­searchers have a solid hypothesis.

"The Mexican data may not be very reliable because of their testing and healthcare infrastructure, so they may not be seeing the milder cases," Lee. "It's so early right now that nobody has really confirmed the data."

-- Canwest News Service

Fact Check

Fact Check

Have you found an error, or know of something we’ve missed in one of our stories?
Please use the form below and let us know.

* Required
  • Please post the headline of the story or the title of the video with the error.

  • Please post exactly what was wrong with the story.

  • Please indicate your source for the correct information.

  • Yes

    No

  • This will only be used to contact you if we have a question about your submission, it will not be used to identify you or be published.

  • Cancel

Having problems with the form?

Contact Us Directly
  • Print

You can comment on most stories on winnipegfreepress.com. You can also agree or disagree with other comments. All you need to do is be a Winnipeg Free Press print or e-edition subscriber to join the conversation and give your feedback.

You can comment on most stories on winnipegfreepress.com. You can also agree or disagree with other comments. All you need to do is be a Winnipeg Free Press print or e-edition subscriber to join the conversation and give your feedback.

Have Your Say

New to commenting? Check out our Frequently Asked Questions.

Have Your Say

Comments are open to Winnipeg Free Press print or e-edition subscribers only. why?

Have Your Say

Comments are open to Winnipeg Free Press Subscribers only. why?

The Winnipeg Free Press does not necessarily endorse any of the views posted. By submitting your comment, you agree to our Terms and Conditions. These terms were revised effective April 16, 2010.

letters

Make text: Larger | Smaller

LATEST VIDEO

Fire destroys one St. Norbert home, damages another

View more like this

Photo Store Gallery

  • June 24, 2012 - 120624  -  Amusement riders on the last day of The Ex Sunday June 24, 2012.    John Woods / Winnipeg Free Press
  • A gaggle of Canada geese goslings at Woodsworth Park in Winnipeg Monday- See Project Honk Day 05- May 07, 2012   (JOE BRYKSA / WINNIPEG FREE PRESS)

View More Gallery Photos

Poll

Should Canada send heavy military equipment to Ukraine?

View Results

View Related Story

Ads by Google