Swine Flu Facts, Swine Flu Myths

Wearing face masks to ward off swine flu, worshipers gaze up at Our Lady of Guadalupe's in Mexico City's Basilica de Guadalupe on Sunday, April 26, 2009.

The Catholic church, Mexico's biggest, was shut down and Masses were canceled to prevent large gatherings, which encourage swine flu transmission.

The deadly, contagious new swine flu strain that sprang into being in Mexico and began setting off fears of a pandemic this past weekend has raised a lot of questions. To answer a few of the biggest, National Geographic News turned to the experts.

Q: How safe is eating pork?

A: As safe as it ever was.

Handling and consuming animal products, such as pork, can transmit some viruses. But that's not how the H1N1 swine flu virus is spreading, said Christine Layton, a public health policy analyst with the North Carolina-based nonprofit research institute RTI International.

Swine flu is a respiratory virus, spread from person to person. In other words: A sneezing chef is a threat, not the spare ribs he's basting.

In fact, if the swine flu virus were primarily being transmitted from pigs to people, public health officials probably wouldn't be so concerned. That kind of transmission tends to limit a virus's human spread to farmers and meat workers—people who are likely to come into contact with animals' bodily fluids.

(Related: swine flu pictures.)

Q. Can those face masks really protect me from swine flu?

A. Yes and no.

The blue surgical masks you've seen being passed out to Mexican pedestrians are better than nothing but probably only marginally useful, said Andrew Pekosz, associate professor of microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland.

While such masks block the relatively large, virus-carrying droplets sneezed out by infected people, the viruses themselves are much smaller and could easily pass through. Specialty masks, designated N-95 or N-99, are better filters but still not perfect.

For better protection, Pekosz recommends combining a mask with regular hand washing and keeping 3 to 4 feet (90 to 120 centimeters) away from other people.

Q. Is this just another media health scare? How worried should we be?

A. The truth lies somewhere in between panic and eye-rolling.

Making the jump from animal-to-person to person-to-person transmission is a rare skill for a flu virus to "learn." This ability makes H1N1 swine flu potentially dangerous—and makes the concern about it a bit different from the worries over bird flu, which has yet to make such a transition.

Human-to-human transmission is a big part of why public health officials are pouring resources into swine flu and why they want you to be aware that the virus is out there.

That said, experts like Johns Hopkins's Pekosz and RTI's Layton say there's currently no reason to lock yourself up in the house.

For one thing, the cases outside Mexico have been no more serious than your average flu bug. Right now, nobody is sure why that is. And while the severity of the symptoms could increase, Pekosz said there's not really an immediate, serious threat to individuals within the United States.

"However," he said, "it certainly merits the public paying attention, and it warrants the public health efforts that have been going on in terms of monitoring and research."

Q. How does a pig-bird-human mash-up swine flu virus happen, anyway?

A. Blame the pigs, and the virus.

Flu viruses are "very messy reproducers," RTI's Layton said.

All eight flu genes replicate independently. If a cell is infected with three different flu viruses, reproduction can mean a reshuffling of genetic material from multiple parents, thrown together randomly into the "baby" flu virus.

Most of the time, those cut-and-paste viruses don't work out very well, Johns Hopkins's Pekosz said. But every so often, this natural reassortment will come up with a new flu virus that has some kind of advantage over its competitors.

H1N1 swine flu is one of those, but we've certainly seen others in the past 30 years, he said. Pigs are part of the problem because they can become infected with flu viruses from birds and humans. As such, swine seem to provide a particularly good environment for this genetic square dance to take place.