Could Swine Flu Reemerge as a Pandemic?

Genetic mutations could lead to swine flu outbreak

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) What stands between a flu that mostly affects pigs and a deadly virus that can jump from human to human? According to a new study, the barrier is only a few genetic tweaks.

Since the swine flu outbreak of 2009, the virus has laid low, affecting only a few Americans who came into direct contact with pigs at local fairs.

But scientists have found that a flu strain circulating among pigs in Korea has the potential to become a pandemic.

"Get vaccinated for the upcoming flu season."

The study was a collaboration between Korean scientists and the Children’s Research Hospital in Memphis, Tennessee. It was published in the Proceedings of the National Academies of Science.

A pandemic is an occurrence of infectious disease that spreads across large swaths of human populations. Scientists are constantly on the alert to monitor flu strains, in the hopes of avoiding a devastating outbreak like the 1918 Spanish flu, which infected almost one-third of the world's population.

In 2009, the swine flu pandemic, also known as H1N1, killed 18,500 people.

There's now a vaccine for H1N1, but scientists fear that new strains could emerge that people are not immunized against.

In this study, scientists studied ferrets, who react to flu in much the same way as humans. They infected the ferrets with a strain of swine flu found in Korean pigs, which is genetically similar to strains found in North America.

One strain that they tested proved to be deadly in ferrets. Once the ferrets were infected, the virus made two mutations within their bodies and was able to infect other ferrets.

In other words, a genetic switch was turned on that allowed the virus to make the jump from pig to ferret, and then from ferret to ferret. All three of the ferrets died within ten days of becoming infected.

This is nothing to be alarmed about: The experiment was controlled in a lab, and may never show up in human populations.

Nancy Cox, a flu researcher at the Centers of Disease Control and Prevention told NPR's Shots blog that the strain tested in Korea does not match any of the strains that have jumped from pig to human. Only one person has died from the recent bout of swine flu in the US.

But the bottom line, according to the study authors, is that pigs are still very much capable of producing future pandemic viruses.

Worldwide flu surveillance is ongoing and scientists will be using the genetic markers discovered in this study to watch for potentially deadly strains of flu that may arise in the future.

The study was published in September 2012.

Reviewed by: 
Review Date: 
September 12, 2012
Last Updated:
October 5, 2012