How Swine Flu Killed the Young and Healthy

indigo girl · Dec 5, 2010

How Swine Flu Killed the Healthy - ScienceNOW

The H1N1 pandemic virus that took the world by storm in 2009 may have had an unexpected accomplice. Some of the thousands who died may have been victims of their own immune systems, suggests a paper appearing in Nature Medicine today. The study provides a possible answer to one of the most baffling questions since the virus appeared in the spring of last year: Why did the virus cause most damage in 20- to 50-year-olds--who are generally the healthiest--while sparing the very young and the very old?
The reason, according to Polack, is that their immune systems' programming backfired. After looking at lung samples from 75 young and middle-aged adult victims of the 2009 pandemic, they found an uncanny amount of a protein called C4d, a molecule that normally binds to antibodies to form virus-fighting immune complexes.
When antibodies fight a virus under normal conditions, Polack says, they call in C4d, a compound that can destroy viruses. In the case of flu, most people had antibodies to seasonally circulating influenza strains, but these antibodies were a poor match to the pandemic virus. Although they recognized the virus and latched on to it, they weren't able to stop it from replicating, says Polack. When the antibodies and the C4d formed the immune complexes, Polack speculates that the system spiraled out of control. Instead of punching holes in the viruses, the immune complexes punched holes in the victims' veins and flooded their lungs with water and plasma. "The immune system gets fooled into activating this particular immune defense, and it causes harm," says Niranjan Bhat, an infectious disease physician at Johns Hopkins Children's Center in Baltimore, Maryland, who was not part of the research.

(hat tip flutrackers/tetano)

Swine flu rears its head again | Herald Sun

So why does this happen with some young people but not most like this formerly healthy young man in Australia who became sick just this past October 2010, and then unexpectedly died? Why him?

Christopher Patterson thought he had a persistent cold until he was diagnosed with swine flu and flown to Melbourne from his home at Inglewood, near Bendigo.
"He was just a normal, healthy kid," she said.
His death will officially be signed off as respiratory airways distress syndrome, a complication of swine flu.