# 3695
Despite all of the assurances that the novel H1N1 virus is `similar in severity to seasonal flu’, there are obviously differences in the way the novel virus behaves.
We’ve heard a great deal about the `age-shift’ to younger victims – something we often see with pandemic viruses – but so far we’ve heard very little about the pathogenesis of the virus; how the disease progresses inside the body.
Today Helen Branswell of the Canadian Press brings us a fascinating interview with the CDC’s chief pathologist regarding post-mortem examinations of the lungs of H1N1 fatalities.
I’ll just get out of the way and let Ms. Branswell take it from here.
Lung damage in fatal swine flu cases more bird flu than seasonal flu: expert
By Helen Branswell Medical Reporter (CP)
TORONTO — The lungs of people who have died from swine flu look more like those of the victims of H5N1 avian influenza than those of people who succumb to regular flu, the chief of infectious diseases pathology at the U.S. Centers for Disease Control says.
Study of about 70 fatal H1N1 cases so far also reveals there may be more incidences of co-infections with bacteria than was earlier thought, Dr. Sherif Zaki told The Canadian Press in an interview.
The damage to lung tissue is consistent with that inflicted by ARDS or acute respiratory distress symptom, Zaki says, referring to an often-fatal, difficult-to-treat syndrome that can have a number of causes. The U.S. National Heart, Lung and Blood Institute estimates about 30 per cent of people who develop ARDS die.
"In terms of the disease, yes, it (H1N1) is remarkably different than seasonal flu," Zaki says. "The pathology looks very similar to H5(N1)."
Up until now we’ve heard little about bacterial co-infections in fatal H1N1 cases. Dr. Zaki makes the point that pneumococcal vaccines might be of value in younger people, to prevent some of these infections.
Although I don’t offer medical advice in this blog, I have suggested on many occasions that people should consult with their primary care provider about the advisability of taking the Pneumococcal polysaccharide vaccine (PPV) – even if you aren’t sure you fall into a recommended category.
A couple of blogs on the subject include:
Referral: Effect Measure On Pneumococcal Vaccines
CDC Issues Pneumococcal Vaccine Recommendations
Given the comparisons being made between the lung damage wrought by the novel H1N1 virus and H5N1 Bird flu, it might be an appropriate time to take another look at the PNAS paper entitled Early and sustained innate immune response defines pathology and death in nonhuman primates infected by highly pathogenic influenza virus by Carole Baskin et. al., which analyses the pathogenesis of the H5N1 virus compared to seasonal flu, and 1918-like viruses.
With much trepidation I wrote a 3-part-layman’s guide to this paper last January. It was an ambitious undertaking, but to my delight the study’s author Carole Baskin, read it and commented positively on it.
Dissecting the Influenza Pathogenesis Study Pt. 1
Dissecting the Influenza Pathogenesis Study Pt. 2
Dissecting the Influenza Pathogenesis Study Pt. 3
I’m not sure that we can assume that the same damage observed at the cellular level with H5N1 is occurring with H1N1, but upon gross examination the two appear to be producing similar pathologies.
In any event, these three essays are a good review of the immune system, and our defense against viruses – novel and otherwise.
