# 4392
While the pandemic of 2009 certainly appears to have been less severe than the 1957 Asian flu, its true impact has not been determined.
It may take months, or perhaps years, before we have a really good handle on the severity of this virus.
Despite attempts by some to paint this virus as `no worse than seasonal flu’, we continue to see evidence that novel H1N1 differed from seasonal flu in terms of severity and the profile of patients hardest hit.
In a normal flu season, it is those over the age of 65 who make up 90% of the flu-related fatalities. During the past 10 months, those under 65 have borne the brunt of this virus.
While the vast majority of those infected by this virus only suffered mild to moderate illness, a significant number number of people suffered serious complications. In many cases, those victims developed severe, life threatening pneumonias.
Over the past eight months we’ve seen a steady parade of reports showing that there is something fundamentally different about the way the novel H1N1 virus attacks humans.
A few blogs on that subject include:
Canada: H1N1 Sent More To ICU Than Seasonal Flu
I Only Have Eyes For Flu
Cytokine Storm Warnings
NIH: Post Mortem Studies Of H1N1
Pathology Of Fatal H1N1 Lung Infections
Today we’ve another study, this time out of the Department of Virology, Erasmus Medical Centre and ViroClinics Biosciences BV, Rotterdam, The Netherlands which uses a ferret model to test the pathogenicity of the novel H1N1 virus against seasonal and bird flu.
Ferrets are often used in influenza studies due to their high susceptibility to the virus.
The entire study is a pay-per-view in the latest edition of The Journal of Infectious Diseases, so I only have access to the abstract.
If this study sounds familiar, there’s a reason.
This appears to be a follow up to research widely reported last summer (see The ECDC On The Ferret Pathogenicity Study, and Ferreting Out The Severity Of A Flu Virus) on the pathogenesis of novel H1N1 in ferrets.
The upshot, once again, seems to indicate that the novel H1N1 virus produces more severe pneumonia (in ferrets) than seasonal flu, although less severe than what is seen from the H5N1 virus.
The abstract follows:
Severity of Pneumonia Due to New H1N1 Influenza Virus in Ferrets Is Intermediate between That Due to Seasonal H1N1 Virus and Highly Pathogenic Avian Influenza H5N1 Virus
Judith M. A. van den Brand,Koert J. Stittelaar, Geert van Amerongen,Guus F. Rimmelzwaan, James Simon, Emmie de Wit, Vincent Munster,Theo Bestebroer, Ron A. M. Fouchier, Thijs Kuiken, and Albert D. M. E. Osterhaus
Background.
The newly emerged influenza A(H1N1) virus (new H1N1 virus) is causing the first influenza pandemic of this century. Three influenza pandemics of the previous century caused variable mortality, which largely depended on the development of severe pneumonia. However, the ability of the new H1N1 virus to cause pneumonia is poorly understood.
Methods.
The new H1N1 virus was inoculated intratracheally into ferrets. Its ability to cause pneumonia was compared with that of seasonal influenza H1N1 virus and highly pathogenic avian influenza (HPAI) H5N1 virus by using clinical, virological, and pathological analyses.
Results.
Our results showed that the new H1N1 virus causes pneumonia in ferrets intermediate in severity between that caused by seasonal H1N1 virus and by HPAI H5N1 virus. The new H1N1 virus replicated well throughout the lower respiratory tract and more extensively than did both seasonal H1N1 virus (which replicated mainly in the bronchi) and HPAI H5N1 virus (which replicated mainly in the alveoli). High loads of new H1N1 virus in lung tissue were associated with diffuse alveolar damage and mortality.
Conclusions.
The new H1N1 virus may be intrinsically more pathogenic for humans than is seasonal H1N1 virus.
