Antibiotics crucial for pandemic21st August 2008
Most of the deaths in the great influenza pandemic of 1918-1919 were caused by bacterial pneumonia, not the H1N1 influenza virus itself, meaning that governments should be stockpiling antibiotics as well as antiviral medicines against the threat of the next pandemic, a new study has found.
Researchers from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, studied lung tissue of pandemic victims and historical data from the period, to find that most victims succumbed to bacterial pneumonia following influenza virus infection.
The pneumonia was caused when bacteria that normally inhabit the nose and throat invaded the lungs along a pathway created when the virus destroyed the cells that line the bronchial tubes and lungs, they concluded, warning that a future influenza pandemic may unfold in a similar manner.
The report, published in The Journal of Infectious Diseases, concludes that comprehensive pandemic preparations should include not only efforts to produce new or improved influenza vaccines and antiviral drugs but also provisions to stockpile antibiotics and bacterial vaccines as well.
"The weight of evidence we examined from both historical and modern analyses of the 1918 influenza pandemic favours a scenario in which viral damage followed by bacterial pneumonia led to the vast majority of deaths," co-author and NIAID Director Anthony Fauci said in a statement. "In essence, the virus landed the first blow while bacteria delivered the knockout punch."
Researchers examined lung tissue samples preserved in paraffin blocks from 58 soldiers who died of influenza at various US military bases in 1918 and 1919. They found that the tissue damage in the samples ranged from "changes characteristic of the primary viral pneumonia and evidence of tissue repair to evidence of severe, acute, secondary bacterial pneumonia".
NIAID co-author and pathologist Jeffery Taubenberger said this meant that the predominant disease at the time of death appeared to have been bacterial pneumonia, together with evidence that the virus destroyed the cells lining the bronchial tubes, including cells with protective hair-like projections, or cilia.
This effectively stripped the entire respiratory tract of its normal defences, rendering it vulnerable to attack even at the deepest level by bacteria that usually live in the nose and throat, which migrated down the newly created pathway.
Taubenberger and NIAID co-author David Morens combed scientific and medical journals published in English, French and German for autopsy reports conducted on influenza victims, tracking down 8,398 individual autopsies conducted in 15 countries.
Pathologists even at the time were nearly unanimous in the conviction that deaths were not caused directly by the then-unidentified influenza virus, but rather resulted from severe secondary pneumonia caused by various bacteria.
It is likely that the greater availability of antibiotics in the later pandemics of 1957 and 1968 contributed to the lower number of deaths from those outbreaks worldwide.
The authors warn governments to prepare for a similar pattern of viral damage followed by bacterial invasion in a future pandemic, which may be caused by the H5N1 strain of avian influenza, should the virus mutate to a form easily transmissible between humans.
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Title: Antibiotics crucial for pandemic
Author: Luisetta Mudie
Article Id: 7944
Date Added: 21st Aug 2008