# 3429
Determining the pathogenesis (progression of disease) with this novel H1N1 virus has been a high priority for doctors and scientists over the past couple of months.
While most people seem to recover from this virus without incident, it has produced unusual symptoms and severe illness in some victims. There have - as an example - been a higher-than-normal incidence of gastro-intestinal symptoms than we normally see with influenza.
And for some small percentage of victims, this virus has produced unusually severe and often life-threatening illness. Clearly, this virus isn’t `mild’ for everyone.
Today we get a report from Nature.com on a pair of studies using ferrets - which catch and transmit influenza much like humans – which gives us some of the first looks at the pathogenesis of the novel H1N1 virus.
I’ve just excerpted the opening paragraphs, follow the links to read it in its entirety.
Swine flu reaches into the lungs and gut
Published online 2 July 2009 | Nature | doi:10.1038/news.2009.617
Studies of ferrets reveal details of disease.
Katharine Sanderson
The swine flu virus was found in the lungs and intestines of infected ferrets.CDC
The swine flu virus can reach deep into the respiratory system and even as far as the intestines — findings which could explain why the disease's symptoms are different from those of seasonal flu.
Two separate groups have been using ferrets to investigate how harmful A(H1N1) influenza virus is and how easily it is transmitted. One of the studies was by Terrence Tumpey at the Centers for Disease Control and Prevention in Atlanta, Georgia, and his colleagues, and is published in Science1. Tumpey's team put droplets of three different swine flu viruses, and one 'seasonal' flu virus into the noses of ferrets. Some ferrets shared cages with other uninfected ferrets and some were placed in cages next to other ferrets, sharing nothing but the air they breathed.
The experiments showed that the ferrets with swine flu strains lost more weight than those with normal flu, and that the swine flu reached lower down into the lungs of some of the ferrets than normal seasonal flu, penetrating the intestines in some cases.
This tallies with observations in humans that some patients suffered vomiting and diarrhoea. A second study by Ron Fouchier at the Erasmus University Medical Center, Rotterdam, the Netherlands, and his colleagues also showed that the virus penetrated the lungs. "This is the first indication of how pathogenic [swine flu] really is," says Fouchier. "In the field that conclusion is hard to draw."
The warning – that scientists don’t think this new virus has fully adapted to humans yet – is a reminder that flu viruses are constantly changing and capable of producing varying levels of illness.
The virus we are dealing with today may not be the virus we will be dealing with next month, or next year.
