The issue with this new swine flu is that it kills those with really effective immune systems..as did the 1918 pandemic.
The influenza strain was unusual in that this pandemic killed many young adults and otherwise healthy victims – wiki
When the immune system is fighting pathogens, cytokines signal immune cells such as T-cells and macrophages to travel to the site of infection. In addition, cytokines activate those cells, stimulating them to produce more cytokines. Normally, this feedback loop is kept in check by the body. However, in some instances, the reaction becomes uncontrolled, and too many immune cells are activated in a single place. The precise reason for this is not entirely understood but may be caused by an exaggerated response when the immune system encounters a new and highly pathogenic invader. Cytokine storms have potential to do significant damage to body tissues and organs.[citation needed] If a cytokine storm occurs in the lungs, for example, fluids and immune cells such as macrophages may accumulate and eventually block off the airways, potentially resulting in death.[citation needed]
The cytokine storm (hypercytokinemia) is the systemic expression of a healthy and vigorous immune system resulting in the release of more than 150 inflammatory mediators (cytokines, oxygen free radicals, and coagulation factors).[citation needed] Both pro-inflammatory cytokines (such as Tumor necrosis factor-alpha, Interleukin-1, and Interleukin-6) and anti-inflammatory cytokines (such as interleukin 10 and interleukin 1 receptor antagonist) are elevated in the serum of patients experiencing a cytokine storm.[citation needed]
Cytokine storms can occur in a number of infectious and non-infectious diseases including graft versus host disease (GVHD), adult respiratory distress syndrome (ARDS), sepsis, avian influenza, smallpox, and systemic inflammatory response syndrome (SIRS).[2]
The first reference to the term cytokine storm in the published medical literature appears to be by Ferrara et al.[3] in GVHD in February 1993.
It is believed that cytokine storms were responsible for many of the deaths during the 1918 influenza pandemic, which killed a disproportionate number of young adults.[1] In this case, a healthy immune system may have been a liability rather than an asset. Preliminary research results from Hong Kong also indicated this as the probable reason for many deaths during the SARS epidemic in 2003.[citation needed] Human deaths from the bird flu H5N1 usually involve cytokine storms as well.
"About 80 per cent of the virus is highly related to a North American body of swine flu that's been around for a number of years, but about 20 per cent of it comes from an Eurasian variety of swine flu first seen in Thailand, so it's recombined to create something totally new."
"Hartl also said 12 of 18 samples taken from victims in Mexico showed the virus had a genetic structure identical to that of the virus found in California earlier this week. But he said the agency needs more information before it changes its pandemic alert level, which currently stands at three on a scale of one to six.
The virus was first reported earlier this week as U.S. health officials scrambled to deal with the diagnoses of seven people with the never-before-seen strain in Texas and California. The states share a border with Mexico not far from a town where two deaths were reported.
Hartl said health officials are dealing with three separate events in Mexico, with most of the cases in and around the capital, Mexico City.
Most of the cases have occurred in healthy young adults, he added."
refs
http://en.wikipedia.org/wiki/Cytokine_storm
http://en.wikipedia.org/wiki/1918_flu_pandemic#History
http://www.alertnet.org/thenews/newsdesk/N23355101.htm
From New scientist and moved up from comments......
The World Health Organization is calling an emergency meeting to decide whether to declare the possible onset of a flu pandemic.
Ironically, after years of concern about H5N1 bird flu, the new flu causing concern is a pig virus, of a family known as H1N1.
Flu viruses are named after the two main proteins on their surfaces, abbreviated H and N. They are also differentiated by what animal they usually infect. The H in the new virus comes from pigs, but some of its other genes come from bird and human flu viruses, a mixture that the US Centers for Disease Control and Prevention calls "very unusual".
On Wednesday, the CDC announced that routine surveillance had uncovered mild flu cases during late March and April, caused by a novel swine flu virus. Those affected, aged 9 to 54, live in and around San Diego, California, and San Antonio, Texas, near the Mexican border. None was severe. Symptoms were normal for flu, with more nausea and diarrhoea than usual.
Mongrelised mix
On Thursday, Canadian public health officials warned Canadians travelling to Mexico of clusters of severe flu-like illness there. Then on Friday the WHO in Geneva said in a statement there have been around 900 suspected cases of swine flu in Mexico City and two other regions of Mexico, with around 60 suspected deaths. Of those, 18 have been confirmed as H1N1 swine flu, says the WHO, and tests so far have shown that 12 of those are "genetically identical" to the California virus.
On Friday, Richard Besser, head of the CDC, confirmed that Mexican samples tested at CDC were also "similar" to the US virus. "From everything we know to date, this virus appears to be the same," he said.
To be declared a pandemic, Besser said, the virus must be new, cause severe disease, and transmit easily enough to be sustained.
It is new. Anne Schuchat, head of science and public health at the CDC, said that the US virus is an unusually mongrelised mix of genetic sequences from North American pigs, Eurasian pigs, birds and humans. The H protein on its surface, having hitherto circulated only in pigs, is one most human immune systems have never seen, the crucial requirement for a pandemic flu.
Too late to contain
The virus's severity will depend on how many people who catch it die. While suspect deaths in Mexico are being tested for H1N1, is not yet known how many mild cases of virus there may have been in the affected region that have gone untested. Both numbers are needed to calculate how deadly a case might be. One ominous sign, however, is that the Mexican cases are said to be mainly young adults, a hallmark of pandemic flu.
It can transmit among people. Those infected in the US had no known contact with pigs, and the three separate clusters of cases did not contact each other. This suggests, said Besser, that "this virus has already been transmitted from person to person, for several cycles", making it too late for emergency antiviral drugs to contain its spread to a limited area.
'High concern'
"Because there are human cases associated with an animal influenza virus, and because of the geographical spread of multiple community outbreaks, plus the somewhat unusual age groups affected, these events are of high concern," the WHO said.
CDC scientists are now examining people with current and recent flu-like illnesses in the areas of California and Texas affected to see how many contacts of known cases have traces of the virus, or antibodies to it. That should show how many cases there may have been, how readily the virus spreads, and how likely it is to maintain transmission.
Another H1N1 flu jumped from pigs to people in 1976, and killed an army recruit in New Jersey. The US went on high alert and vaccinated thousands of people – but the virus did not spread readily enough to maintain an epidemic, and fizzled out.
http://www.newscientist.com/article/dn17025-deadly-new-flu-virus-in-us-and-mexico-may-go-pandemic.html
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The World Health Organization is calling an emergency meeting to decide whether to declare the possible onset of a flu pandemic.
ReplyDeleteIronically, after years of concern about H5N1 bird flu, the new flu causing concern is a pig virus, of a family known as H1N1.
Flu viruses are named after the two main proteins on their surfaces, abbreviated H and N. They are also differentiated by what animal they usually infect. The H in the new virus comes from pigs, but some of its other genes come from bird and human flu viruses, a mixture that the US Centers for Disease Control and Prevention calls "very unusual".
On Wednesday, the CDC announced that routine surveillance had uncovered mild flu cases during late March and April, caused by a novel swine flu virus. Those affected, aged 9 to 54, live in and around San Diego, California, and San Antonio, Texas, near the Mexican border. None was severe. Symptoms were normal for flu, with more nausea and diarrhoea than usual.
Mongrelised mix
On Thursday, Canadian public health officials warned Canadians travelling to Mexico of clusters of severe flu-like illness there. Then on Friday the WHO in Geneva said in a statement there have been around 900 suspected cases of swine flu in Mexico City and two other regions of Mexico, with around 60 suspected deaths. Of those, 18 have been confirmed as H1N1 swine flu, says the WHO, and tests so far have shown that 12 of those are "genetically identical" to the California virus.
On Friday, Richard Besser, head of the CDC, confirmed that Mexican samples tested at CDC were also "similar" to the US virus. "From everything we know to date, this virus appears to be the same," he said.
To be declared a pandemic, Besser said, the virus must be new, cause severe disease, and transmit easily enough to be sustained.
It is new. Anne Schuchat, head of science and public health at the CDC, said that the US virus is an unusually mongrelised mix of genetic sequences from North American pigs, Eurasian pigs, birds and humans. The H protein on its surface, having hitherto circulated only in pigs, is one most human immune systems have never seen, the crucial requirement for a pandemic flu.
Too late to contain
The virus's severity will depend on how many people who catch it die. While suspect deaths in Mexico are being tested for H1N1, is not yet known how many mild cases of virus there may have been in the affected region that have gone untested. Both numbers are needed to calculate how deadly a case might be. One ominous sign, however, is that the Mexican cases are said to be mainly young adults, a hallmark of pandemic flu.
It can transmit among people. Those infected in the US had no known contact with pigs, and the three separate clusters of cases did not contact each other. This suggests, said Besser, that "this virus has already been transmitted from person to person, for several cycles", making it too late for emergency antiviral drugs to contain its spread to a limited area.
'High concern'
"Because there are human cases associated with an animal influenza virus, and because of the geographical spread of multiple community outbreaks, plus the somewhat unusual age groups affected, these events are of high concern," the WHO said.
CDC scientists are now examining people with current and recent flu-like illnesses in the areas of California and Texas affected to see how many contacts of known cases have traces of the virus, or antibodies to it. That should show how many cases there may have been, how readily the virus spreads, and how likely it is to maintain transmission.
Another H1N1 flu jumped from pigs to people in 1976, and killed an army recruit in New Jersey. The US went on high alert and vaccinated thousands of people – but the virus did not spread readily enough to maintain an epidemic, and fizzled out.