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*flourishes notes*
Wow, bird flu really WILL kill us all.
And here's why! Because I believe in public education as the highest priority of international health, and because okay, not everyone is insane like me and prowls around the WHO website keeping track of the latest recorded cases, but this stuff is so interesting.
*pauses*
YA RLY
This is the last two or so pages of my influenza notes. I skipped all the stuff about antigenic shift and clinical symptoms and the Spanish flu.
Since January 2004, events affecting human and animal health have brought the world closer to an influenza pandemic. Many scientists believe that it is only a matter of time until the next flu pandemic occurs.
Avian influenza is an infectious disease of birds caused by the type A strains of the influenza virus; there are 16 subtypes of the virus known to infect birds. To date, all outbreaks of the highly pathogenic form have been caused by influenza A viruses of the subtypes H5 and H7. Migratory waterfowl are a natural reservoir of avian influenza viruses; they can be infected but entirely unsymptomatic, and domestic poultry are particularly susceptible to epidemics of rapidly fatal influenza due to direct or indirect contact with these migratory birds. In April 2005, in China, 6000 wild birds died of a very pathogenic strain – this is very unusual, as normally it is only the domestic ones to die! Live bird markets have also played an important role in the spread of epidemics. Standard control measures include the quarantining of infected farms and the destruction of infected or potentially exposed flocks. Highly pathogenic viruses, however, can survive for long periods in the environment.
Avian influenza viruses do not normally infect species other than birds and pigs. The first documented infection of humans with an avian flu virus occurred in Hong Kong in 1997. The response was the rapid destruction of the entire poultry population of Hong Kong within three days, which likely stopped a pandemic. In January 2004, laboratory tests proved the presence of H5N1 avian flu virus in human cases of sever respiratory disease in the northern part of Vietnam. In humans, H5N1 affects the lower respiratory tract rather than the higher, due to the type of receptor on the cells, so it is very unlikely that humans will be able to spread it to other humans unless the virus mutates so that it can infect the higher human respiratory tract. So far there has been one case of suspected human-to-human transmission, in February of 2005.
H5N1 is of particular concern because:
• It mutates rapidly
• It has the propensity to acquire genes from flu viruses infecting other animals
• It has high pathogenicity (high mortality rate in humans)
• Birds surviving infection excrete the virus orally or through faeces for at least 10 days
• If humans become a ‘mixing vessel’, there is the possibility of the emergence of a novel subtype with the characteristics of the human and avian flu viruses – pandemic!
The principal sources of human infection are:
• Close contact with dead or sick birds such as slaughtering, defeathering and butchering
• Exposure to infected poultry faeces
It is hard to avoid – ducks can look healthy, and still be carriers.
The H5N1 virus is now endemic in parts of Asia, having established a permanent ecological niche in poultry, and it is both becoming more resilient (surviving longer in the environment) and extending its mammalian range to domestic cats and dogs in affected areas. The risk of further human cases will continue, as will the opportunity for a pandemic virus to emerge; no virus of the H5 subtype has probably ever circulated among human beings – and certainly not within the lifetime of today’s world population – so population vulnerability to an H5N1-like virus is universal. Influenza also has a short incubation period and can be transmitted before symptoms, unlike SARS, so it would be difficult to contain. H5N1 is resistant to some antiviral drugs, but not yet resistant to Tamiflu; this would be our first line of defense against an epidemic, but we don’t have nearly enough for adequate global supply.
The World Healh Organisation’s expectations for the next flu pandemic are:
• Rapid spread due to the high level of global traffic
• Short supply and unequal distribution of vaccines, antiviral drugs and other treatments
• Vaccine production will take several months, as we can’t design a vaccine until the pandemic strain is known and isolated, which cannot be done until it emerges!
• Medical facilities will be overwhelmed
• There will be a shortage of personnel providing essential community services
• Prolonged effects: outbreaks are expected to reoccur
The WHO 5 priority actions:
• Reduction of human exposure to H5N1, including education about risky behaviours
• Strengthening of early warning systems – a plan for the pandemic is needed
• Intensifying rapid containment operations
• Building of coping capacity – the WHO has a document of recommendations
• Coordination of global research, as occurred with SARS genome sequencing – less of a race-to-publish competition
Even in the best case scenarios of the next pandemic, 2-7 million people would die and tens of millions would require medical attention. If the next pandemic virus is a very virulent strain, deaths could be dramatically higher (up to 50 million deaths) and it could cost US$800 billion within a year. The window of opportunity for us to prevent such a pandemic has been estimated as 3 weeks from the infection of the first case – prevention is preferable.
Controlling the virus in poultry was recognized as the best way to reduce the current pandemic risk, but factors such as financial compensation for the farmers whose birds are culled must be considered – without it, the farmers would lose everything, and so they would be much less likely to report an outbreak if one occurs. (Financial strain also creates the problem of pigs and birds/more than one bird species living in close contact, as families rely on multiple sources of income.)
Africa is especially ill equipped to fight a bird flu epidemic, if one occurs:
• Poverty, war (less money for health) and sickness (which makes the population more susceptible to infection and illness
• Weak public health and veterinary facilities
• Burden from other diseases, which could also mask H5N1 human cases
• High levels of AIDS, which will likely mean a greater impact of the virus
~
Doesn't it just make you want to run off and join the WHO?
Just me, then.
And here's why! Because I believe in public education as the highest priority of international health, and because okay, not everyone is insane like me and prowls around the WHO website keeping track of the latest recorded cases, but this stuff is so interesting.
*pauses*
YA RLY
This is the last two or so pages of my influenza notes. I skipped all the stuff about antigenic shift and clinical symptoms and the Spanish flu.
Since January 2004, events affecting human and animal health have brought the world closer to an influenza pandemic. Many scientists believe that it is only a matter of time until the next flu pandemic occurs.
Avian influenza is an infectious disease of birds caused by the type A strains of the influenza virus; there are 16 subtypes of the virus known to infect birds. To date, all outbreaks of the highly pathogenic form have been caused by influenza A viruses of the subtypes H5 and H7. Migratory waterfowl are a natural reservoir of avian influenza viruses; they can be infected but entirely unsymptomatic, and domestic poultry are particularly susceptible to epidemics of rapidly fatal influenza due to direct or indirect contact with these migratory birds. In April 2005, in China, 6000 wild birds died of a very pathogenic strain – this is very unusual, as normally it is only the domestic ones to die! Live bird markets have also played an important role in the spread of epidemics. Standard control measures include the quarantining of infected farms and the destruction of infected or potentially exposed flocks. Highly pathogenic viruses, however, can survive for long periods in the environment.
Avian influenza viruses do not normally infect species other than birds and pigs. The first documented infection of humans with an avian flu virus occurred in Hong Kong in 1997. The response was the rapid destruction of the entire poultry population of Hong Kong within three days, which likely stopped a pandemic. In January 2004, laboratory tests proved the presence of H5N1 avian flu virus in human cases of sever respiratory disease in the northern part of Vietnam. In humans, H5N1 affects the lower respiratory tract rather than the higher, due to the type of receptor on the cells, so it is very unlikely that humans will be able to spread it to other humans unless the virus mutates so that it can infect the higher human respiratory tract. So far there has been one case of suspected human-to-human transmission, in February of 2005.
H5N1 is of particular concern because:
• It mutates rapidly
• It has the propensity to acquire genes from flu viruses infecting other animals
• It has high pathogenicity (high mortality rate in humans)
• Birds surviving infection excrete the virus orally or through faeces for at least 10 days
• If humans become a ‘mixing vessel’, there is the possibility of the emergence of a novel subtype with the characteristics of the human and avian flu viruses – pandemic!
The principal sources of human infection are:
• Close contact with dead or sick birds such as slaughtering, defeathering and butchering
• Exposure to infected poultry faeces
It is hard to avoid – ducks can look healthy, and still be carriers.
The H5N1 virus is now endemic in parts of Asia, having established a permanent ecological niche in poultry, and it is both becoming more resilient (surviving longer in the environment) and extending its mammalian range to domestic cats and dogs in affected areas. The risk of further human cases will continue, as will the opportunity for a pandemic virus to emerge; no virus of the H5 subtype has probably ever circulated among human beings – and certainly not within the lifetime of today’s world population – so population vulnerability to an H5N1-like virus is universal. Influenza also has a short incubation period and can be transmitted before symptoms, unlike SARS, so it would be difficult to contain. H5N1 is resistant to some antiviral drugs, but not yet resistant to Tamiflu; this would be our first line of defense against an epidemic, but we don’t have nearly enough for adequate global supply.
The World Healh Organisation’s expectations for the next flu pandemic are:
• Rapid spread due to the high level of global traffic
• Short supply and unequal distribution of vaccines, antiviral drugs and other treatments
• Vaccine production will take several months, as we can’t design a vaccine until the pandemic strain is known and isolated, which cannot be done until it emerges!
• Medical facilities will be overwhelmed
• There will be a shortage of personnel providing essential community services
• Prolonged effects: outbreaks are expected to reoccur
The WHO 5 priority actions:
• Reduction of human exposure to H5N1, including education about risky behaviours
• Strengthening of early warning systems – a plan for the pandemic is needed
• Intensifying rapid containment operations
• Building of coping capacity – the WHO has a document of recommendations
• Coordination of global research, as occurred with SARS genome sequencing – less of a race-to-publish competition
Even in the best case scenarios of the next pandemic, 2-7 million people would die and tens of millions would require medical attention. If the next pandemic virus is a very virulent strain, deaths could be dramatically higher (up to 50 million deaths) and it could cost US$800 billion within a year. The window of opportunity for us to prevent such a pandemic has been estimated as 3 weeks from the infection of the first case – prevention is preferable.
Controlling the virus in poultry was recognized as the best way to reduce the current pandemic risk, but factors such as financial compensation for the farmers whose birds are culled must be considered – without it, the farmers would lose everything, and so they would be much less likely to report an outbreak if one occurs. (Financial strain also creates the problem of pigs and birds/more than one bird species living in close contact, as families rely on multiple sources of income.)
Africa is especially ill equipped to fight a bird flu epidemic, if one occurs:
• Poverty, war (less money for health) and sickness (which makes the population more susceptible to infection and illness
• Weak public health and veterinary facilities
• Burden from other diseases, which could also mask H5N1 human cases
• High levels of AIDS, which will likely mean a greater impact of the virus
~
Doesn't it just make you want to run off and join the WHO?
Just me, then.
no subject
Other things you may already know that I found particularly interesting:
* The last three pandemics ("Spanish" flu, 1918-9, H1N1; "Asian" flu, 1957-8, H2N2; and "Hong Kong" flu, 1968-9, H3N2) ALL involved a virus that combined both human and avian strains. ALL of them. This is why everyone's worried about panflu now.
* What they have for a vaccine currently against H5N1 indicates the need for increased dosage and efficacy is only 54%. Hollow laugh.
* Relenza, like Tamiflu, is a neuraminidase inhibitor, and that seems to be the key to efficacy right now. Stockpiling is already a problem, and that's not even considering those countries suffering from extreme health inequity/inequality situations.
*And here's the one that made me sit bolt upright in my chair -- did you hear about the Indonesia situation? May 22 is the date I have in my notes. Last I heard, they were calling it confirmed human --> human transmission. The index case worked with chickens, and 7 family members came down with H5N1 about 5-6 days later. None of them had any known contact with birds, and the incubation rate etc. indicates secondary transmission rather than the primary exposure to birds. So, index plus seven equals eight cases total.
Seven were fatal.
... see you over at the WHO, then. :) Me, I'm eyeing local response teams (some interesting projects around here), as well as the CDC, among other things.
no subject
Have you read the "bible" -- or so I keep hearing it called? "Stand on Guard for Thee," which is a report from the University of Toronto Joint Centre for Bioethics' Pandemic Influenza Working Group. It's pretty interesting, and came in large part out of things learned from the response to SARS -- and as we all know, Toronto had some serious practical experience with SARS.
(I happened to travel through the Toronto airport near the end of the SARS outbreak. Fascinating experience.)
AHA, I found a link to a PDF from a reliable source that looks to match my copy! Here you go.
no subject
And...hmm, I have it in my notes that in 2005 a lab reconstruction showed that the Spanish flu strain was actually a mutation of a purely avian strain that adapted to humans, not a hybrid virus.
I hadn't heard about the Indonesian cases O_O I just know about the family in Thai Binh who all caught it and probably gave it to a nurse. Nobody died, though.
no subject
Doctor Who, that is.
I'll see you in the fifty-first century, baby!
no subject
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I'll just be under my bed, if anyone needs me. Just push the buzzer next to the deadbolt and stand in the red circle marked QUARANTINE. We can talk through the window.
no subject
*throws facemasks and tinned food at you*
no subject
*catches facemasks, looks up, dives for cover*
You have made progress on your list, I see! Save us plz. You and Obi Wan are our only hope. :(