Thursday, August 25, 2005
H5N1: FAQ
I compiled a FAQ on the subject for my own reference. You may find it useful.
1. Why the urgency now?
When doctors announced the deaths of 6 people in Hong Kong from a new form of flu (H5N1) in 1997, it made few headlines. The jump across the species barrier was a surprise, but the outbreak seemed like a storm in a distant teacup.
Since the Hong Kong outbreak, the H5N1 virus has spread across Asia and infected another 100 or so people, killing around half. So far, all the victims appear to have contracted the virus after direct exposure to birds.
But now the same virus has turned up in many places. Last week Russian scientists revealed that thousands of domestic birds around the Chelyabinsk region of the Ural mountains had perished after contracting H5N1, which had apparently been transported there by migrating birds.
2. What is the good news?
The virus has so far failed to repeat the feat it first achieved in Hong Kong (infecting 18 killing 6 in a short time before it disappeared in HongKong), There is only one probable human-to-human transmission. The bad news is that many experts think that it is only a matter of time before it succeeds.
3. How likely is human-to-human transmission?
Each time the virus succeeds in infecting humans, it increases the chances of triggering the nightmare scenario: human-to-human transmission. The consequences could hardly be more worrying. Some scientists are already drawing parallels with the so-called Spanish Flu outbreak of 1918, in which another bird flu virus - code-named H1N1 - hit the right genetic combination needed to trigger human-to-human transmission. The resulting pandemic led to at least 20 million deaths, double the number of people killed in the First World War.
4. What is the advice from experts?
Prof Neil Ferguson, an expert on virus epidemics at Imperial College, London advised that "The 1918 scenario is within what people should be planning for." Such an epidemic is most likely to start once the H5N1 virus infects someone already harbouring standard human flu. "Then the two viruses can recombine to produce a type capable of human-to-human transmission," he says. "We're worried because this bird virus is so lethal. It kills 50 per cent of those infected at the moment, though that could change once it gets into humans." [The virus responsible for the 1918 pandemic killed only a few per cent of those it infected.]
Last week the World Health Organisation (WHO) made clear its concern about the spread of H5N1 beyond south-east Asia. It called for close surveillance of the situation in Russia, and checks on respiratory patients who may have been exposed to sick birds. It has begun negotiations to stockpile anti-viral drugs, which both reduce the symptoms of those already infected and provide some protection against the virus.
British Health Officials pointed out that any vaccine based on the current strain of H5N1 could prove useless against a human-to-human version.
Despite the efforts to avert a pandemic, many experts remain sanguine about our ability to cope with the threat. They point out that the virus is still confined almost entirely to the bird population, making control of an outbreak relatively simple. As soon as tests confirm the presence of the virus in a flock, the plan of action is dramatic and draconian: rapid and massive culling. The strategy stopped the original Hong Kong outbreak in 1997. It also halted an outbreak of the H7N7 bird flu, which also infected humans, in Holland in 2003.
5. What is my take on the situation?
Some comfort can come from considering the following facts:
1. Why the urgency now?
When doctors announced the deaths of 6 people in Hong Kong from a new form of flu (H5N1) in 1997, it made few headlines. The jump across the species barrier was a surprise, but the outbreak seemed like a storm in a distant teacup.
Since the Hong Kong outbreak, the H5N1 virus has spread across Asia and infected another 100 or so people, killing around half. So far, all the victims appear to have contracted the virus after direct exposure to birds.
But now the same virus has turned up in many places. Last week Russian scientists revealed that thousands of domestic birds around the Chelyabinsk region of the Ural mountains had perished after contracting H5N1, which had apparently been transported there by migrating birds.
2. What is the good news?
The virus has so far failed to repeat the feat it first achieved in Hong Kong (infecting 18 killing 6 in a short time before it disappeared in HongKong), There is only one probable human-to-human transmission. The bad news is that many experts think that it is only a matter of time before it succeeds.
3. How likely is human-to-human transmission?
Each time the virus succeeds in infecting humans, it increases the chances of triggering the nightmare scenario: human-to-human transmission. The consequences could hardly be more worrying. Some scientists are already drawing parallels with the so-called Spanish Flu outbreak of 1918, in which another bird flu virus - code-named H1N1 - hit the right genetic combination needed to trigger human-to-human transmission. The resulting pandemic led to at least 20 million deaths, double the number of people killed in the First World War.
4. What is the advice from experts?
Prof Neil Ferguson, an expert on virus epidemics at Imperial College, London advised that "The 1918 scenario is within what people should be planning for." Such an epidemic is most likely to start once the H5N1 virus infects someone already harbouring standard human flu. "Then the two viruses can recombine to produce a type capable of human-to-human transmission," he says. "We're worried because this bird virus is so lethal. It kills 50 per cent of those infected at the moment, though that could change once it gets into humans." [The virus responsible for the 1918 pandemic killed only a few per cent of those it infected.]
Last week the World Health Organisation (WHO) made clear its concern about the spread of H5N1 beyond south-east Asia. It called for close surveillance of the situation in Russia, and checks on respiratory patients who may have been exposed to sick birds. It has begun negotiations to stockpile anti-viral drugs, which both reduce the symptoms of those already infected and provide some protection against the virus.
MOH has also drawn up strategies to combat H5N1 and made contingency plans for dealing with an outbreak [reference MOH website.]
British Health Officials pointed out that any vaccine based on the current strain of H5N1 could prove useless against a human-to-human version.
Despite the efforts to avert a pandemic, many experts remain sanguine about our ability to cope with the threat. They point out that the virus is still confined almost entirely to the bird population, making control of an outbreak relatively simple. As soon as tests confirm the presence of the virus in a flock, the plan of action is dramatic and draconian: rapid and massive culling. The strategy stopped the original Hong Kong outbreak in 1997. It also halted an outbreak of the H7N7 bird flu, which also infected humans, in Holland in 2003.
5. What is my take on the situation?
Some comfort can come from considering the following facts:
- There have been 60 to 70 human deaths out of several billion in Asia. There are many more deaths on Bangkok's roads over Songklan Holidays (2 or 3 days).
- This virus has had lots of opportunities across Asia to mutate but hasn't, so the probability must really be very low.
On the other hand, any contingency plan we may want to put in place would take time to complete. I would strongly recommend that we pay some attention to the possibility of a bird flu pandemic now. For example taking stock of what we already have in place and identify what else might be needed should such bird flu strikes. Moreover, bird flu is just a good focus/frame for planning. Even if it doesn't turn into a pandemic, the plan we have in place would make us more resilient.
