Facing an uncertain future

The scientific briefing with Luke Boulter

In 1996 a farmed goose in the Guangdong province of China was isolated as the first death from the highly pathogenic Avian Flu virus H5N1 strain. Now this has become synonymous with death, but at the time it was just another virus to be monitored. One year on, the same viral strain infected 18 humans in Hong Kong, 6 of these cases proved to be fatal. Suddenly and quite unexpectedly the virus stopped and for 5 years the H5N1 lay dormant. It is unlikely that it totally died out; rather it probably continued to be transmitted through bird populations. February 2003 showed the re-emergence of H5N1 (commonly known as avian flu type A) when two members of a Hong Kong family contracted the H5N1 strain during a recent stay in China.

This was the start of the first H5N1 wave. The World Heath Organisation (WHO) suggests that between mid-2003 and 8 January 2004 there were regular outbreaks of avian flu throughout Asia. This climaxed with reports of sporadic human infections in Vietnam and Thailand – it was shown that in most cases, the H5N1 virus was contracted from those who work alongside poultry. However there was some evidence to suggest that limited human-to-human contact could result in the transmission of the deadly H5N1 virus. Of the few cases that were recorded, about half of them were fatal.

Viruses can quite happily lie within a host without killing it; an animal acting as a host is known as a reservoir. The normal reservoir for H5N1 was wild waterfowl, however in April 2005 thousands of migratory waterfowl (the natural reservoirs for H5N1) died due to the virus. This suggested that the virus had changed to become more virulent, killing the host in which it can normally hide

Over the proceeding months the virus swept west and in July 2005 was shown to be in both Kazakhstan and some provinces of Siberia. In these regions, large numbers of dead migratory birds were found, confirming the worst fears of global health organisations that the H5N1 virus could be carried along routes of migration. In October 2005 Turkey reported the presence of H5N1 in poultry. January 2006 saw Turkey confirm two human deaths due to H5N1 and another 14 cases of infection. These were the first reports of human fatalities in Europe.

So what is H5N1? It is a virus which consists of a genome (in this case of RNA), which is housed in a shell known as the capsid. It has a membrane coat with about 500 protein spikes sticking out of its surface. About 400 of these are known as Hemagglutinin (HA) and the other 100 are known as Neuraminidase (NA). It is these two molecules which allow the virus to link with cells and hijack the cell machinery in order to recreate themselves. HA and NA change quite rapidly from one viral generation to the next, thanks to mutations in the RNA. This is also due to two different viruses mixing sections of their genetic material – (this is what the numbers proceeding the H and N correspond to; they have type 1 NA and type 5HA). It is because of these rapid changes that a vaccine against flu may not always be successful.

There is a Flu pandemic every few decades. The last one, in 1918, was known as “Spanish Flu” and reconstructions of this virus have shown a remarkable similarity to the H5N1 strain. Spanish Flu killed between 40 and 50 million people (3 per cent of all those infected) before it was contained, with most deaths occuring in slightly more than a year. H5N1 has been around for a while now and recorded cases only total about 150 humans, with only about 60 fatalities. Whilst this suggests that H5N1 has about a 50% fatality, there could be thousands of people not showing symptoms, meaning the actual rate of fatality is considerably lower. To put these numbers onto a scale: 36,000 Americans die from normal human flu each year. In the grand scheme of things, H5N1 is a relatively small killer – it is the future virulence that is to be feared.

There is evidence to show that H5N1 will be less deadly than people presently fear. Scientists in Vietnam, one of the key places infected with the avian virus believe that if the virus begins to spread throughout the population at a slow rate, then the death toll will not be as high as initially predicted. However if it infects large numbers of people who fail to display symptoms, then H5N1 is given a chance to mutate, thus becoming more harmful. There are now reported instances where people who have come into close contact with H5N1 sufferers or those culling poultry are producing antibodies to attack the H5N1 virus.

So, if there was a pandemic of H5N1, what would our options be? Well, initially there are antiviral drugs such as zanamivir, which would prevent the virus from spreading through a population. However, there are reports of antiviral resistant H5N1 strains, which means that this option may not be wholly feasible. If the infection was brought to the UK, some bodies suggest enforced quarantine for those who refuse to take medication or those who fail to respond to treatment. This method has been used with great success in the containment of antibiotic resistant TB in various parts of America. It does, however, result in the removal of choice and invasion of individual human rights.

Ultimately, with $1.9 billion worth of money being put into containment there is little chance that this Flu will strike in the same way the Spanish Flu did in the early 1900s. If all else fails, it has been shown that Sauerkraut and Kinchi (effectively fermented cabbage) can treat H5N1 flu in birds… who knows, maybe it will work for humans too?

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