If the doomsayers are to be believed, the humble chicken may soon bring about the downfall of mankind. No longer will chickens be the butts of jokes, as the threat is considered more deadly than terrorist attacks, more pressing than the dangers posed by global climate change; Vietnamese poultry are working on our undoing as we speak.
More precisely H5N1, the particular influenza virus they carry poses the threat. Birds are the source of the vast majority of new human influenza strains, and theclose proximity in which people live with poultry in much of East Asia puts the region at highest risk of a viral species jump.
History suggests the doomsayers may have a point. The last pandemic influenza outbreak, ‘Spanish flu’ swept the world in 1918, and was the most devastating disease ever recorded. Estimates for the total worldwide death toll top 50 million, making the First World War seem like a minor bun fight in comparison.
With the global population having more than tripled since, the potential consequences of a new uncontrolled outbreak are unimaginable. Even more chilling, Spanish flu was fatal in only around 1 – 2% of its victims; as many as 60% of those that have caught H5N1 from poultry have died.
All a virus requires to cause disease is a way into our cells, so that the instructions they carry can commandeer the cellular machinery for their own ends. Such a simple toolkit means that the molecules that allow them in can evolve quickly; small changes make little difference to the fundamental processes. Rapid viral evolution is the reason that both science and Mother Nature in the form of a complex immune system are in a never-ending arms race against influenza. It’s also the reason that nobody has yet been able to come up with a catch-all cure for the common cold and thus why I feel like death today.
This rapid evolutionary capability also facilitates the regular species jumps made by influenza viruses from their natural habitat in birds. Proof of the danger this principle presents was amply given in recently published work which showed that very minor changes to the three-dimensional structure of the viral proteins that bind the cell surface allowed Spanish flu to pass into human populations.
Of course, flu is not the only disease to cross species. Just as Flu once caused death on a huge scale, the current AIDS epidemic highlights the versitality of the disease. HIV for example, is the human form of Simian Immunodeficiency Virus, a relatively innocuous suite of infections endemic in many African primate populations. It’s likely that it was transmitted to humans through bush meat or close contact (no, not bestiality) where it mutated to cause the current AIDS epidemic. Meanwhile it’s unknown whether CJD, originally BSE in cattle can be transmitted between humans, but you won’t find the National Blood Service taking any chances.
Known instances of direct transmission between people are the only faculty H5N1 lacks to satisfy the World Health Organisation’s criteria for a global killer pandemic, an eventuality it now describes as “inevitable”. The strain has been closely tracked in birds and human cases have been scrupulously recorded and quarantined for fear of the as-yet unobserved intra-species transmission. But as the top influenza expert Professor John Oxford often points out, “The big time bomb here is that once there is 100% evidence of human to human spread it will be too late to do anything about it. Once it starts it’s likely to move quickly.”
Little surprise then that the calls for plans to be put in place for an outbreak have been growing ever louder since the H5N1 strain was first identified in 1997. The UK government has faced criticism for being slow to respond to the potential pandemic, but is now expected to announce a full action plan in the coming weeks.
The French, Italian and US governments have placed orders with manufacturers to begin stockpiling a prototype vaccine that can quickly be adapted to whatever final form the pandemic virus will take. Antiviral drugs to abate the effects of the infection are also already in high demand from First World governments. It’s thought that the UK government has not yet put any such orders in place.
Sceptics and optimists point to parallels with another recent newly emergent disease. The SARS outbreak was also thought to have originated through close contact with farm animals in East Asia, and warnings a global pandemic were made then too.
A strategy of containment was adopted, and worked: the only cases of SARS known now are found in laboratory culture. Predictions of a New World Order thanks to crippled social and economic infrastructures post-H5N1 gain some much needed perspective in this light. However, complacency likewise is not an option when faced with a time bomb.
The seriousness of this threat cannot be ignored. In the meantime the world will have to prepare, watch and worry. Not to mention another good reason to avoid the geese on campus.