Since 2005, in an impressive if somewhat chilling feat, American researchers have “resurrected” the particular variant of influenza responsible for the deadliest pandemic ever, the 1918 Spanish flu pandemic. The achievement was initially announced in the important scientific publication Nature in October 2005 under the fitting headline, “The 1918 Flu Virus is Resurrected.”
Influenza is a common but serious illness. Although the majority of people exposed develop a troubling but non-threatening respiratory illness (not to be confused with the so-called stomach flu), potential complications include life-threatening pneumonia, and as many as half a million people are killed by the flu every year. More troubling, the flu has several host species, including not just humans but pigs (swine flu) and chickens (avian flu or bird flu). Every so often one form of the virus jumps between species, bringing with it a host of new adaptations against which the new victims have very little or no immune protection. This can lead to pandemics, the most recent of which (and, fortunately, one of the least serious of which) was the 2009 H1N1 flu pandemic.
By far the most deadly of flu pandemics in recorded history began in 1918, at the close of the First World War. The so-called Spanish flu reached around the globe, killing about 50 million people or 3% of the entire global population in just two years – making it more deadly than the entire world war. It actually seems to have begun in American soldiers, but was named after Spain largely because the lack of press censorship in that neutral country resulted in widespread coverage of some of the first high-profile cases. The disease progressed extremely quickly, leading to pneumonia and potentially death. It is this worst-case scenario which has animated fears over potential new flu pandemics today.
The 2005 research which resurrected the 1918 flu strain therefore represented an important breakthrough in medical history. The U.S. Armed Forces Institute of Pathology, based in Maryland, reconstructed the flu by piecing together its genetic code from the frozen remains of hospital specimens and a single flu victim in Alaska, where permafrost – the mixture of ice and dirt which lies beneath the ground in the Arctic Circle – means that buried bodies can be frozen rather than left to deteriorate. The research team was able to piece together a full copy of the virus, and then sequence its genome – a little less than one-half of which was published in the original Nature piece. That work allowed another team, at the Centers for Disease Control (CDC), to complete the reconstruction of the virus, leading to a live version which they were able to inoculate mice with.
This research has some chilling implications (given fears about the future of bioterrorism), but is also extremely important medically, especially when fears remain over the uncertain future of H5N1 avian flu – which some have fingered as the most likely source of a serious future pandemic. Researchers have been able to identify some unique features of the Spanish flu virus which appear to make it especially deadly. This will allow them to identify troubling types of mutations associated with more deadly viruses, and thus to track with more accuracy the evolution of potentially serious strains of flu virus in the wild. It would even be possible to develop a vaccine against the Spanish flu, given sufficient effort, but this is currently unnecessary, since the Spanish flu as such is no longer a public health threat.
