Swine Flu - a triumph for science

Influenza pandemics happen about three times in a century. At least this is what 20th century history teaches us. There was the big Spanish Flu of 1918 (which did'nt really start from Spain), which infected an estimated third of the human population at that time and killed 40 to 50 million people. Then, there were the Asian Flu of 1957 and the Hong Kong Flu of 1968, each killing an estimated 1 million persons each.

Historically we were due for another big one. Is this the one? The swine flu (again a misnomer) started in Mexico around March of this year and has gone around the world, prompting WHO to raise its alert to Level 6, the first time in over 30 years. As of September 6, 2009, this disease has infected over 277,000 persons and killed at least 3200 (see http://www.who.int/csr/don/2009_09_11/en/index.html). If you believe that in infectious diseases you only see the tip of the iceberg, there are many more infections and deaths that have gone unrecorded. And we are just getting into the flu season in the Northern hemisphere.

So far this virus appears to be mild. It has killed about 1% of infected people, many of whom had underlying problems such as asthma, diabetes, hypertension and obesity. Yes, obesity! Thats a new one positively identified for this virus. But will it remain mild? No one knows. History tells us otherwise.

The 'Spanish flu' started as a mild infection in the summer of 1918, spread rapidly and the virus got a lot of chance to mutate. By November of 1918, the flu season in the Northern hemisphere, it became highly virulent and killed with disdain. We are into a similar situation with this one. It has already gone around the world, including Australia and South America (Southern hemisphere) in their flu season, and is getting a lot of chance to transmit and mutate. Health agencies are already preparing for the 'second wave'. See
http://www.who.int/csr/disease/swineflu/notes/h1n1_second_wave_20090828/en/index.html

Are we then sitting ducks? Or pigs to be more appropriate for this one! Not really. Health systems are much better prepared to handle these emergencies today than they were 90 years ago. The agent for Spanish flu took over 11 years to identify. The 'swine flu' virus was identified in days.

This virus, technically called Influenza A H1N1 (2009), is a triple reassortant. Scientists have traced its 8 different gene segments to influenza viruses that have circulated in humans, birds and pigs (see: Garten et al, Science vol 325, pages 197-201; July 10, 2009). The cartoon below illustrates the lineage of different gene segments in this new virus.
The surface proteins of the virus - the hemeagglutinin (H1) and the neuraminidase (N1), are both of swine origin. This makes the virus new to the human population, not recognized by our immune system. This is obvious from the efficient manner in which it is transmitting between humans.

Every adversity has a lesson. The lesson here is how investments in biomedical science are paying up in unexpected ways. It took just days to identify this virus and weeks to come up with its origins. This is truly the power of molecular biology, built up over years with the Human Genome Project as a very visible high point. Many have criticized that megaproject, but consider that it enabled the development of technology, which is making all this possible. When SARS came around in 2003, the sequencing of its genome was also undertaken in facilities set up for the HGP. Chinese scientists sequenced the SARS virus genome in a facility built to sequence the rice genome! That is a great off-target effect and a lesson for science funders and planners.

Every day dozens of swine flu sequences are being uploaded in public databases (http://www.ncbi.nlm.nih.gov/genomes/FLU/SwineFlu.html). Many scientific journals, normally driven by commercial interests, have made swine flu papers "open access". This uninhibited access to knowledge and the power of internet is bringing the technical prowess of big science closer to where it matters - the hot zone.

Are we really making use of this knowledge in my hot zone - India? Stay tuned.