At this time of year, the influenza virus is a common talking point. The NHS is desperately trying to get flu vaccinations done. The echoes of coughs and sneezes ring through lecture theatres. Family members are feeling peaky. News outlets exploit the season every year, running endless stories claiming that this could be the worst flu season ever. For many scientists, however, this year offers a more reflective view of the influenza virus as 2018 marks the centenary of the 1918 flu pandemic.
The horror facing the world in 1918 seems quite unimaginable now. Droves of men and boys had been recruited to join the battlefields of World War I. Many would not return, even as it was drawing to a close. For those that did, there was yet another danger waiting for them around the corner. Spanish flu, so-called because Spanish media was the only uncensored, reliable reporting of the disease in Europe at the time, killed an estimated 50 to 100 million people worldwide. To put this figure into context, it represents three to five per cent of the world’s population at the time. It is higher than the total number of military and civilian casualties resulting from the war itself.
In the 100 years since the outbreak of Spanish flu, the scientific community has learnt an incredible amount about the influenza virus. The structure of it, how it replicates, which birds or pigs or other animals it can come from. Scientists are still a long way from knowing everything, but they know a lot more than they did. However, they still don’t know why the outbreak was as shockingly lethal as it was.
It is possible that the quality of life for the majority of people was so poor that they could not fight the virus off. Hospitals were also stretched horribly thin across much of the world, trying to provide care for the flu-infected at the same time as gunshot wounds and gas victims couldn’t have been easy. These factors all could have contributed to the mortality of the disease.
The historical factors are no doubt important but in addition, 1918 flu seems to have had some particularly nasty biological factors. Usually, bad flu outbreaks will affect those that are slightly weaker or are particularly young or old. Those in the middle age range of 20-40, with normally healthy constitutions, will be fine. In 1918, however, this was reversed. A very large proportion of the fatalities from Spanish flu were young to middle-aged as well as fit and healthy.
It is theorised that the virus was as deadly as it was because it overstimulated the immune system and caused what is known as a ‘cytokine storm’. This causes an unmanageable level of inflammation in the body, so it shuts down. The virus could use the immune system against itself. Overstimulate a very active immune system versus an inactive one and the latter patient would, surprisingly, be the survivor.
As the World Health Organisation (WHO) places a new influenza virus as the biggest risk to human life in the world, the 1918 flu virus casts a long shadow. Since then, other viruses have crossed the barrier from infecting only animals to infecting humans too. Some of these sparked pandemics (such as the 2009 Swine flu outbreak) but none have been quite so lethal. The world would not be able to cope with repetition of the events of 100 years ago – hopefully, it won’t have to.
Image: ben dalton via Flickr