Spanish Flu: 100 years since the breakout of a world epidemic

Spanish Flu: 100 years since the breakout of a world epidemic - This year marks 100 years since Spanish flu ravaged the world's population, killing over 50 million people.

Many countries in Europe were engaged in the First World War at the time. Although the exact origin of the virus is unknown, it's likely that the trench warfare which kept millions of young men crammed in such close quarters together helped the devastating spread of Spanish flu.

Scroll through the gallery to learn more about the epidemic which wiped out almost 5% of the world's population.

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The flu - In 1918 the world was struck by a disease called Spanish flu.

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Origin - The geographic origin of the flu pandemic of 1918-1919 is unknown.

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A disease with many names - It was termed Spanish flu, pneumonic flu, pneumonic plague, or, more simply, pneumonia.

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Name - The name 'Spanish flu' may be due to the fact that the press in Spain, who was not involved in the First World War, wrote freely about the alarming numbers of civilians around the world who were dying from the disease.

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First case - The disease was first recorded in the USA in Fort Riley, Kansas, on March 4 1918, and also in Queens, New York on March 11 of the same year.

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First appearance in Europe - The first cases of the flu recorded in Europe were in April 1918 among French, British and American troops.

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What was happening in the world... - Spanish flu broke out at a time when Europe was still caught in the throes of the First World War.

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Deaths - An estimated 50 million people around the world were killed by the disease, although a lack of records means that this number could be closer to 100 million.

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Deaths in context - This number represented about 5% of the world's population at the time.

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Black Death - The number of deaths caused by Spanish flu is exceeded only by those caused by the black death in medieval times.

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Spanish Flu - To understand better, let's take a closer look at what the Spanish flu was.

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Virus - The Spanish flu virus is an influenza A virus from the subtype H1N1.

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A different strain - Different strains of the flu virus were always potentially fatal, but curiously Spanish flu was most deadly to healthy adults and young people.

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Immunity - Contrary to other strains of influenza which can be fatal for babies, older people and those with weaker immune systems, this flu could kill perfectly healthy individuals.

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Exacerbating factors - A lack of immunity and the confinement of millions of young men in trench warfare are cited as reasons why the disease was able to spread so quickly.

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Genetics - Tests carried out on the virus suggest that it evolved from pathogens affecting birds, and may have jumped straight from the animals to humans.

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Evidence? - Though rearing poultry was very common in Eastern countries, like China, there is no evidence that this happened there before 1918.

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Virus predecessors - However, it's possible that the predecessors of the virus circulated among troops who were deployed across Europe from 1914, when the First World War began.

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Life Expectancy - The pandemic reduced life expectancy in the USA by 12 years.

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High alert! - Because the virus is unpredictable, caution is still necessary! There's nothing to stop the appearance of another pandemic caused by viruses from poultry and swine.

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The world's most deadly epidemics - 429 BC - Athens Plague - 100,000 people killed.

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The world's most deadly epidemics - 541 AD - Plague of Justinian (probably Bubonic Plague) - killed over 45 million people, 40% of the population of the Mediterranean basin.

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The world's most deadly epidemics - 1492 - the arrival of Columbus and the Europeans in the Americas sparked off a wave of disease which wiped out 90% of the indigenous population.

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The world's most deadly epidemics - 1665 - the Great Plague of London - 100,000 people died in the English capital city.

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The world's most deadly epidemics - 1817 - Cholera - this disease's first pandemic spread from India to countries in Asia, Africa and around the Mediterranean basin, killing hundreds of thousands.

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The world's most deadly epidemics - 1918 - Spanish flu - 50 million people lost their lives to this disease.

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The world's most deadly epidemics - 1960 - today - Aids has spread across the globe and has so far killed 35 million people, according to figures from UNAIDS.

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The world's most deadly epidemics - 2009 - H1N1 Virus - killed almost 15,000 people.

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The world's most deadly epidemics - 2013 - 2016 - Ebola - 11,000 people killed in West Africa.

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