Past influenza pandemics

Influenza pandemics occur when a new influenza virus emerges and begins spreading as easily from person to person as normal influenza. Pandemics tend to be rare and recurrent. In the twentieth century, the world experienced three influenza pandemics: 1918, 1957, 1968. These three influenza pandemics varied in origin and severity. Since then, the world has experienced one pandemic: 2009

A chart of deaths in major cities from the 1918 influenza pandemic in the US and Europe. (Image: courtesy of the National Museum of Health and Medicine)

Spanish influenza – 1918

Spanish influenza emerged towards the end of World War One, the cramped conditions of military quarters and the mass movement of troops thought to have contributed to its rapid spread.

The exact origin of the pandemic remains unknown however North America and China are suspected possible starting points. The pandemic received considerable attention in Spain compared to the rest of Europe.

The World Health Organisation estimates that half of the world’s population were infected with the Spanish flu and highlights it as one of the deadliest examples of a pandemic.

An estimated 40-50 million deaths occurred worldwide, reflecting a mortality rate of 2-2.5% with adults aged between 20-40 were the most affected.

Asian influenza – 1957

The Asian influenza was first detected in China in February 1957 and had spread globally within 6 months. It was later identified as an avian influenza, type A H2N2.

In Europe the spread of the flu coincided with the end of school holidays, with students returning to school in September. A second wave of the flu occurred in 1958.

Combined, the two waves of the Asian flu affected 40-50% of people and contributed to the death of 1-2 million people, according to the WHO.

Hong Kong influenza - 1968

The Hong Kong influenza had its origins in South East Asia and emerged in China in July of 1968.

The number of cases reported in Hong Kong jumped to 500,000 within 2 weeks of its first detection.The flu reached the United States by September 1968 before extending to Europe.

Approximately 1-3 million people are thought to have died as a result of the Hong Kong influenza according to the WHO.

Swine Flu - 2009

In 2009 Australia experienced an outbreak of H1N1 influenza, commonly known as "Swine flu".

The virus - derived from human, swine and avian strains - was first detected in North America in April 2009 and then spread around the world.

By the time the World Health Organisation declared it a pandemic in June, a total of 74 countries had reported cases of infections.

In Australia, there were 37,636 cases of H1N1 influenza, and 191 deaths. A new study said the pandemic killed approximately 284,500 people worldwide.

Sources:

Department of Health - 'Pandemic Influenza'

World Health Organisation - 'Pandemic Preparedness'

Centers of Disease Control and Prevention - ‘Influenza Pandemics of the 20th Century’

Health Protection Agency, United Kingdom - ‘History of Pandemics’

Related Links:

VIDEO: The Genesis of the 1918 Influenza Pandemic
VIDEO: 1918 Flu Pandemic

VIDEO: The Asian flu arrives in Canada