page_title: Social history of viruses
section_title: Poliomyelitis
hierarchical_section_title: Social history of viruses / 20th and 21st centuries / Poliomyelitis
caption_attribution_description: Deutsch: Krankenhauspersonal untersucht einen Patienten in einer eisernen Lunge während der Rhode-Island-Polio-Epidemie. English: Hospital staff are examining a patient in a tank respirator, iron lung, during the Rhode Island polio epidemic. The iron lung encased the thoracic cavity externally in an air-tight chamber. The chamber was used to create a negative pressure around the thoracic cavity, thereby causing air to rush into the lungs to equalize intrapulmonary pressure. Français&#160;: Patient souffrant de la polio dans un respirateur artificiel à pression négative (poumon d'acier). Nederlands: IJzeren long. Português: "Pulmão de ferro" assistindo doente com paralisia total.
context_page_description: The social history of viruses describes the influence of viruses and viral infections on human history. Epidemics caused by viruses began when human behaviour changed during the Neolithic period, around 12,000 years ago, when humans developed more densely populated agricultural communities. This allowed viruses to spread rapidly and subsequently to become endemic. Viruses of plants and livestock also increased, and as humans became dependent on agriculture and farming, diseases such as potyviruses of potatoes and rinderpest of cattle had devastating consequences.
  Smallpox and measles viruses are among the oldest that infect humans. Having evolved from viruses that infected other animals, they first appeared in humans in Europe and North Africa thousands of years ago. The viruses were later carried to the New World by Europeans during the time of the Spanish Conquests, but the indigenous people had no natural resistance to the viruses and millions of them died during epidemics. Influenza pandemics have been recorded since 1580, and they have occurred with increasing frequency in subsequent centuries.
context_section_description: During the summers of the mid-20th century, parents in the US and Europe dreaded the annual appearance of poliomyelitis (or polio), which was commonly known as "infantile paralysis". The disease was rare at the beginning of the century, and worldwide there were only a few thousand cases per year, but by the 1950s there were 60,000 cases each year in the US alone and an average of 2,300 in England and Wales.
  During 1916 and 1917 there had been a major epidemic in the US; 27,000 cases and 6,000 deaths were recorded, with 9,000 cases in New York City. At the time nobody knew how the virus was spreading. Many of the city's inhabitants, including scientists, thought that impoverished slum-dwelling immigrants were to blame even though the prevalence of the disease was higher in the more prosperous districts such as Staten Island – a pattern that had also been seen in  cities like Philadelphia. Many other industrialised countries were affected at the same time. In particular, before the outbreaks in the US, large epidemics had occurred in Sweden.
  The reason for the rise of polio in industrialised countries in the 20th century has never been fully explained. The disease is caused by a virus that is passed from person to person by the faecal-oral route, and naturally infects only humans. It is a paradox that it became a problem during times of improved sanitation and increasing affluence. Although the virus was discovered at the beginning of the 20th century, its ubiquity was unrecognised until the 1950s. It is now known that fewer than two per cent of individuals who are infected develop the disease, and most infections are mild. During epidemics the virus was effectively everywhere, which explains why public health officials were unable to isolate a source.
  Following the development of vaccines in the mid-1950s, mass vaccination campaigns took place in many countries. In the US, after a campaign promoted by the March of Dimes, the annual number of polio cases fell dramatically; the last outbreak was in 1979. In 1988 the World Health Organization along with others launched the Global Polio Eradication Initiative, and by 1994 the Americas were declared to be free of disease, followed by the Pacific region in 2000 and Europe in 2003. At the end of 2012, only 223 cases were reported by the World Health Organization. Mainly poliovirus type 1 infections, 122 occurred in Nigeria, one in Chad, 58 in Pakistan and 37 in Afghanistan. Vaccination teams often face danger; seven vaccinators were murdered in Pakistan and nine in Nigeria at the beginning of 2013. In Pakistan, the campaign was further hampered by the murder on 26 February 2013 of a police officer who was providing security.
caption: Hospital staff examining a patient in a tank respirator "iron lung", during the Rhode Island polio epidemic of 1960
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