page_title: Spanish flu
section_title: Research
hierarchical_section_title: Spanish flu / Research
caption_attribution_description: English: This 2005 photograph of the Centers for Disease Control and Prevention’s Dr. Terrence Tumpey, one of the organization’s staff microbiologists and a member of the National Center for Infectious Diseases (NCID), showed him examining reconstructed 1918 Pandemic Influenza Virus inside a specimen vial containing an orange-colored supernatant culture medium. Dr. Tumpey, here seen in a Biosafety Level 3-enhanced laboratory setting, was working beneath a flow hood, which pulls air from outside the hood into the hood’s confines, and is then filtered of any pathogens before being re-circulated inside the self contained laboratory atmosphere. Dr. Tumpey recreated the 1918 influenza virus in order to identify the characteristics that made this organism such a deadly pathogen. Research efforts such as this, enables researchers to develop new vaccines and treatments for future pandemic influenza viruses. The 1918 Spanish flu epidemic was caused by an influenza A (H1N1) virus, killing more than 500,000 people in the United States, and up to 50 million worldwide. The possible source was a newly emerged virus from a swine or an avian host of a mutated H1N1 virus. Many people died within the first few days after infection, and others died of complications later. Nearly half of those who died were young, healthy adults. Influenza A (H1N1) viruses still circulate today after being introduced again into the human population in the 1970s. Italiano: Maschera a pieno facciale e guanti in lattice. Scienziati del centro di ricerca CDC che lavorano sull'influenza in condizioni di bio sicurezza. Português: Máscara facial com insuflamento de ar. Cientista realizando pesquisa sobre o vírus influenza em altas condições de segurança biológica.
context_page_description: The Spanish flu, also known as the 1918 flu pandemic, was an unusually deadly influenza pandemic caused by the H1N1 influenza A virus. Lasting from February 1918 to April 1920, it infected 500 million people–about a third of the world's population at the time–in four successive waves. The death toll is typically estimated to have been somewhere between 17 million and 50 million, making it one of the deadliest pandemics in human history.
  The first observations of illness and mortality were documented in the United States, France, Germany and the United Kingdom. To maintain morale, World War I censors minimized these early reports. Newspapers were free to report the epidemic's effects in neutral Spain, such as the grave illness of King Alfonso XIII, and these stories created a false impression of Spain as especially hard hit. This gave rise to the name "Spanish" flu. Historical and epidemiological data are inadequate to identify with certainty the pandemic's geographic origin, with varying views as to its location.
context_section_description: The origin of the Spanish flu pandemic, and the relationship between the near-simultaneous outbreaks in humans and swine, have been controversial. One hypothesis is that the virus strain originated at Fort Riley, Kansas, in viruses in poultry and swine which the fort bred for food; the soldiers were then sent from Fort Riley around the world, where they spread the disease. Similarities between a reconstruction of the virus and avian viruses, combined with the human pandemic preceding the first reports of influenza in swine, led researchers to conclude the influenza virus jumped directly from birds to humans, and swine caught the disease from humans.
  
  Others have disagreed, and more recent research has suggested the strain may have originated in a nonhuman, mammalian species. An estimated date for its appearance in mammalian hosts has been put at the period 1882–1913. This ancestor virus diverged about 1913–1915 into two clades (or biological groups), which gave rise to the classical swine and human H1N1 influenza lineages. The last common ancestor of human strains dates to between February 1917 and April 1918. Because pigs are more readily infected with avian influenza viruses than are humans, they were suggested as the original recipients of the virus, passing the virus to humans sometime between 1913 and 1918.
  An effort to recreate the 1918 flu strain (a subtype of avian strain H1N1) was a collaboration among the Armed Forces Institute of Pathology, the USDA ARS Southeast Poultry Research Laboratory, and Mount Sinai School of Medicine in New York City. The effort resulted in the announcement (on 5 October 2005) that the group had successfully determined the virus's genetic sequence, using historic tissue samples recovered by pathologist Johan Hultin from an Inuit female flu victim buried in the Alaskan permafrost and samples preserved from American soldiers  Roscoe Vaughan and James Downs.
  On 18 January 2007, Kobasa et al. (2007) reported that monkeys (Macaca fascicularis) infected with the recreated flu strain exhibited classic symptoms of the 1918 pandemic, and died from cytokine storms – an overreaction of the immune system. This may explain why the 1918 flu had its surprising effect on younger, healthier people, as a person with a stronger immune system would potentially have a stronger overreaction.
  On 16 September 2008, the body of British politician and diplomat Sir Mark Sykes was exhumed to study the RNA of the flu virus in efforts to understand the genetic structure of modern H5N1 bird flu. Sykes had been buried in 1919 in a lead coffin which scientists hoped had helped preserve the virus. The coffin was found to be split and the cadaver badly decomposed; nonetheless, samples of lung and brain tissue were taken.
  In December 2008, research by Yoshihiro Kawaoka of the University of Wisconsin linked the presence of three specific genes (termed PA, PB1, and PB2) and a nucleoprotein derived from 1918 flu samples to the ability of the flu virus to invade the lungs and cause pneumonia. The combination triggered similar symptoms in animal testing.
  In June 2010, a team at the Mount Sinai School of Medicine reported the 2009 flu pandemic vaccine provided some cross-protection against the 1918 flu pandemic strain.
  One of the few things known for certain about influenza in 1918 and for some years after was that it was, except in the laboratory, exclusively a disease of human beings.
  In 2013, the AIR Worldwide Research and Modeling Group "characterized the historic 1918 pandemic and estimated the effects of a similar pandemic occurring today using the AIR Pandemic Flu Model". In the model, "a modern-day 'Spanish flu' event would result in additional life insurance losses of between US$15.3–27.8 billion in the United States alone", with 188,000–337,000 deaths in the United States.
  In 2018, Michael Worobey, an evolutionary biology professor at the University of Arizona who is examining the history of the 1918 pandemic, revealed that he obtained tissue slides created by William Rolland, a physician who reported on a respirato
caption: At the Centers for Disease Control and Prevention, Terrence Tumpey examines a reconstructed version of the 1918 flu.
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