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Facts About the Spanish Flu

The Spanish Flu is one of several types of influenza viruses, which are contagious illnesses with symptoms that range from mild to severe and can cause death. The Spanish Flu is a killer virus. In 1918, it killed between 20 million and 40 million people, including, it is thought, about 40 percent of American World War I soldiers, according to the National Institute of Allergy and Infectious Diseases. Other estimates place the number of deaths in the 40 million to 100 million range.

  1. Affected Areas

    • The 1918 Spanish Flu was a pandemic--a global outbreak---that not only swept through Europe and North America, but also found its way to remote places like isolated islands in the Pacific. About 500 million people were infected. Between 25 and 30 percent of people worldwide suffered from acute illness. Of those infected, more than 2.5 percent died. Mortality during flu epidemics is usually 0.1 percent. The virus seems to have originated in the United States, but cases popped up so quickly in Europe and Asia, as well, that the geographical origin of the Spanish Flu is not an absolute certainty.

    When the Spanish Flu Struck

    • The first wave of the Spanish Flu appears to have begun in March of 1918 and struck people throughout North America, Europe and Asia. The second wave swept through the world during the months of September through November of 1918, and this second wave of the virus was much more virulent. In the beginning of 1919, a third lethal wave struck many places. The ability of the Spanish Flu to strike over and over again within the space of a year is unusual.

    Strain

    • There are three types of influenza viruses: A, B and C. Type A is the most dangerous, and it in this category that Spanish Flu belongs. Type A viruses are further divided into subgroups according to the surface proteins HA and NA. The Spanish Flu is an H1N1 subtype. The genome of the 1918 Spanish Flu is related to avian flu virus and is the ancestor of human and classical swine H1N1 viruses, according to research led by Jeffery K. Taubenberger, a tenured investigator with the Laboratory of Infectious Diseases at the National Institute of Allergy and Infectious Diseases. Thus, it appears the Spanish Flu is a mutated bird flu that jumped directly to humans, who then infected pigs. As a new human virus it met little resistance and spread easily from person to person.

    Unusual Features

    • The reason behind the 1918 flu's unusual ability to produce waves of illness within a year is still unknown. The virulence of the virus is also an unusual feature. In October 1918, almost 11,000 people died in Philadelphia alone. In six months the Spanish Flu killed 675,000 in the U.S. By comparison, death from seasonal flu in the U.S. is about 36,000 annually. The Spanish Flu chose unusual victims. Usually, influenza viruses are more threatening to the very young or old. This influenza strain, though, was most lethal to healthy adults, causing death rates from flu and pneumonia in those ages 15 to 34 to skyrocket to more than twenty times what they were before 1918.

    How the Spanish Flu Killed

    • Most people dying as a result of contracting the virus fell to bacterial pneumonia in an age when antibiotics were not available. Yet, there was another group of people who died quickly, sometimes within hours of the first symptoms, suffocating in blood and sputum produced by pulmonary hemorrhage or edema. The virus replicated itself rapidly within the respiratory system.

    Flu in Swine

    • Pigs didn't have influenza virus before 1918. It was in the fall of that year that flu in pigs was discovered during the second wave of the Spanish Flu's spread in humans. The flu spread throughout swine herds in the Midwest, where the first human case of Spanish Flu is thought to have developed. Severe cases were discovered then in Europe and China, too. The next year in the U.S, the epizootic--animal epidemic--was as severe as the year before. The flu has reappeared in swine herds every year since then, including in Europe and Asia. While avian flu does not commonly jump from wild birds directly to humans, this isn't the case with pigs. Since pigs can catch flu from both birds and humans, combined flu strains such as the 2009 H1N1 flu are of concern.

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