Pandemic of 1918

Article By:

Pierce, Marcia M. Department of Biological Sciences, Eastern Kentucky University, Richmond, Kentucky.

Last reviewed:2009

DOI:https://doi.org/10.1036/1097-8542.YB090071

The Spanish influenza pandemic of 1918–1919 is considered the most devastating outbreak of infectious disease in recorded history. In fact, the Spanish flu killed more people in a period of 25 weeks than acquired immune deficiency syndrome (AIDS) has killed in 25 years. Conservative estimates place the number of fatalities at 20 million; others believe that the number may be as many as 50 million within a very short time frame. This pandemic is sometimes called the “forgotten” pandemic because of the way it has passed out of the collective consciousness. The pandemic was caused by an unusually severe and virulent strain of the influenza A virus subtype H1N1. Recently, scientists bioengineered genes from the original chromosome of the 1918 influenza virus into template influenza viruses that had very limited capability of causing disease. Genes for two of the major proteins in influenza virus were used: hemagglutinin (HA) and neuraminidase (NA). It was found that the HA protein made these viruses highly lethal in mice, which previously had not developed disease after being infected with the template virus. Further studies in macaques found that much of the damage results from the host's immune response, which causes a “cytokine storm” in the patient. These results suggest that the primary reason for the pandemic's severity was the virulent proteins of the virus and not the conditions of the era in which it occurred.

The content above is only an excerpt.