![]() ![]() The 1830–1833 pandemic, though less impressive, arrived at about the same time as the second cholera pandemic (1831–1833), of which the inevitable march toward Europe was followed for over a year in the daily newspapers, helping to establish a deep popular epidemiological concept of pandemic diseases. ![]() The 1789–1799 pandemic, coming soon thereafter, emphasized this recently learned lesson. The 1781–1782 pandemic evolved so rapidly, and was so widespread, that explosive outbreaks of febrile respiratory illness in the general population alone became a distinguishing characteristic, supporting the notion of a specific disease entity. In the pre-microbial era, influenza had been considered among the more confusing of the pandemic diseases for several reasons: (i) the signs and symptoms were non-specific, leading to confusion with other conditions (ii) interpandemic influenza-like illnesses were often attributed to other upper respiratory infections (URIs), fuelling ongoing debates about whether interpandemic influenza existed at all, or whether URIs were the same thing as interpandemic influenza (iii) pandemics occurred sporadically and unpredictably, prompting debates about whether a new influenza-like disease was the same as the one seen decades ago and (iv) mortality statistics, which began to appear in developed nations in the mid-1800s, showed high mortality only for the first year or two of a pandemic, seeming to support the belief that interpandemic influenza did not occur.Įach of four major influenza pandemics before 1918, however, incrementally advanced scientific understanding of the disease. Epidemiological notions of carriers and intermediate vectors were not easily envisioned, preventing many observers from accepting a unified concept of infectious diseases, some of which were directly transmissible from person to person (for example, smallpox), others of which were acquired from intermediate vector hosts (for example, plague), still others of which were acquired from contaminated environmental sources (for example, cholera) or were acquired by more than one of the mechanisms just noted (for example, smallpox and cholera). ![]() In the pre-microbiological era (before 1876) there was much confusion about the causes of both the common communicable diseases like colds, smallpox, and measles, and the great epidemic diseases like cholera and plague. In describing here the 10-year effort (1995–2005) to sequence the genome of the 1918 pandemic influenza virus, we attempt also to place it within this important historical perspective.įraming influenza as a clinical and epidemiological entity Along the way, the new fields of bacteriology and virology were advanced, and a productive marriage between microbiology, epidemiology and experimental science began. Indeed, the influenza search not only pre-dated the great pandemic of 1918, but also attracted the efforts of some of the greatest researchers of the 19th and 20th centuries. However, in reviewing the scientific approach to unlocking an old puzzle, it is important to note that the sequencing of the 1918 virus took place after more than century of exhaustive and sometimes disheartening efforts to discover the cause of influenza ( Figure 1). The ongoing H5N1 avian influenza epizootic, and the possibility that it might also cause a pandemic, increase the importance of understanding what happened in 1918. The announcement in 2005 that a virus causing fatal influenza during the great influenza pandemic of 1918–1919 had been sequenced in its entirety, in the laboratory of co-author JKT, has prompted renewed interest in the 1918 virus. ![]()
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