The Influenza Syndemics
There were three influenza pandemics during the 20th century that caused widespread illness, mortality, social disruption, and significant economic losses. These occurred in 1918, 1957, and 1968. In each case, mortality rates were determined primarily by five factors: the number of people who became infected, the virulence of the virus causing the pandemic, the speed of global spread, the underlying features and vulnerabilities of the most affected populations, and the effectiveness and timeliness of the prevention and treatment measures that were implemented. These factors unite a range of bio-social causal forces, including production, communication, and transportation technologies; the medical and public health infrastructures; the specific pathogens involved and the nature of their interactions with human hosts; and the pre-existing health status of patients. All of these, in turn, are shaped, to greater or somewhat lesser degree, by overarching political economic structures globally and locally. Epidemics, in short, including their emergence, course, and impact (and whether they become widespread pandemics that exact a sorrowful toll on life and well-being) are sculpted by the configuration of human social relationships including prevailing patterns of social inequality.
The 1957 pandemic was caused by the Asian influenza virus (known as the H2N2 strain), a novel influenza variety to which humans had not yet developed immunities. The death toll of the 1957 pandemic is estimated to have been around two million globally, with approximately 70,000 deaths in the United States. A little over a decade later, the comparatively mild Hong Kong influenza pandemic erupted due to the spread of a virus strain (H3N2) that genetically was related to the more deadly form seen in 1957. The pandemic was responsible for about one million deaths around the world, almost 34,000 of which were in the United States. In both of these pandemics, death may not have been due only to the primary viral infection, but also to secondary bacterial infections among influenza patients; in short, they were caused by a viral/bacterial syndemic (but see Chatterjee 2007).
The worst of the 20th century influenza pandemics was the 1918 outbreak, which epidemiologists estimate was responsible for the deaths of between 40-100 million people worldwide, making it one of the most deadly events in human history. More people died of the so-called Spanish flu (caused by the H1N1 viral strain) pandemic in the single year of 1918 than during all four-years of the Black Death (Bubonic plague) scourge that lasted from 1347 to 1351 (although a significantly higher percentage of the world’s population died of the plague than of Spanish flu). It is estimated that between 20-40 percent of the world’s population became ill during the 1918 pandemic.
The pandemic had devastating effects as disease spread along trade and shipping routes and other corridors of human movement until it had circled the globe. In places like India, the mortality rate reached 50 per 1,000 population. Arriving during the closing phase of the World War I, the pandemic had a significant impact on mobilized national armies. Half of U.S. soldiers who died in the "Great War," for example, were victims of influenza not of enemy bombs and bullets. It is estimated that almost ¾ of a million Americans died during the pandemic. As noted by one alarmed scientific observer at the time, " civilization could easily disappear from the face of the earth within a matter of a few more weeks". In part, the death toll during the pandemic was caused by viral pneumonia characterized by extensive bleeding in the lungs resulting in suffocation. Many victims died within 48 hours of the appearance of the first symptom. In fact, it was not uncommon for people who appeared to be quite healthy in the morning to have died by sunset. Among those who survived the first several days, however, many died of secondary bacterial pneumonia. Moreover, it has been argued that countless numbers of those who expired quickly from the disease were co-infected with tuberculosis, which would explain the notable plummet in TB cases after 1918 (because so many carriers of the disease perished during the influenza pandemic). Again, as seen with the previous two 20th century global influenza outbreaks, disease interaction appears to have been critical, underlining the importance of syndemics more generally in the production of major public health crises.
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