Vulnerable Populations

All young adults were at highest risk of dying of influenza, but of these, two groups had especially high mortality rates: males and immigrants. The male mortality rate was fifty percent higher than the female rate, and the chances of death increased in foreign-born individuals. Some researchers have suggested that this is due to social and cultural behaviors. Young men were less likely to stay at home and rest when ill, allowing the disease to progress beyond the point of treatment. Usually, they also spent more time out of the home than women did, and daily contact with new microbes gave them stronger immune systems than females, increasing their chances of developing fatal cases of influenza or pneumonia. Immigrants were unfamiliar with American public health and healthcare systems and practices and did not seek care due to differing ethnic beliefs and language barriers.[1]

These cultural factors certainly played a role in male and immigrant susceptibility, but the biggest risk factors, especially for immigrants, were biological. Researchers surmise that previous influenza epidemics granted many individuals some immunity to the 1918-1919 virus. However, these epidemics primarily affected urban areas. The immigrant rush of the early twentieth century brought thousands of men and women between the ages of 20 and 40 to the United States, most from rural areas of Eastern and Southern Europe. Their lack of exposure to disease, especially compared to their American neighbors in crowded workplaces and urban tenements, made them especially susceptible to influenza in 1918.[2]

Influenza killed with no regard for physical strength, gender, race, or ethnicity, and indigenous peoples around the world, however isolated, suffered exceptionally high morbidity and mortality rates during the pandemic. The relative isolation of many indigenous peoples meant they had little or no natural immunity to pathogens of any kind and little or no access to public health and healthcare resources. The lethal virus of 1918-1919 killed entire villages in the remote corners of Alaska and decimated populations in the Pacific islands. In the United States, the Native American mortality rate was four times that of urban whites. Influenza infected twenty-four percent of those on reservations and the virus killed two percent of the entire Native population between October 1918 and March 1919. The experience of Native populations is an extremely important part of the pandemic narrative, especially for Montana, a state with seven reservations. High mortality rates on reservations may mean that Montana’s overall mortality rate is much higher than originally believed. However, much more study is necessary to understand the impact of influenza on Montana’s reservations and tribal populations.[3]


[1] Thomas A. Garret, “War and Pestilence as Labor Market Shocks: U.S. Manufacturing Wage Growth, 1914-1919.” Economic Inquiry 47 no. 4 (October 2009), 713; Howard Phillips and David Killingray, introduction to The Spanish Influenza Pandemic of 1918-1919: New Perspectives (London: Routledge, 2003), 8; Crosby, America’s Forgotten Pandemic, 67.

[2] Walters, “The Contemporary Perspective,” 857; Katz, “A Study in Mortality,” 422; Katz, “Further Study in Mortality,” 619.

[3] Crosy, America’s Forgotten Pandemic, 231-2; Steele, “Montana Frontier,” 83.

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The “Most Peculiar Disease”

The number of cases and deaths do not fully illustrate the horror of the pandemic; it is important to understand the virus itself, its symptoms, and the reason why it was such an effective killer. The disease often struck suddenly. A hospital administrator in Glasgow, Montana reported that this influenza was “the most peculiar disease [she had]…ever seen. Some persons hardly know they are sick until they’re dying.”[1] John H. Walters, M.D., discusses the illness’s symptoms, which included fatigue, body aches and pain, cough, and fevers of up to 104°F. Most horrifying, though, was cyanosis, a bluish discoloration of the face and extremities caused by a lack of oxygen. Many historians and scientists describe cyanosis as a sure sign that death was imminent, especially when moist, productive coughing and hemorrhaging accompanied it.[2] 

Almost all pandemic scholars comment on its unique W-shaped mortality curve. In most influenza outbreaks, including seasonal influenza, mortality curves are U-shaped, with most deaths occurring among the very young and very old. The 1918-1919 influenza, however, struck down young, otherwise healthy adults most often. Ironically, researchers blame the very strong immune response of these individuals as the reason. John M. Barry and Tom Quinn provide excellent and understandable descriptions of a phenomenon termed “cytokine storm.” Strong immune systems mounted a response that released large quantities of immune proteins. The sheer volume of these proteins, though, damaged delicate lung tissue. Unable to function properly, lung cells broke down, and blood, fluids, and other wastes filled the lungs. Influenza and pneumonia victims literally drowned.[3]

The cause of the pandemic of 1918-1919 was a mystery until 1997 when a team of scientists at the Armed Forces Institute of Pathology isolated its gene sequence in the tissues of victims frozen in Alaska’s permafrost. This groundbreaking discovery allowed subsequent research projects to determine that 1918-1919’s strain of influenza was H1N1 swine influenza, not the avian variation that many believed it had been. These findings allowed for the development of a vaccine that may help to prevent future pandemics caused by the 1918-1919 strain.[4]


[1] Mullen and Nelson, “Montanans and the ‘Most Peculiar Disease,’” 59.

[2] John H. Walters, M.D., “Influenza 1918: The Contemporary Perspective,” Bulletin of the New York Academy of Medicine 54 no. 9 (October 1978): 855-64.

[3] John M. Barry, The Great Influenza: The Epic Story of the Deadliest Plague in History, rev. ed., New York: Penguin Books, 2009; Tom Quinn, Flu: A Social History of Influenza, London: New Holland Publishers, 2008.

[4] Jeffery K. Taubenberger, et. al., “Initial Genetic Characterization of the 1918 ‘Spanish’ Influenza Virus,” Science 275 no. 5307 (March 21, 1997): 1793-6.

Introduction to the 1918-1919 Influenza Pandemic in Montana

In the spring of 1918, a deadly strain of influenza began circling the globe. Within a year the virus killed between 30 and 50 million people worldwide and approximately 675,000 in the United States. The pandemic significantly affected even rural, sparsely populated areas. Approximately 5,000 Montanans died of influenza between August 1918 and June 1919, about one percent of the state’s population, and public health officials estimated that this number was, most likely, at the low end of the spectrum.[1] Montana suffered one of the four highest mortality rates of all states; only Pennsylvania, Maryland, and Colorado recorded more influenza deaths per capita during the pandemic. The obvious geographic and cultural differences between these states raise the question as to why Montana suffered such a high mortality rate. Specifically, how did the state’s unique demographic, social, and cultural factors influence its pandemic experience?

Pandemic historian Alfred Crosby notes that “the states with the highest excess mortality rates…had little indeed in common economically or demographically, climatically or geographically.”[2] However, individually, factors such as these significantly influenced mortality rates in each area. In Montana, demographics, economics, social beliefs and customs, and even climate were to blame for the state’s high mortality rate. The influenza virus of 1918-1919 was unique in that it showed a preference for young, healthy adults, especially males and immigrants. These demographic groups made up the majority of early twentieth-century Montana population, making the state especially susceptible. The economic pursuits that brought these individuals to Montana created an environment that made it difficult for them to prevent and treat influenza once it arrived. Rural agricultural communities often did not have medical providers nearby, and the living and working conditions in the state’s population centers sometimes jeopardized residents’ health, making them more susceptible to influenza. Public health officials instituted policies and measures to prevent the spread of the disease, but some independent-minded Montanans defied the orders, often to their own detriment. However, Montana’s dry climate presented public health officials with a unique challenge that, at the time, they did not realize. The virus’s ability to survive longer in low humidity made the dry years of 1918 and 1919 in Montana an ideal place for influenza to thrive.


[1] Pierce C. Mullen and Michael L. Nelson, “Montanans and ‘The Most Peculiar Disease’: The Influenza Epidemic and Public Health, 1918-1919,” Montana: The Magazine of Western History 37 no. 2 (Spring 1987), 51. Public health officials did not require physicians to report cases of influenza until well into the pandemic. Furthermore, public health officials presumed that many cases of influenza went unreported even after it was a requirement, as overworked medical providers simply did not have time to record all their patient visits.
[2] Alfred W. Crosby, America’s Forgotten Pandemic: The Influenza of 1918, 2nd ed. (New York: Cambridge University Press, 1989), 66.