Giuseppe
Emeritus
[Source: PLoS ONE, full text: (LINK). Abstract, edited.]
Influenza and Pneumonia Mortality in 66 Large Cities in the United States in Years Surrounding the 1918 Pandemic
Rodolfo Acuna-Soto<SUP>1</SUP><SUP>*</SUP>, C?cile Viboud<SUP>2</SUP>, Gerardo Chowell<SUP>2</SUP><SUP>,</SUP><SUP>3</SUP>
1 Departamento de Microbiologia y Parasitologia, Facultad de Medicina, Universidad Nacional Aut?noma de M?xico, M?xico City, M?xico, 2 Division of Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America, 3 School of Human Evolution and Social Change, Mathematical, Computational & Modeling Sciences Center, Arizona State University, Tempe, Arizona, United States of America
Abstract
The 1918 influenza pandemic was a major epidemiological event of the twentieth century resulting in at least twenty million deaths worldwide; however, despite its historical, epidemiological, and biological relevance, it remains poorly understood. Here we examine the relationship between annual pneumonia and influenza death rates in the pre-pandemic (1910?17) and pandemic (1918?20) periods and the scaling of mortality with latitude, longitude and population size, using data from 66 large cities of the United States. The mean pre-pandemic pneumonia death rates were highly associated with pneumonia death rates during the pandemic period (Spearman ρ = 0.64?0.72; P<0.001). By contrast, there was a weak correlation between pre-pandemic and pandemic influenza mortality rates. Pneumonia mortality rates partially explained influenza mortality rates in 1918 (ρ = 0.34, P = 0.005) but not during any other year. Pneumonia death counts followed a linear relationship with population size in all study years, suggesting that pneumonia death rates were homogeneous across the range of population sizes studied. By contrast, influenza death counts followed a power law relationship with a scaling exponent of ~0.81 (95%CI: 0.71, 0.91) in 1918, suggesting that smaller cities experienced worst outcomes during the pandemic. A linear relationship was observed for all other years. Our study suggests that mortality associated with the 1918?20 influenza pandemic was in part predetermined by pre-pandemic pneumonia death rates in 66 large US cities, perhaps through the impact of the physical and social structure of each city. Smaller cities suffered a disproportionately high per capita influenza mortality burden than larger ones in 1918, while city size did not affect pneumonia mortality rates in the pre-pandemic and pandemic periods.
Citation: Acuna-Soto R, Viboud C, Chowell G (2011) Influenza and Pneumonia Mortality in 66 Large Cities in the United States in Years Surrounding the 1918 Pandemic. PLoS ONE 6(8): e23467. doi:10.1371/journal.pone.0023467
Editor: Benjamin J. Cowling, University of Hong Kong, Hong Kong
Received: February 7, 2011; Accepted: July 18, 2011; Published: August 19, 2011
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Funding: These authors have no support or funding to report.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: acunasoto.rodolfo@gmail.com
- -------Rodolfo Acuna-Soto<SUP>1</SUP><SUP>*</SUP>, C?cile Viboud<SUP>2</SUP>, Gerardo Chowell<SUP>2</SUP><SUP>,</SUP><SUP>3</SUP>
1 Departamento de Microbiologia y Parasitologia, Facultad de Medicina, Universidad Nacional Aut?noma de M?xico, M?xico City, M?xico, 2 Division of Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America, 3 School of Human Evolution and Social Change, Mathematical, Computational & Modeling Sciences Center, Arizona State University, Tempe, Arizona, United States of America
Abstract
The 1918 influenza pandemic was a major epidemiological event of the twentieth century resulting in at least twenty million deaths worldwide; however, despite its historical, epidemiological, and biological relevance, it remains poorly understood. Here we examine the relationship between annual pneumonia and influenza death rates in the pre-pandemic (1910?17) and pandemic (1918?20) periods and the scaling of mortality with latitude, longitude and population size, using data from 66 large cities of the United States. The mean pre-pandemic pneumonia death rates were highly associated with pneumonia death rates during the pandemic period (Spearman ρ = 0.64?0.72; P<0.001). By contrast, there was a weak correlation between pre-pandemic and pandemic influenza mortality rates. Pneumonia mortality rates partially explained influenza mortality rates in 1918 (ρ = 0.34, P = 0.005) but not during any other year. Pneumonia death counts followed a linear relationship with population size in all study years, suggesting that pneumonia death rates were homogeneous across the range of population sizes studied. By contrast, influenza death counts followed a power law relationship with a scaling exponent of ~0.81 (95%CI: 0.71, 0.91) in 1918, suggesting that smaller cities experienced worst outcomes during the pandemic. A linear relationship was observed for all other years. Our study suggests that mortality associated with the 1918?20 influenza pandemic was in part predetermined by pre-pandemic pneumonia death rates in 66 large US cities, perhaps through the impact of the physical and social structure of each city. Smaller cities suffered a disproportionately high per capita influenza mortality burden than larger ones in 1918, while city size did not affect pneumonia mortality rates in the pre-pandemic and pandemic periods.
Citation: Acuna-Soto R, Viboud C, Chowell G (2011) Influenza and Pneumonia Mortality in 66 Large Cities in the United States in Years Surrounding the 1918 Pandemic. PLoS ONE 6(8): e23467. doi:10.1371/journal.pone.0023467
Editor: Benjamin J. Cowling, University of Hong Kong, Hong Kong
Received: February 7, 2011; Accepted: July 18, 2011; Published: August 19, 2011
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Funding: These authors have no support or funding to report.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: acunasoto.rodolfo@gmail.com