Mortality and transmissibility patterns of the 1957 influenza pandemic in Maricopa County, Arizona

BMC Infectious Diseases

Research Article

Cécile Viboud¹  Megan Jehn²  Gerardo Chowell³  Clinton G. Nelson⁴  April J. Cobos⁵ 

[1] Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, MD, USA;School of Human Evolution and Social Change, Arizona State University, Tempe, AZ, USA;School of Human Evolution and Social Change, Arizona State University, Tempe, AZ, USA;Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, MD, USA;School of Public Health, Georgia State University, Atlanta, GA, USA;School of Human Evolution and Social Change, Arizona State University, Tempe, AZ, USA;School of Life Sciences, Arizona State University, Tempe, AZ, USA;School of Human Evolution and Social Change, Arizona State University, Tempe, AZ, USA;School of Life Sciences, Arizona State University, Tempe, AZ, USA;Barrett, the Honors College, Arizona State University, Tempe, AZ, USA;

关键词: 1957 influenza;    H2N2 virus;    Asian influenza;    Mathematical epidemiology;    Mortality rates;    Transmissibility;    Reproduction number;    Maricopa County;    Arizona;   

DOI  :  10.1186/s12879-016-1716-7

 received in 2016-03-02, accepted in 2016-07-13,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundWhile prior studies have quantified the mortality burden of the 1957 H2N2 influenza pandemic at broad geographic regions in the United States, little is known about the pandemic impact at a local level. Here we focus on analyzing the transmissibility and mortality burden of this pandemic in Arizona, a setting where the dry climate was promoted as reducing respiratory illness transmission yet tuberculosis prevalence was high.MethodsUsing archival death certificates from 1954 to 1961, we quantified the age-specific seasonal patterns, excess-mortality rates, and transmissibility patterns of the 1957 H2N2 pandemic in Maricopa County, Arizona. By applying cyclical Serfling linear regression models to weekly mortality rates, the excess-mortality rates due to respiratory and all-causes were estimated for each age group during the pandemic period. The reproduction number was quantified from weekly data using a simple growth rate method and assumed generation intervals of 3 and 4 days. Local newspaper articles published during 1957–1958 were also examined.ResultsExcess-mortality rates varied between waves, age groups, and causes of death, but overall remained low. From October 1959-June 1960, the most severe wave of the pandemic, the absolute excess-mortality rate based on respiratory deaths per 10,000 population was 16.59 in the elderly (≥65 years). All other age groups exhibit very low excess-mortality and the typical U-shaped age-pattern was absent. However, the standardized mortality ratio was greatest (4.06) among children and young adolescents (5–14 years) from October 1957-March 1958, based on mortality rates of respiratory deaths. Transmissibility was greatest during the same 1957–1958 period, when the mean reproduction number was estimated at 1.08–1.11, assuming 3- or 4-day generation intervals with exponential or fixed distributions.ConclusionsMaricopa County exhibited very low mortality impact associated with the 1957 influenza pandemic. Understanding the relatively low excess-mortality rates and transmissibility in Maricopa County during this historic pandemic may help public health officials prepare for and mitigate future outbreaks of influenza.

【 授权许可】

CC BY   
© The Author(s). 2016