The 1918–1920 influenza pandemic in Peru

Abstract

Background Increasing our knowledge of past influenza pandemic patterns in different regions of the world is crucial to guide preparedness plans against future influenza pandemics. Here, we undertook extensive archival collection efforts from 3 representative cities of Peru (Lima in the central coast, Iquitos in the northeastern Amazon region, Ica in the southern coast) to characterize the age and geographic patterns of the 1918–1920 influenza pandemic in this country. Materials and Methods We analyzed historical documents describing the 1918–1920 influenza pandemic in Peru and retrieved individual mortality records from local provincial archives for quantitative analysis. We applied seasonal excess mortality models to daily and monthly respiratory mortality rates for 1917–1920 and quantified transmissibility estimates based on the daily growth rate in respiratory deaths. Results A total of 52,739 individual mortality records were inspected from local provincial archives. We found evidence for an initial mild pandemic wave during July-September 1918 in Lima, identified a synchronized severe pandemic wave of respiratory mortality in all three locations in Peru during November 1918-February 1919, and a severe pandemic wave during January 1920- March 1920 in Lima and July-October 1920 in Ica. There was no recrudescent pandemic wave in 1920 in Iquitos. Remarkably, Lima experienced the brunt of the 1918–20 excess mortality impact during the 1920 recrudescent wave, with all age groups experiencing an increase in all cause excess mortality from 1918–19 to 1920. Middle age groups experienced the highest excess mortality impact, relative to baseline levels, in the 1918–19 and 1920 pandemic waves. Cumulative excess mortality rates for the 1918–20 pandemic period were higher in Iquitos (2.9%) than Lima (1.6%). The mean reproduction number for Lima was estimated in the range 1.3–1.5. Conclusions We identified synchronized pandemic waves of intense excess respiratory mortality during November 1918-February 1919 in Lima, Iquitos, Ica, followed by asynchronous recrudescent waves in 1920. Cumulative data from quantitative studies of the 1918 influenza pandemic in Latin American settings have confirmed the high mortality impact associated with this pandemic. Further historical studies in lesser-studied regions of Latin America, Africa, and Asia are warranted for a full understanding of the global impact of the 1918 pandemic virus.

Death Patterns during the 1918 Influenza Pandemic in Chile

“…Pandemic-related excess mortality rates for 1918–1921 varied 10-fold across the 24 provinces; these differences were partly explained by latitude, baseline mortality rates, and population density. In agreement with previous reports ( 4 – 7 , 9 – 12 ), we found that among all age groups, the RR for pandemic death was highest among young adults 20–29 years of age. Our findings also indicate substantial excess mortality rates for senior populations, in agreement with previous reports from central Mexico ( 6 ) and Colombia ( 7 ).…”

“…A consistent finding across reports from North America, Europe, Latin America, and Asia ( 4 – 7 , 9 – 12 ) is the disproportionate increase in mortality rates among young adults during the pandemic period compared with prepandemic years. Further reports from the United States and Europe have shown that influenza-related deaths among seniors ( > 50 years of age) were significantly reduced during the lethal 1918–19 pandemic wave relative to baseline periods.…”

“…Our understanding of the epidemiologic patterns of this pandemic has improved over the past decade as a result of intensive efforts to locate, digitize, and analyze archival disease records ( 3 ). In particular, studies focusing on the United States ( 4 , 5 ), Mexico ( 6 ), Colombia ( 7 ), Brazil ( 8 ), and Peru ( 9 ) have shed light on geographic variation in the patterns of timing, intensity, and patient age during successive pandemic waves across the Americas. Yet there have been no reports from temperate locales of South America; this gap prevents a complete understanding of the epidemiology of the pandemic throughout the continent and across different climatic zones.…”

Preparing for Pandemic Influenza: The Global 1918 Influenza Pandemic and the Role of World Historical Information

“…While Patterson and Pyle have attempted to describe the pandemic across the globe, their focus is on European and North American data, recognizing three waves during the period of spring 1918 to spring 1919. They do not mention, for example, that Peru experienced an additional deadly wave in 1920 (Chowell, et al 2011). In other words, there has been no comprehensive characterization of the pandemic globally in terms of numbers of waves, their relative severity, and their speed.…”

Pandemic influenza and socioeconomic disparities: Lessons from 1918 Chicago

“…In 2006, a seminal study revealed more than 30-fold variation in 1918 pandemic excess mortality rates across a sample of 20 countries, with socioeconomic factors explaining a significant fraction of the observed variation (2). In Latin America, pandemic excess mortality rates varied from 0.4 to 2.9% in national and province-level data, a greater than sevenfold variation (4,8,9). In contrast, United States and European populations fared relatively well during the pandemic, despite intense disruption at the end of World War I (excess mortality rates of 0.5-1.1%) (3,5).…”