Deterministic Chaos, El Niño Southern Oscillation, and Seasonal Influenza Epidemics

Abstract

Low precipitation enhances transmission of influenza viruses, which cause seasonal epidemics during the winter in northern and southern hemispheres. El Niño southern oscillation (ENSO) which modulates global precipitation is a multicomponent signal that is composed of sub-annual to multi-decadal oscillations. The dynamics of oscillatory components of ENSO and influenza are characterized, and causal relationship of annual oscillatory components is determined. Seasonality of influenza was determined in five geographical areas of north and south hemispheres. Monthly influenza time series of these regions and of ENSO were decomposed to oscillatory components. The oscillatory components were characterized in time-frequency and phase space domains. Periodicities of the oscillatory components of ENSO and influenza range from sub-annual to multidecadal. Time-dependent intrinsic correlations of instantaneous amplitude and frequencies of annual oscillatory components of ENSO and influenza are > 0.9. The dynamics of ENSO and influenza, which are dissipative with multifractal chaotic attractors, transit from quasi-periodic to chaotic regimes. Five most severe peaks of epidemic, which include 2009-2010 pandemic, occur during chaos. ENSO and influenza dynamics are phase coherent, but there is unidirectional causal effect of ENSO on influenza. Amplitude and frequency modulations of annual oscillatory components of ENSO and influenza are strongly coupled. Chaotic dynamics of ENSO determines the timing and severity of influenza epidemics. Monitoring of ENSO dynamics will aid public health surveillance of influenza epidemics.

Dynamic Regimes of El Niño Southern Oscillation and Influenza Pandemic Timing

“…Sea surface temperature (SST) of east Pacific Ocean ( 62 ) and southern oscillation index (SOI) ( 65 ) have been shown to be fractals. Multivariate ENSO data from 2000 to 2015 have, however, been shown to be multifractal ( 21 ). The time-varying Hurst exponents indicate that SOI and SST components are multifractals.…”

“…ENSO time series is composed of nonlinear components with timescales from sub-annual to multidecadal ( 20 , 21 ). The component of ENSO that modulates climate on annual timescale ( 22 ) is phase-locked to season cycles such as El Niño ( 23 ) which typically starts in spring and peaks in winter.…”

“…The component of ENSO that modulates climate on annual timescale ( 22 ) is phase-locked to season cycles such as El Niño ( 23 ) which typically starts in spring and peaks in winter. The dynamics of ENSO annual component has been shown to drive the dynamics of seasonal influenza ( 21 ), but while severe seasonal influenza epidemics and the 2009–2010 pandemic occurred during chaotic regime of ENSO dynamics, it is not known if this is true for all influenza pandemics. ENSO dynamics from 1876 to 2016 were characterized to determine if influenza pandemics are coupled to chaotic regimes.…”

Predicting COVID-19 Cases in South Korea Using Stringency and Niño Sea Surface Temperature Indices

“…In the paper of Oluwole (74), he emphasized that El Niño Southern Oscillation (ENSO) determines the timing and severity of influenza epidemics therefore influencing the seasonality of diseases. According to WHO (75) (https://www.who.int/ emergencies/diseases/novel-coronavirus-2019/question-andanswers-hub/coronavirus-disease-COVID-19-similaritiesand-differences-with-influenza), COVID-19 and influenza are respiratory diseases sharing many similar symptoms although the causative viruses and treatment may be different.…”