AUTHOR=Oluwole Olusegun Steven Ayodele TITLE=Dynamic Regimes of El Niño Southern Oscillation and Influenza Pandemic Timing JOURNAL=Frontiers in Public Health VOLUME=Volume 5 - 2017 YEAR=2017 URL=https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2017.00301 DOI=10.3389/fpubh.2017.00301 ISSN=2296-2565 ABSTRACT=El Niño southern oscillation (ENSO) dynamics has been shown to drive seasonal influenza dynamics. Severe seasonal influenza epidemics and the 2009–2010 pandemic were coincident with chaotic regime of ENSO dynamics. ENSO dynamics from 1876–2016 were charac- terized to determine if influenza pandemics are coupled to chaotic regimes. Time-varying spectra of southern oscillation index (SOI) and sea surface temperature (SST) were com- pared. SOI and SST were decomposed to components using the algorithm of noise assisted multivariate empirical mode decomposition. The components were Hilbert transformed to generate instantaneous amplitudes and phases. The trajectories and attractors of compo- nents were characterized in polar coordinates and state space. Influenza pandemics were mapped to dynamic regimes of SOI and SST joint recurrence of annual components . State space geometry of El Niños lagged by influenza pandemics were characterized and compared with other El Niños. Timescales of SOI and SST components ranged from sub-annual to multi-decadal. The trajectories of SOI and SST components and the joint recurrence of an- nual components were dissipative towards chaotic attractors. Periodic, quasi-periodic, and chaotic regimes were present in the recurrence of trajectories, but chaos-chaos transitions dominated. Influenza pandemics occurred during chaotic regimes of significantly low tran- sitivity dimension (p < 0.0001). El Niños lagged by influenza pandemics had distinct state space geometry (p < 0.0001). Chaotic dynamics explains the aperiodic timing, and varying duration and strength of El Niños. Coupling of all influenza pandemics of the past 140 years to chaotic regimes of low transitivity indicate that ENSO dynamics drives influenza pan- demic dynamics. Forecasts models from ENSO dynamics should compliment surveillance for novel influenza viruses.