Network for Biological Invasions and Dispersal Research

MITACS Seminar at the University of New Brunswick, Fredericton

Tuesday, 16 March, 2010,

Daihai He

McMaster University

will speak on

Likelihood-based inference on the cause of multiple waves in the 1918 influenza pandemic in London

TBA

Abstract: Multiple waves have been observed in the initial phase of influenza pandemics, notably the 1918 pandemic. The mechanisms that account for this phenomenon remain unclear. We used mathematical modeling and likelihood-based inference to shed light on this issue. We started with the simplest, three-compartment model including susceptible(S), infectious(I) and immunized(R) states, and allowing immunity to decay. We focused on the Pneumonia and Influenza (P&I) mortality in London, England, during 1918 influenza pandemic. We employed the R package POMP (statistical inference for partially observed Markov processes) to find the parameter values with maximum likelihood. We considered two time-dependent factors that might lead to multiple waves: (i) changes in the transmission rate and (ii) changes in the rate of decay of immunity. We found that either these factors can lead to good fits to the 1918 P&I mortality in London, but that the second-order Akaike's Information Criterion (AICc) favours changes in the transmission rate.

Joint work with David Earn, Troy Day, Jonathan Dushoff and Junling Ma.