Temporal scaling behavior of avian influenza a (H5N1): The multifractal detrended fluctuation analysis

Abstract

The highly pathogenic avian influenza A H5N1 has become a serious public health problem, fatal to poultry and humans all over the world. Since its detection in 2003, H5N1 viruses have exhibited considerable capability of transmission from wild birds to humans, spreading from southeastern Asia across Europe and into Africa. Avian influenza has been recognized as a potential pandemic by practitioners and scientists and has become an important research issue in virology, molecular biology, phylogeography, and spatial epidemiology. Although avian influenza has explicit spatial and temporal dimensions, rigorous geographical analysis, particular its temporal process, of the outbreaks is at its initial stage. The purpose of this article is to provide an approach to study the temporal behaviors of avian influenza A (H5N1) over multiple time scales by analyzing the global and continental outbreak time series from December 2003 to March 2009. The detection of long-range correlation and multifractality in the outbreak series provide answers to the following questions: (1) whether previous H5N1 outbreaks are responsible for and have long-term effects on current infections; (2) whether H5N1 outbreaks have special temporal patterns manifested by multiscaling behaviors; and (3) whether H5N1 outbreaks over time are heterogeneous in different parts of the world. Multifractal detrended fluctuation analysis is employed in this study to detect long-range correlation and multifractal scaling behaviors of the H5N1 outbreaks. Experimental results show that H5N1 outbreaks are long-range correlated and multifractal. The temporal patterns are heterogeneous over space. This implies that H5N1 outbreaks behave differently under different ecosystems, poultry farm practices, and public health measures. © 2011 by Association of American Geographers.