Molecular Epidemiology of Seasonal & Pandemic Influenza A (H1N1) in Hawai‘i

Influenza is a viral infection causing seasonal outbreaks, periodic epidemics and global pandemics in humans, the latest being the 2009 pandemic. The State of Hawai‘i is particularly vulnerable to the spread of influenza due to its unique geographic positioning and heavily trafficked travel patterns. Through the usage of epidemiological research in conjunction with laboratory methods, we are able to trace viral strain origins based on phylogenetic relationships between isolates. In collaboration with the Hawai‘i Department of Health State Laboratory Division, we present a study in which viral isolates collected from individuals in Hawai‘i confirmed as being infected with either seasonal, or pandemic, H1N1 influenza A are extracted, amplified and sequenced for the hemagglutinin and neuraminidase genes to examine evolutionary relationships and spatio-temporal patterns. Implications of molecular data are also supported by epidemiologic information. Phylogenetic analysis suggests that Hawai‘i acts as both a source and sink population for type A influenza virus: in some instances Hawai‘i isolates represented the earliest instance of a strain subsequently seen elsewhere; in other instances Hawai‘i isolates clustered with strains observed earlier in other countries or geographic regions. Through the usage of molecular methods, we hope to develop an improved understanding of influenza dynamics in Hawai‘i. Targeting an area of geographic importance additionally assists in depicting how location and population distribution play a role in the spread of infectious disease. Enhanced comprehension may help to improve efficiency and effectiveness of preparation and response efforts, and reduce the impact of influenza on Hawai‘i and the continental US.