Open AccessInferring epidemiologic dynamics from viral evolution: 2014–2015 Eurasian/North American highly pathogenic avian influenza viruses exceed transmission threshold, R 0 = 1, in wild birds and poultry in North America
Author(s) -
Grear Daniel A.,
Hall Jeffrey S.,
Dusek Robert J.,
Ip Hon S.
Publication year - 2018
Publication title -
evolutionary applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.776
H-Index - 68
ISSN - 1752-4571
DOI - 10.1111/eva.12576
Subject(s) - reassortment , biology , influenza a virus subtype h5n1 , outbreak , population , viral evolution , bird migration , transmission (telecommunications) , viral phylodynamics , virology , influenza a virus , lineage (genetic) , virus , zoology , phylogenetic tree , ecology , genetics , infectious disease (medical specialty) , gene , disease , covid-19 , medicine , pathology , genome , electrical engineering , engineering , demography , sociology
Highly pathogenic avian influenza virus ( HPAIV ) is a multihost pathogen with lineages that pose health risks for domestic birds, wild birds, and humans. One mechanism of intercontinental HPAIV spread is through wild bird reservoirs, and wild birds were the likely sources of a Eurasian ( EA ) lineage HPAIV into North America in 2014. The introduction resulted in several reassortment events with North American ( NA ) lineage low‐pathogenic avian influenza viruses and the reassortant EA / NA H5N2 went on to cause one of the largest HPAIV poultry outbreaks in North America. We evaluated three hypotheses about novel HPAIV introduced into wild and domestic bird hosts: (i) transmission of novel HPAIV s in wild birds was restricted by mechanisms associated with highly pathogenic phenotypes; (ii) the HPAIV poultry outbreak was not self‐sustaining and required viral input from wild birds; and (iii) reassortment of the EA H5N8 generated reassortant EA / NA AIV s with a fitness advantage over fully Eurasian lineages in North American wild birds. We used a time‐rooted phylodynamic model that explicitly incorporated viral population dynamics with evolutionary dynamics to estimate the basic reproductive number ( R 0 ) and viral migration among host types in domestic and wild birds, as well as between the EA H5N8 and EA / NA H5N2 in wild birds. We did not find evidence to support hypothesis (i) or (ii) as our estimates of the transmission parameters suggested that the HPAIV outbreak met or exceeded the threshold for persistence in wild birds ( R 0 > 1) and poultry ( R 0 ≈ 1) with minimal estimated transmission among host types. There was also no evidence to support hypothesis (iii) because R 0 values were similar among EA H5N8 and EA / NA H5N2 in wild birds. Our results suggest that this novel HPAIV and reassortments did not encounter any transmission barriers sufficient to prevent persistence when introduced to wild or domestic birds.