Wild Birds and Increased Transmission of Highly Pathogenic Avian Influenza (H5N1) among Poultry, Thailand

Fan

Journal of General Virology

et al. 2020

The predominance of H5N6 in ducks and continuous human cases have heightened its potential threat to public health in China. Therefore, the detection of emerging variants of H5N6 avian influenza viruses has become a priority for pandemic preparedness. Questions remain as to its origin and circulation within the wild bird reservoir and interactions at the wild-domestic interface. Samples were collected from migratory birds in Poyang Lake, Jiangxi Province, PR China during the routine bird ring survey in 2014-16. Phylogenetic and coalescent analyses were conducted to uncover the evolutionary relationship among viruses circulating in wild birds. Here, we report the potential origin and phylogenetic diversity of H5N6 viruses isolated from wild birds in Poyang Lake. Sequence analyses indicated that Jiangxi H5N6 viruses most likely evolved from Eurasian-derived H5Nx and H6N6 viruses through multiple reassortment events. Crucially, the diversity of the HA gene implies that these Jiangxi H5N6 viruses have diverged into two primary clades − clade 2.3.4.4 and clade 2.3.2.1 c. Phylogenetic analysis revealed two independent pathways of reassortment during 2014-16 that might have facilitated the generation of emerging variants within wild bird populations as well as inter-species infections. Our findings contribute to our understanding of the genetic diversification of H5N6 viruses in the wild bird population. These results highlight the necessity of large-scale surveillance of wild birds in the Poyang Lake area to address the threat of regional epizootic epidemics and attendant pandemics.

Section: Discussionmentioning

confidence: 95%

Diversity of avian influenza A(H5N6) viruses in wild birds in southern China

Fan

Journal of General Virology

et al. 2020

“…Surveillance and reporting efforts of national animal disease surveillance systems most commonly target poultry, consequently HPAI in wild birds may go undetected. Therefore, this study did not include outbreaks in wild birds, which can modify the dynamics of the disease (Bahl et al., ; Hesterberg et al., ; Tian et al., ) not only at the international level, which is well‐recognized (Feare, ; The Global Consortium for H5N8 and Related Influenza Viruses, ), but also at the country level (Keawcharoen et al., ; Rappole & Hubálek, ). Applying the methods used in this paper for HPAI outbreaks in wild birds would require preliminary modelling to correct for the effects of significant reporting gaps.…”

Section: Discussionmentioning

confidence: 99%

Global dynamics of highly pathogenic avian influenza outbreaks in poultry between 2005 and 2016-Focus on distance and rate of spread

Awada

Tizzani

Noh

et al. 2018

Transbound Emerg Dis

Highly pathogenic avian influenza (HPAI) is of major importance for human and animal health because of high morbidity and mortality in poultry and the potential for transmission of this zoonotic pathogen to humans. Knowledge of HPAI epidemiology in avian populations and practical information on the temporal and spatial spread of the disease after introduction into a country is important in order to enhance the capacity of predicting and managing epidemics to minimize the negative impacts on human and animal health. Using data reported to the World Organisation for Animal Health between 2005 and 2017 by 199 countries for 14,129 outbreaks in poultry, we used a spatial and time-series analysis to determine that: (a) During the last 12 years, there were two major global peaks in the number of countries affected by HPAI with 23% and 26% of countries affected in 2006 and 2016. (b) Based on the seasonality analysis, spread is the lowest in September, begins to rise in October, and peaks in February. (c) The median distance HPAI outbreaks spread from the index outbreak was 111 km, while the median apparent rate of spread of outbreaks was 1.9 km/day. (d) In 39% of HPAI events, the disease did not spread beyond the index outbreak and the median maximum spread from the index outbreak per event was 45 km. (e) The distance HPAI outbreaks spread from the index outbreak was significantly negatively correlated with the number of outbreaks during the same time period, indicating that the spread of HPAI was lower during global panzootics than during periods of low transmission. These findings are of major importance for veterinary services to design and implement surveillance measures for improving preparedness to minimize the impacts of this disease.

Journal of Applied Statistics

“…To study the epidemiology of this viral infection among poultry in Thailand from 2004 through 2007, it was investigated how wild birds play a role in transmission. See [9] for a full description of the research and of the data. The question was: does the joint presence of infected wild birds and poultry increase spread among poultry flocks?…”

Section: The H5n1 Avian Influenza Outbreak In Thailand (2004-2007)mentioning

confidence: 99%

“…We could therefore only use these 3 sub-regions to investigate whether the presence of infected wild birds was related to the poultry outbreak. Within these 3 areas, a wild bird infected month was defined as a month in which infected wild birds were detected or which showed wild bird infection in the preceding month [9]. The idea is that the reproductive power (probability) between poultry flocks might be higher in these months compared to other months because there was 'help' from wild birds.…”

Section: The H5n1 Avian Influenza Outbreak In Thailand (2004-2007)mentioning

confidence: 99%

Modelling the reproductive power function

Broek

2020

Self Cite

This paper discusses methods of estimating the reproductive power and the accompanying survival function of communicable events, e.g. infectious disease transmission. The early stage of an outbreak can be described by the infectiousness of the outbreak process, but in later stages of the outbreak, this is complicated by factors such as changing contact patterns and the impact of control measures. It is important to take these factors into account in order to get a good, if approximate, model for an outbreak process. This paper proposes a non-homogeneous birth process and regression model for the reproductive power function, similar to models in discrete survival analysis. A baseline reproductive power function gives a description of the outbreak when covariates are at their baseline values. As an illustration these methods are applied to an avian influenza (H5N1) outbreak among poultry in Thailand.