Avian Influenza Research Today is a free monthly online journal that collates and summarizes the latest research about Avian Influenza, including details on bird flu, h5n1, risks, vaccines, prevention.

Mapping H5N1 highly pathogenic avian influenza risk in Southeast Asia.

Gilbert M, Xiao X, Pfeiffer DU, Epprecht M, Boles S, Czarnecki C, Chaitaweesub P, Kalpravidh W, Minh PQ, Otte MJ, Martin V, Slingenbergh J

Biological Control and Spatial Ecology, Université Libre de Bruxelles, CP160/12, Avenue FD Roosevelt 50, B-1050 Brussels, Belgium. mgilbert@ulb.ac.be

The highly pathogenic avian influenza (HPAI) H5N1 virus that emerged in southern China in the mid-1990s has in recent years evolved into the first HPAI panzootic. In many countries where the virus was detected, the virus was successfully controlled, whereas other countries face periodic reoccurrence despite significant control efforts. A central question is to understand the factors favoring the continuing reoccurrence of the virus. The abundance of domestic ducks, in particular free-grazing ducks feeding in intensive rice cropping areas, has been identified as one such risk factor based on separate studies carried out in Thailand and Vietnam. In addition, recent extensive progress was made in the spatial prediction of rice cropping intensity obtained through satellite imagery processing. This article analyses the statistical association between the recorded HPAI H5N1 virus presence and a set of five key environmental variables comprising elevation, human population, chicken numbers, duck numbers, and rice cropping intensity for three synchronous epidemic waves in Thailand and Vietnam. A consistent pattern emerges suggesting risk to be associated with duck abundance, human population, and rice cropping intensity in contrast to a relatively low association with chicken numbers. A statistical risk model based on the second epidemic wave data in Thailand is found to maintain its predictive power when extrapolated to Vietnam, which supports its application to other countries with similar agro-ecological conditions such as Laos or Cambodia. The model's potential application to mapping HPAI H5N1 disease risk in Indonesia is discussed.

Published 26 March 2008 in Proc Natl Acad Sci U S A, 105(12): 4769-74.
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Articles on Avian Influenza published 12 March 2008:

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The transmission of highly pathogenic avian influenza H5N1 virus to Southeast Asian countries triggered the first major outbreak and transmission wave in late 2003, accelerating the pandemic threat to the world. Due to the lack of influenza surveillance prior to these outbreaks, the genetic diversity and the transmission pathways of H5N1 viruses from this period remain undefined. To determine the possible source of the wave 1 H5N1 viruses, we recently conducted further sequencing and analysis ... [Abstract] [Full-text]

Articles on Avian Influenza published 11 December 2007:

A naturally occurring deletion in its NS gene contributes to the attenuation of an H5N1 swine influenza virus in chickens.   J Virol, 82(1): 220-8.

In 2001 and 2003, we isolated two H5N1 viruses, A/swine/Fujian/1/01 (SW/FJ/01) and A/swine/Fujian/1/03 (SW/FJ/03), from pigs in Fujian Province, southern China. Genetically, these two viruses are similar, although the NS gene of the SW/FJ/03 virus has a 15-nucleotide deletion at coding positions 612 to 626. The SW/FJ/01 virus is highly lethal for chickens, whereas the SW/FJ/03 virus is nonpathogenic for chickens when administrated intravenously or intranasally. To understand the molecular basis ... [Abstract] [Full-text]

Articles on Avian Influenza published 16 November 2007:

Lack of evidence of avian-to-human transmission of avian influenza A (H5N1) virus among poultry workers, Kano, Nigeria, 2006.   J Infect Dis, 196(11): 1685-91.

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Transmission of the highly pathogenic avian influenza virus H5N1 within flocks during the 2004 epidemic in Thailand.   J Infect Dis, 196(11): 1679-84.

This present study is the first to quantify the transmission of avian influenza virus H5N1 within flocks during the 2004 epidemic in Thailand. It uses the flock-level mortality data to estimate the transmission-rate parameter ( beta ) and the basic reproduction number (R(0)). The point estimates of beta varied from 2.26/day (95% confidence interval [CI], 2.01-2.55) for a 1-day infectious period to 0.66/day (95% CI, 0.50-0.87) for a 4-day infectious period, whereas the accompanying R(0) varied ... [Abstract] [Full-text]

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Highly pathogenic avian influenza H5N1 viruses elicit an attenuated type i interferon response in polarized human bronchial epithelial cells.   J Virol, 81(22): 12439-49.

The unparalleled spread of highly pathogenic avian influenza A (HPAI) H5N1 viruses has resulted in devastating outbreaks in domestic poultry and sporadic human infections with a high fatality rate. To better understand the mechanism(s) of H5N1 virus pathogenesis and host responses in humans, we utilized a polarized human bronchial epithelial cell model that expresses both avian alpha-2,3- and human alpha-2,6-linked sialic acid receptors on the apical surface and supports productive replication ... [Abstract] [Full-text]

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Origin of highly pathogenic H5N1 avian influenza virus in China and genetic characterization of donor and recipient viruses.   J Gen Virol, 88: 3094-9.

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Articles on Avian Influenza published 15 October 2007:

Characterization of low-pathogenicity H5N1 avian influenza viruses from North America.   J Virol, 81(21): 11612-9.

Wild-bird surveillance in North America for avian influenza (AI) viruses with a goal of early identification of the Asian H5N1 highly pathogenic AI virus has identified at least six low-pathogenicity H5N1 AI viruses between 2004 and 2006. The hemagglutinin (HA) and neuraminidase (NA) genes from all 6 H5N1 viruses and an additional 38 North American wild-bird-origin H5 subtype and 28 N1 subtype viruses were sequenced and compared with sequences available in GenBank by phylogenetic analysis. Both ... [Abstract] [Full-text]

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