Free-grazing Ducks and Highly Pathogenic Avian Influenza, Thailand

Gilbert, Marius; Chaitaweesub, Prasit; Parakamawongsa, Tippawon; Premashthira, Sith; Tiensin, Thanawat; Kalpravidh, Wantanee; Wagner, H; Slingenbergh, Jan

doi:10.3201/eid1202.050640

Cited by 301 publications

(349 citation statements)

References 13 publications

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“…Given the indication that the 2004 HPAI outbreaks were strongly associated with free grazing ducks, this husbandry practice was subjected to much focus in terms of HPAI surveillance and preventive measures, including (i) registration and surveillance of all flocks (when HPAI H5N1 positive, stamping out and compensation followed), (ii) premovement testing, and (iii) provision of incentives for improved biosecurity and shift from free grazing husbandry into farm ducks. These measures were arguably effective in reducing the number of HPAI outbreaks during 2005, when HPAI was still present in Thailand but at a much lower level (Gilbert et al, 2006). In 2005/2006, Thailand was still in a transition phase when, despite incentive measures, free grazing duck were still found in high numbers in the central plains, and when duck flocks were still undertaking sub-provincial movements.…”

Section: Discussionmentioning

confidence: 99%

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Avian influenza, domestic ducks and rice agriculture in Thailand

Gilbert

Xiao

Chaitaweesub

et al. 2007

Agriculture, Ecosystems & Environment

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118

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Highly pathogenic avian influenza (HPAI) caused by H5N1 viruses has become a global scale problem which first emerged in southern China and from there spread to other countries in Southeast and East Asia, where it was first confirmed in end 2003. In previous work, geospatial analyses demonstrated that free grazing ducks played critical role in the epidemiology of the disease in Thailand in the winter 2004/2005, both in terms of HPAI emergence and spread. This study explored the geographic association between free grazing duck census counts and current statistics on the spatial distribution of rice crops in Thailand, in particular the crop calendar of rice production. The analysis was carried out using both district level rice statistics and rice distribution data predicted with the aid of remote sensing, using a rice-detection algorithm. The results indicated a strong association between the number of free grazing ducks and the number of months during which second-crop rice harvest takes place, as well as with the rice crop intensity as predicted by remote sensing. These results confirmed that free grazing duck husbandry was strongly driven by agricultural land use and rice crop intensity, and that this later variable can be readily predicted using remote sensing. Analysis of rice cropping patterns may provide an indication of the location of populations of free grazing ducks in other countries with similar mixed duck and rice production systems and less detailed duck census data. Apart from free ranging ducks and rice cropping, the role of hydrology and seasonality of wetlands and water bodies in the HPAI risk analysis is also discussed in relation to the presumed dry season aggregation of wild waterfowl and aquatic poultry offering much scope for virus transmission.

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Section: Discussionmentioning

confidence: 99%

“…In previous work, the geospatial distribution of HPAIH5N1 outbreaks in Thailand during the second wave of disease outbreaks was analysed, using outbreaks reported from the second half of 2004 to mid 2005 (Gilbert et al, 2006). The results demonstrated a very strong association between HPAI outbreaks and the density of free grazing ducks.…”

Section: Introductionmentioning

confidence: 97%

Avian influenza, domestic ducks and rice agriculture in Thailand

Gilbert

Xiao

Chaitaweesub

et al. 2007

Agriculture, Ecosystems & Environment

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118

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“…Evidence supports the proposition that contact among freegrazing poultry (Wang et al, 2013), backyard poultry and wild birds (Gilbert et al, 2006) has contributed to the spread of H5N1 influenza virus. In African countries and Turkey, it is common practice to keep multispecies poultry in a free-range system.…”

Section: Cross-species Virus Transmission Networkmentioning

confidence: 65%

Genetic evidence for avian influenza H5N1 viral transmission along the Black Sea–Mediterranean Flyway

Zhou

Tian

et al. 2016

Journal of General Virology

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The current epidemic of highly pathogenic avian influenza H5N1 virus is considered to pose a significant threat to the health of wild and domestic avian species, and even to human beings. The Black Sea-Mediterranean Flyway is one of the most important epidemic areas of H5N1. However, the epidemic along this flyway has not been fully explored. To better understand the role of hosts in the spread and evolution of H5N1 virus along the flyway, a phylogeographic study was conducted using haemagglutinin (HA) gene sequences obtained during [2005][2006][2007][2008][2009][2010][2011][2012][2013]. To infer phylodynamic spread in time and space, we used a flexible Bayesian statistical framework and modelled viral spatial diffusion as a continuous-time Markov-chain process along timemeasured genealogies. Our results revealed that H5N1 virus isolated from wild birds showed an increase in genetic variation of HA gene from [2005][2006][2007]. The mean genetic distance of viruses isolated from poultry reached its peak in 2010, and dropped in 2011, increasing again in 2012-2013. The reconstruction of virus circulation revealed a different viral-migration network of H5N1 virus by different hosts. Western Russia constituted a link in viral migration from Russia to Europe and Africa. Cross-species transmission of H5N1 viruses predominated in the migration network of the Black Sea-Mediterranean Flyway. This might be due to the migration of birds across long distances and interaction between local poultry and migratory birds. Additionally, the short-distance spread of H5N1 viruses among poultry followed local transportation networks. Such findings will aid in developing effective disease control and prevention strategies.

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“…Because of the high number of outbreaks in the Central region (14,17,20), it was further divided into 6 parts: central–northwest, central–north, central–central, central–east, central–southeast, and central–southwest. On the basis of procedures established by the Thai Meteorological Department, the seasons were divided into 3 periods: summer (March–June), the rainy season (July–October), and winter (November–February).…”

Section: Methodsmentioning

confidence: 99%