Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Migratory Birds, domestic poultry and avian influenza

06.04.2011
The persistence and recurrence of H5N1 avian influenza in endemic regions can largely be blamed on movement and infection by migratory birds.

Trade in poultry, poultry products and caged birds, and movement of wild birds also account for H5N1 prevalence in these areas. Several recent outbreaks of avian influenza have suggested strong evidence of migratory birds playing a role in transmitting the virus over long distances.

In a paper published last week in the SIAM Journal on Applied Mathematics, authors Lydia Bourouiba, Stephen A. Gourley, Rongsong Liu, and Jianhong Wu analyze the interaction between non-migratory poultry and migratory birds in order to investigate the role of the latter in the spread of H5N1.

Although avian influenza rarely infects humans, occasional cases of human infection have been observed since the late nineties. Moreover, it is a huge problem in the poultry industry since infected flocks can cause a drain on resources and threaten food supply. It can also result in significant reduction in wild bird populations, which is of great ecological concern.

“How the interaction of a migratory bird species with domestic poultry contributes to the spread and persistence of the highly pathogenic H5N1 virus is a question of profound importance to the control of avian influenza spread, and to the effort of mitigating the impact of the disease on the domestic poultry industry,” says corresponding author Stephen Gourley, researcher in the Department of Mathematics at the University of Surrey. “Answering this question requires a truly interdisciplinary approach involving collaborations from different fields. Mathematical modeling can play a significant role in solving such a complex problem in which experiments are difficult and surveillance data is limited.”

In order to determine how migratory birds might contribute to disease in poultry, the authors first analyze the susceptibility of migratory birds to infection by using a model to trace their path along flyways. “Patches” represent 4 locations: breeding and wintering sites, and layovers on outgoing and return routes where birds stop to rest and feed. The migration flyway is expressed mathematically by a one-dimensional closed curve starting and ending at the breeding patch. Reaction-advection equations describe the migration of birds along this flight path.

The quantity of birds susceptible to infection is calculated by determining the density of susceptible birds along the flying route. The time of journey for the susceptible birds is the distance between each patch divided by their mean flight velocity. In-flight mortalities are also accounted for in the equation. Assuming that migratory birds can only contract the virus while in patches (and not while in transit), the probability of infection of a bird is determined based on its contact rate with infected migratory birds and infected poultry, and time spent in a patch. The time of stay depends on several factors, such as the rate at which birds enter the patch, length and duration of their journey, energy consumed on their incoming flight, and the nourishment required to proceed.

The model factors in the observation that birds encounter very different conditions at different stages on their migration route. In reality, migratory birds have more than a single stopover in their fall and spring routes; these are lumped together as one each for the sake of simplicity. The population of poultry on each patch is assumed to be a constant, as is the length of the flyway and average flight velocity.

The Common Teal in flight - Photo courtesy of orientalbirdimages.org
Using their model, the authors analyze the dynamics of migratory Common Teals and their interaction with farmed poultry in the Poyang Lake area of China. Their simulations demonstrate that the arrival of migratory birds in winter can introduce avian influenza to poultry in disease-free periods. Once the flu becomes endemic in the wintering location, the result is sustenance of the flu in migratory birds themselves. “It is amazing that our model, which starts from surprisingly simple assumptions, can predict when there will be an outbreak of the disease, and how limited data from the Chinese Poyang Lake region can be used to parametrize and validate the model,” says Gourley.

Future research should be focused on finding tools that can predict peak disease times, according to the researchers. “Some of our computer simulations suggest that peak disease activity will not always occur in a regular predictable pattern,” Gourley explains. “Irregular intervals from peak to peak pose significant challenges for future theoretical research. Tools that can estimate peak times will be important for designing effective surveillance and for planning intervention strategies.”

In addition, integrating such research with data from international migratory bird surveillance and commercial poultry trade can shed more light on these interactions on a global scale. Many national and international organizations are involved in these efforts. The United States Geological Survey (USGS) has been working in partnership with the United Nations Food and Agricultural Organization (UN FAO) to study the role of wild birds in the geographic spread of H5N1.

“It would be great to have more information about global surveillance of migratory birds and commercial poultry trading so that [our] model can be expanded to understand the disease spread along the network of migratory flyways and commercial trading,” says Gourley. “This shows the importance of continuing and enhancing the current work of the UN FAO and the US Geological Survey.”

Source:

The interaction of Migratory Birds and Domestic Poultry and its role in sustaining Avian Influenza

Lydia Bourouiba, Stephen A. Gourley, Rongsong Liu, and Jianhong Wu

SIAM Journal on Applied Mathematics, 71 (2011), pp 487-516

Pub date: March 29, 2011

Karthika Muthukumaraswamy | EurekAlert!
Further information:
http://www.siam.org

More articles from Life Sciences:

nachricht New photocatalyst speeds up the conversion of carbon dioxide into chemical resources
29.05.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)

nachricht Copper hydroxide nanoparticles provide protection against toxic oxygen radicals in cigarette smoke
29.05.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

New insights into the ancestors of all complex life

29.05.2017 | Earth Sciences

New photocatalyst speeds up the conversion of carbon dioxide into chemical resources

29.05.2017 | Life Sciences

NASA's SDO sees partial eclipse in space

29.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>