Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Effects of Climate Change on West Nile Virus

10.09.2013
The varied influence of climate change on temperature and precipitation may have an equally wide-ranging effect on the spread of West Nile virus, suggesting that public health efforts to control the virus will need to take a local rather than global perspective, according to a study published this week in the scientific journal Proceedings of the National Academy of Sciences.

University of Arizona researchers Cory Morin and Andrew Comrie developed a climate-driven mosquito population model to simulate the abundance across the southern United States of one type of mosquito known to carry and spread West Nile virus to humans.


Known as a vector for the West Nile virus, this Culex quinquefasciatus mosquito has landed on a human finger. Eliminating puddles and small containers of water can greatly reduce this mosquito's population. (Photo: CDC/Jim Gathany)

They found that, under the future climate conditions predicted by climate change models, many locations will see a lengthening of the mosquito season but shrinking summer mosquito populations due to hotter and dryer conditions allowing fewer larvae to survive.

However, these changes vary significantly depending on temperature and precipitation. For example, drops in summer mosquito populations are expected to be significant in the South, but not further north where there will still be enough rain to maintain summer breeding habitats and extreme temperatures are less common. These findings suggest that disease transmission studies and programs designed to control populations of disease-carrying mosquitos must be targeted locally to maximize their effectiveness, the authors argue.

"It used to be an open question whether climate change is going to make disease-carrying mosquitoes more abundant, and the answer is it will depend on the time and the location," said Morin, who did the study as part of his doctoral dissertation in the lab of Comrie, UA provost and professor in the UA's School of Geography and Development. Morin is now a postdoctoral researcher on Comrie's team.

"One assumption was that with rising temperatures, mosquitoes would thrive across the board," Morin said. "Our study shows this is unlikely. Rather, the effects of climate change are different depending on the region and because of that, the response of West Nile virus transmitting mosquito populations will be different as well."

"The mosquito species we study is subtropical, and at warmer temperatures the larvae develop faster," Morin explained. "However, there is a limit – if temperatures climb over that limit, mortality increases. Temperature, precipitation or both can limit the populations, depending on local conditions."

In the southwestern U.S. for example, hotter and drier summers are expected to delay the onset of mosquito season; however, late summer and fall rains are expected to result in a longer season. Conversely, the south-central U.S. will see fewer mosquito days due to less rain during summer and early fall. Higher temperatures projected for the shoulder seasons – spring and fall – will likely make for a longer mosquito season across much of the U.S., except in the Southwest during spring where severe drying inhibits population development.

Morin pointed out that while the study focused on one important part in West Nile virus' infectious cycle – mosquitoes of the species Culex quinquefasciatus – there are other mosquito species that transmit the virus. Furthermore, the virus also infects birds, another part in the cycle that was not included in the model simulations.

A so-called container breeder, Culex quinquefasciatus lays its eggs in small volumes of standing water. The larvae therefore depend heavily on precipitation, unlike species that prefer larger bodies of water such as lakes.

According to the Centers for Disease Control (CDC), 70 to 80 percent of people infected with West Nile virus do not develop symptoms. The remaining 20 percent will have flu-like symptoms for a week or two, while severe effects are limited to less than 1 percent of infected individuals. They include encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord) and mostly affect the elderly and individuals with compromised immune response.

First detected in North America in 1999, West Nile virus has since spread across the continental United States and Canada. Cases of humans infected with West Nile virus have been documented in every state in the contiguous United States. The areas of major epidemics vary from year to year. The largest most recent outbreak occurred in Texas in 2012, with 1,868 disease cases reported to the CDC.

"'Which locations are likely to experience epidemics in the future?' – those are the kinds of questions studies like ours may help prepare for," said Morin. "We don't model the actual virus, we only look at the vector, but our study informs at least one part of the ecology of the virus. It is unique in projecting the impacts of climate change on a West Nile vector."

Morin said the study could help managers and decision makers better anticipate how mosquito populations will respond to changes in climate and prepare accordingly.

"For example, if projected precipitation and temperature changes for a given area are indicating a longer mosquito season, public health officials can plan to adapt to that possibility through abatement and awareness campaigns.
This story and photos are online:
http://uanews.org/story/effects-of-climate-change-on-west-nile-virus
Contacts
Sources:
Cory W. Morin, 603-498-1246, cmorin@email.arizona.edu

Andrew C. Comrie, comrie@email.arizona.edu

UANews contact:
Daniel Stolte, 520-954-1964, stolte@email.arizona.edu

Daniel Stolte | University of Arizona
Further information:
http://www.arizona.edu
http://uanews.org/story/effects-of-climate-change-on-west-nile-virus

More articles from Studies and Analyses:

nachricht Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Subaru Telescope helps pinpoint origin of ultra-high energy neutrino

16.07.2018 | Physics and Astronomy

Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides

16.07.2018 | Life Sciences

New research calculates capacity of North American forests to sequester carbon

16.07.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>