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 Real-time feedback helps save energy and water
08.02.2017 | Otto-Friedrich-Universität Bamberg

nachricht The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>