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West Nile Virus can survive year round in Arizona, spreading to other states, researchers say

Posted at 6:33 AM, Jan 15, 2019
and last updated 2019-01-15 11:10:17-05

PHOENIX — West Nile Virus is no longer a worry restricted to warm weather months -- scientists in Arizona have discovered the potentially deadly virus now lives year round, specifically in Maricopa County.

Researchers have also narrowed down two strains of the virus and have found Arizona is the source for spreading West Nile Virus to other states.

Scientists with Northern Arizona University and Translational Genomics Research Institute (TGen) partnered for a first-of-its-kind study using DNA science pulling directly from infected mosquitoes to build a family tree of the virus.

They found that unlike most places where winter brings a deep freeze that kills off the virus, the moderate climate in Maricopa County has created a safe haven.

"It really needs a good place over winter to be able to survive year round," said Dr. Dave Engelthaler, Director of TGen North and the study's senior author.

He says WNV has been able to tough out the temperature drop in Arizona and wait until warmer temperatures arrive to bring back mosquitoes and birds, which ultimately export the virus to other states.

"Phoenix has been called the land of 10,000 green swimming pools and that becomes an amazing breeding source here in the middle of the desert," said Dr. Engelthaler.

Researchers say the findings don't increase the risk of getting West Nile year round in the Valley, but it does mean the threat will never go away. The next steps for researchers will be to narrow down the areas within the county where the virus is holding on and create a model to determine exactly how it spreads from there.

Dr. Crystal Hepp, one of the study's lead authors and Assistant Professor at NAU, says having this information will help county Vector Control work to reduce the risk of disease in Arizona.

"The protocol we created for this study can now be incorporated into routine public health surveillance activities, allowing for better tracking of local viral hotspots, changes in local viral populations and detection of the emergence of new strains of WNV," Dr. Hepp said.

Funding for the study was provided by the Arizona Technology Research and Initiative Fund and the Arizona Biomedical Research Centre.