West Nile Virus On The Rise. Is Climate Change To Blame?

Oct 15, 2018

There have been six cases of West Nile Virus in Allegheny County so far this year, the highest in more than a decade.

Most people infected with West Nile won’t show symptoms. On rare occasions it develops into a severe, potentially fatal neurological disease.

Though six is not a large number, this increase is a trend that’s projected to continue. Climate change is making the environment in western Pennsylvania more humid and therefore more amendable to mosquitoes, which transmit West Nile to people.

“Climate change is happening,” said Karen Hacker, director of the community health department. “What we're trying to do in public health is deal with the ramifications of climate change which include this increase in vector borne illnesses.”

Allegheny County has also been contending with an increase in Lyme Disease, which is transmitted by ticks.

William Klimstra studies mosquito-transmitted viruses at the University of Pittsburgh. He said while the changing climate certainly amplifies the spread of mosquito-borne diseases overtime, he doubts its responsible for this year's sudden uptick.

Rather, other factors are likely at play.

“Human behavior can change from year-to-year. People being active during times of the day when the mosquitoes are active and are feeding,” he said. “It can also be that human development encroaches on areas that historically were not utilized by humans, and so if there are more mosquitoes abundant in those areas you get more cases.”

To prevent mosquito bites, people should get rid of standing water and wear long sleeves and repellent when they go outside.

In areas were samples have tested positive for West Nile, the county has sprayed Zenivex E20, a pesticide that is not harmful to humans or pets.

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