Climate Change Driving Increase In West Nile Virus Cases Across Montco

NORRISTOWN, PA — Health officials in Montgomery County have discovered a sharp increase in positive tests in mosquitoes in the past few weeks, a rise that ecologists say is at least partly due to the effects of climate change.

It's not unusual for mosquito activity to increase in late summer, but what is of chief concern is the samples that have tested positive for disease. Thus far, West Nile Virus is the main culprit in Montgomery County.

Royersford, Limerick, Whitpain, Norristown, East Norriton, Montgomery Township, Upper Providence, and Lower Providence have all had positive tests within the past two weeks. Each community has also had at least one chemical spraying from the health department in an attempt to reduce the mosquito population.

Elsewhere along the eastern seaboard, such as in Massachusetts, mosquitoes have tested positive for the deadly eastern equine encephalitis virus, which kills around 30 percent of people who are infected.

There are many drivers for the increase in West Nile cases and other diseases. Chief among them is climate change: shorter winters and longer summers mean more breeding time for mosquitoes, and it also helps the virus spread faster and incubate faster within a mosquito, according to the EPA. Heavier than normal rainfall will also leave more standing water than in the past, and mosquitoes rely on pools of stagnant water to breed.

In addition, the fragmentation of forests and reduction of other insects, birds, and mammals that prey on mosquitoes has allowed their populations to thrive.