Summer in York County has been mild, and so has West Nile virus season.
As of Aug. 21, York has had 34 mosquito samples test positive for West Nile virus, according to Pennsylvania West Nile Control Program data. Around this time last year, 38 tested positive; in 2012, that figure was 218.
The virus is transferred to humans by mosquitoes and can cause fever, meningitis and even death in humans, according to the Centers for Disease Control and Prevention.
Two years ago, temperatures warmed up in mid-March, speeding up reproduction for mosquitoes, said Tom Smith, the county's West Nile Virus Program administrator.
This year, winter lasted a long time, which killed off many of the blood-suckers, he said.
With 65 positives, neighboring Adams County has almost twice the amount of positives as York. Adams has seen more rain, as many storms have missed York this summer, Smith said.
"At this point, it's been a little milder (in York) than average. ... We have not been detecting super-high populations," he said, noting that no mosquito spray events are currently planned in the county.
Mosquito surveillance in the county usually stops in the last week of September, once the weather starts to cool down, Smith said.
But the rest of the season is unpredictable because of the weather: Tropical storms or hurricanes can extend it to mid-October, he said.
Other factors: Mosquito prevention efforts, like cleaning up illegal dump sites, have also helped York this year, Smith said. Mosquitoes breed in small pools of water, so cleaning up empty flower pots, kiddie toys and anything that collects water will help quell populations, he said.
"This year has not been that bad, and a lot of it goes back to the cleanups that have occurred in the county," Smith said.
If more people clean up their properties, mosquito problems will go away, he said.
"Everything that people can do now to clean up will greatly reduce mosquito problems next year," Smith said.
Yorkers can report mosquito concerns through the state's West Nile virus website at www.westnile.state.pa.us.
— Reach Mollie Durkin at firstname.lastname@example.org.