Eight spots in Lancaster County are being monitored for mosquitoes that can spread the Zika virus linked to serious birth defects.

Neil Shader, spokesman for the Pennsylvania Department of Environmental Protection, said that’s down from 14 last year, “as the county removed unproductive sites from 2016."

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“The county is concentrating more on the city, especially those areas where there were travel cases,” he said.

The department didn’t say exactly where the spots being monitored are, but plotted them on a rough map. Other than Lancaster city, it appears to show locations in Columbia, Mountville, Manheim and Lititz areas.

Zika can be spread by two types of mosquitoes and by sexual contact, but because its flu-like symptoms are mild and few people who contract the virus notice any symptoms, tracking its spread can be difficult.

More than 200 people in the state have had confirmed or suspected Zika since last spring, but to date, authorities say all are believed to have been contracted outside the state or through sexual contact, not spread by mosquitoes here.

Lancaster is among 21 counties being monitored for the two types of mosquitoes that can spread the virus.

One type of mosquito hasn’t been found in Pennsylvania since 2002. The other type is present here, with several thousand caught in the county and tested last year, none of which were carrying Zika, Shader said.

2017 zika mosquito monitoring lancaster county zoom

Here's a closer look at locations in Lancaster and surrounding counties that will be monitored regularly in 2017 for mosquitoes that could carry the Zika virus. 

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