DEP: Zika Virus Mosquito Type At Pest Levels In 13 Counties, No Virus Found

The Department of Environmental Protection Tuesday released results of surveillance for Aedes mosquitoes, which have been found to be vectors of the Zika virus.

At this time, there have not been any cases of Zika transmitted locally in Pennsylvania, nor have mosquitoes tested positive for the virus.

The following counties were found to have pest levels of Aedes mosquitoes-- Allegheny, Beaver, Berks, Bucks, Dauphin, Delaware, Fayette, Franklin, Lancaster, Lehigh, Montgomery, Philadelphia and York

Twenty-six counties in Pennsylvania have active surveillance sites for albopictus mosquitoes, commonly known as Asian Tiger mosquitoes. The mosquitoes are predominantly found in southern and eastern counties.

There have not been any specimens of Aedes aegypti collected, which are the primary carrier of Zika in South America. Aedes aegypti have not been found in Pennsylvania since 2002.

Counties conducting surveillance and approximate locations can be found beginning on page 15 of the DEP/PA Department of Health Zika Response Plan.

Surveillance Results

Surveillance statistics for the week ending July 30 are below.

-- Southwest PA: The following counties in southwest PA have recorded the presence of Aedes albopictus, but populations haven’t reached pest levels: (Pest levels are defined as greater than 24 female Aedes albopictus per trapping event): Beaver; Allegheny; and Fayette.

Surveillance conducted in Blair and Cambria counties each recorded zero specimens

-- Southcentral PA: The following counties in southcentral PA recorded an average of more than 24 Aedes albopictus mosquitoes per trap (Pest levels are defined as greater than 24 female Aedes albopictus per trapping event): Franklin; York; Dauphin; Lancaster; and Berks

The following counties in southcentral PA recorded the presence of Aedes albopictus, but populations have not reached pest level: Adams; Cumberland; and Lebanon.

-- Northeast PA: In northeast PA, surveillance in Lehigh County has found pest levels of Aedes albopictus during the last week of July (Pest levels are defined as greater than 24 female Aedes albopictus per trapping event).  

Aedes albopictus has been found in Northampton County, but the pest levels haven’t been observed.

Surveillance in Lackawanna, Luzerne, and Monroe counties began on August 8.

-- Southeast PA: The following counties in southeast PA have recorded pest levels of Aedes albopictus at least one week during July: (Pest levels are defined as greater than 24 female Aedes albopictus per trapping event): Bucks; Montgomery; Delaware; and Philadelphia.

The following counties in southeast PA have recorded the presence of Aedes albopictus, but populations have not reached pest levels. Chester

In addition, in early August, DEP and the Philadelphia Department of Public Health and the Chester County Health Department responded to two imported cases of per the protocols outlined in the  Zika Response Plan for clusters, or cases, of Zika.

Imported cases of Zika were identified by the Department of Health, which works closely with DEP to identify clusters and initiate an appropriate response.  

Mosquitoes collected in the Philadelphia cluster response activities were tested for Zika and all samples came back negative.

Mosquito trapping in Chester County did not find significant populations of the Asian tiger mosquito and samples were not tested.

“The surveillance and cluster response by DEP and county governments has gone exactly to the Zika response plan, and I am pleased to note that there is no evidence of the Zika virus being carried by mosquitoes in Pennsylvania,” said acting DEP Secretary Patrick McDonnell. “I want to continue to encourage residents to take common-sense actions like wearing insect repellant and eliminating standing water to cut down on mosquito activity.”

The counties were surveillance is taking place include: Adams, Allegheny, Beaver, Berks, Blair, Bucks, Cambria, Centre, Chester, Cumberland, Dauphin, Delaware, Erie, Fayette, Franklin, Lackawanna, Lancaster, Lawrence, Lebanon, Lehigh, Luzerne, Monroe, Montgomery, Northampton, Philadelphia and York.

Prevention Measures

DEP recommends that residents do simple activities to reduce mosquito activity in their areas:

--   Dispose of cans, buckets, plastic containers, ceramic pots, or similar containers that hold water;

--  Properly dispose of discarded tires that can collect water. Stagnant water is where most mosquitoes breed;

-- Drill holes in the bottom of outdoor recycling containers;

-- Have clogged roof gutters cleaned every year as the leaves from surrounding trees have a tendency to plug drains;

-- Turn over wheelbarrows and plastic wading pools when not in use and don't let water stagnate in birdbaths;

-- Aerate ornamental pools or stock them with fish;

-- Clean and chlorinate swimming pools not in use and remove any water that may collect on pool covers;

-- Wear insect repellant during times of mosquito activity. Aedes mosquitoes are active during daylight hours; and

-- Keep doors and windows tightly closed, or ensure that screens do not have holes or tears that can allow mosquitoes to get inside the house

“These mosquitoes are weak fliers, so if you see them, they are likely breeding nearby,” said Matt Helwig, program specialist in DEP’s Vector Management program. “Simple precautions to eliminate potential habitat and avoid contact can lead to a safe and itch-free summer.”

For more information, visit the Department of Health’s Zika Virus webpage.