Evening and overnight activities have been suspended in three Suffolk parks after mosquito samples from each park tested positive for West Nile virus, the Suffolk County health department said Thursday.

Health officials say they have advised administrators to suspend activities from 6 p.m. to 8 a.m. at Blydenburgh County Park, Smithtown, Connetquot State Park, Oakdale, and Girl Scout Day Camp Sobaco, Yaphank.

The samples, collected Aug. 3 and 4, were all Culex pipiens-restuans, and those evening and overnight hours are when that mosquito is most active, health officials said.

Besides those three, 17 more samples tested positive for West Nile, those collected on July 27 from Jamesport (1) and on Aug. 3 and 4 from Copiague (1), West Babylon (1), Selden (1), Setauket (1), Aquebogue (5), Huntington Station (1), Northport (1), Melville (1), Holbrook (1) and Holtsville (3).

That brings the total to 57 samples, all Culex pipiens-restuans mosquitoes, as well as six birds that have tested positive for West Nile.

Zika virus has not been found in any Suffolk mosquitoes, officials said.

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Nassau County is reporting one positive mosquito sample, collected June 29 in Farmingdale, a health department spokeswoman said.

Some mosquito bites can transmit West Nile to humans, with mosquitoes picking up the virus by feeding on infected birds.

“The confirmation of West Nile virus in mosquito samples or birds indicates the presence of West Nile virus in the area,” said Dr. James L. Tomarken, Suffolk County health services commissioner.

“While there is no cause for alarm, we urge residents to cooperate with us in our efforts to reduce the exposure to the virus, which can be debilitating to humans.”

The virus may cause serious neurological illnesses that could lead to health conditions or death, health officials say.

Last year Suffolk County saw five human West Nile cases and no deaths, with Nassau reporting nine human cases and no deaths.

Also last year, 2,060 human cases of West Nile were reported in the United States, resulting in 119 deaths, based on information as of mid-January, according to the Centers for Disease Control and Prevention.

Health officials say residents can help make areas around their homes unfriendly to mosquitoes by:

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  • Regularly looking for and eliminating even the smallest amounts of standing water, which is where the insects reproduce. That could include in cans, buckets and other containers, as well as old tires, tarps, pool covers and children’s toys.
  • Drilling drainage holes at the bottom of garbage cans, changing birdbath water at least weekly and making sure roof gutters are unclogged and draining properly.
  • Adding fish to circulate water in any backyard ponds, and clearing pond edges of debris and vegetation.