Two more human cases of West Nile virus have been confirmed in Nassau County, bringing the county's total to three so far this year, a health department spokeswoman said Friday.

Nassau's new cases involve a Town of Oyster Bay woman, older than 55, who saw the onset of symptoms in mid-August and is now recovering, and a man over 60 in the Town of North Hempstead who became sick in late August, was hospitalized and is now home recovering, health department spokeswoman Mary Ellen Laurain said.

The county's first case of 2015 was in a woman younger than 50 in the Town of Oyster Bay. She was hospitalized with the disease in mid-August and also is recovering.

Suffolk County health officials reported one human case on Sept. 10 -- a Town of Islip man older than 50 who had been hospitalized with the illness.

In some cases, the virus causes serious neurological illnesses that can lead to permanent conditions, including death. Some mosquito bites can transmit West Nile to humans, with mosquitoes picking up the virus by feeding on infected birds.

Nassau reported 56 mosquito samples that have tested positive this year for the virus, while Suffolk Friday reported 21 new positive samples that were collected Sept. 9-10 in North Babylon, West Babylon, Huntington, Huntington Station, Northport, Dix Hills, Smithtown, Nesconset, West Islip, Islip, Holbrook, Holtsville, Farmingville, Selden, Port Jefferson Station, Rocky Point, Yaphank and Patchogue. That brings the total in Suffolk so far this year to 179.

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Residents are advised to eliminate stagnant water where mosquitoes breed around their homes; to minimize outdoor activities and cover skin in the evening and night when mosquitoes are most active; and to use mosquito repellent outdoors.

Last year, 2,205 West Nile cases in humans were reported in the United States, resulting in 97 deaths, according to the federal Centers for Disease Control and Prevention.

Nassau had four reported human cases of West Nile last year, while Suffolk reported one case. There were no deaths last year in either county.