The list of municipalities in Schuylkill County that have positive test results for the West Nile virus keeps growing.
Tamaqua Borough and West Mahanoy Township mosquitoes tested positive for the virus Aug. 13, the state Department of Environmental Protection said, joining Minersville and Cressona boroughs, and Butler, Pine Grove and Tremont townships.
Last year, 10 municipalities had mosquitoes that tested positive for the virus. June 19 was the first time in the county the virus was reported last year. This year, that date was July 26.
No human cases have been reported in Schuylkill County.
The state Department of Health said Friday that the first probable human cases of the virus had been detected. They include a man from Montgomery County who was hospitalized and a man from York County who did not need hospitalization. They were reported Tuesday and are listed on the state website www.westnile,state,pa.us.
Countywide, there are 13 positive cases of the virus, the website says.
"We've done 18 mosquito control events (9 of which were in the last two weeks, after the last round of samples found more infectivity) in Schuylkill County," said Amanda Witman, DEP spokeswoman, by email Tuesday. "The next round of sampling will focus on residential areas in the areas displaying the highest level of infectivity. Control decisions will be made after the results of that sampling is done."
So far, 500 cases of the virus have been documented statewide.
In 2012, 3,656 cases of the virus were detected. Sixty human cases of the virus were reported in the state and four people died.
The first reported case of the virus in the state this year was in Harbor Creek Township, Erie County, on May 22.
So far, 38 of the 67 counties in the state have had positive results for the virus detected in mosquitoes. Six counties have had birds test positive for the virus.
Delaware County has the most reported cases of the virus at 58; Adams County has 45 cases; Bucks County, 40; York County, 38; and Schuylkill has 13.
"The localized nature of the virus is very typical," Witman said in an email. "The epidemic we saw last year was quite unusual. There are many variables that impact the amount of the virus detected in the mosquito population. Chief among those variables is the weather. We haven't had a very hot summer, and the virus likes the heat. Also, mosquitoes came out much later this year because of a cool spring, which gave the virus less time to amplify, as opposed to last year's early emergence."
The county is now classified as having a "moderate risk" for having the virus, according to the state. Bucks and Montgomery counties are rated at "high risk," state data shows.
The virus is most often spread by mosquitoes but also through blood transfusions, organ transplants, breast feeding and during pregnancy, the Centers for Disease Control and Prevention said on a fact sheet.
The virus causes flu-like symptoms and can result in encephalitis, an inflammation of the brain. Those infected can show symptoms in three to 14 days after being bitten by a mosquito.
No cases of West Nile were found in the United States before 1999 and it was first detected in Pennsylvania in 2000. It is named after the area in Uganda where it first appeared in 1937, according to the West Nile virus website.