NYC officials said there is in increase in mosquitoes with West Nile virus this summer.
The New York City Health Department says the virus has been detected in "nearly twice as many mosquito pools as this time last year," and is stepping up control efforts across the city.
West Nile virus typically spreads through infected mosquitoes who bite humans. The virus is seen during mosquito season, which takes place from summer to fall, or June to October.
Late August is when the virus usually peaks, according to the Centers for Disease Control and Prevention.
Those who contract the virus usually see symptoms two to six days after a bite, the agency says. Common symptoms include fever, headaches, body aches, joint pain, rash, vomiting and diarrhea, according to the CDC.
Most, however, do not develop symptoms at all.
Although no human cases have been reported in the city this season as of Aug. 6, the health department warned New Yorkers to take additional precautions to stop mosquito bites after seeing an increase of the virus in mosquito pools.
"Each week, trained staff collect mosquitoes from hundreds of locations across the city," the agency said in a release. "The mosquitoes are grouped into samples, or 'pools,' with up to 50 mosquitoes tested together for the presence of West Nile virus."
Out of over 2,000 pools tested, 612 came back positive. Last year, 326 pools tested positive.
The city has a map for New Yorkers to see where West Nile virus has been detected here.
"The Health Department has intensified mosquito surveillance in affected areas by deploying additional traps and expanding mosquito control efforts," the agency wrote. "Enhanced larval control is also underway to reduce mosquito populations before they become capable of transmitting disease."
Alongside testing mosquitoes weekly, NYC Health has other methods to decrease the mosquito population, including:
Dropping larvicide via helicopter over nonresidential spots like marshes, wetlands and more
Spraying via truck for adult mosquitoes in select neighborhoods (residents are made aware of treatment at least one day in advance)
A schedule of efforts planned can be found here.
Limiting outdoor time during dawn and dusk
Wear clothing that covers, such as long sleeves and pants while outdoors in areas with activity of mosquitoes
This article originally appeared on USA TODAY: NYC officials see increase in West Nile virus mosquitoes. What to know