NJ's first case of West Nile virus confirmed; more mosquitoes test positive

• West Nile virus in mosquitoes is up sharply from a year ago.
• Bergen County has had the most cases so far in 2018.
• The first human case of West Nile was recently reported and two suspected cases are under review.
• In Warren County an Asian Tiger Mosquito -- known as a people biter -- was found to be carrying West Nile.

The first case of human West Nile virus has been confirmed in New Jersey, which is also seeing a sharp rise of mosquitoes that carry the infection. 

The rise of West Nile virus-carrying mosquitoes reported so far this summer will be exacerbated, experts anticipate, by the recent heavy rains and floods.

The most recent surveillance report available from July 29 to Aug. 4, shows 284 mosquito pools in 20 counties tested positive for West Nile Virus. This is 48 percent higher than last year at this time.

Residents across the state are urged to help eliminate mosquito breeding areas and to use repellent to guard from potential infection.

The first human case of West Nile virus for 2018 was reported last week in a 74-year-old Hunterdon County man, and there are currently two other suspected cases under investigation. 

Last year eight individuals in the state were diagnosed with West Nile virus, according to the New Jersey Department of Health.

The data shows that in Bergen County seven pools tested positive for West Nile bringing the total for the year to 57. Bergen is the county with the highest number of positive tests for West Nile in 2018 so far. Somerset was next with 25. For the year Morris County has had 19 cases, Passaic none, Essex four, and Sussex two.

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An expert with the Warren County Mosquito Commission said the recent rains and flooding will make an already tough mosquitoes summer even worse. 

"It's a really bad year statewide," said Jennifer Gruener, superintendent of the Warren County Mosquito Control Commission.

"With this flooding the mosquito populations are out of control," she said. "It's just really hard to keep up with the timing and the amount of rains we've gotten. Especially this last rain."

Twelve samples of mosquitoes tested positive for West Nile virus in Warren County during the last count, leading to control spraying in several towns.

Gruener said to expect more mosquitoes in areas like Little Falls where flooding occurred Saturday. The almost 5 inches of rain that fell in 50 minutes swept SUVs from a car dealership down a river, which created an artificial dam under the Route 46 highway overpass.

"That's going to take just an enormous amount of effort to try to control the mosquitoes that come out of that amount of flooding," she said.

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The 12 samples that tested positive for West Nile last week in Warren were collected from Franklin Township, Phillipsburg, Oxford Township, Belvidere, White Township, Washington Township, and Hackettstown, Gruener said. 

She said that most of the samples were Culex mosquitoes, primarily a bird-biting mosquito. However, the positive sample from Phillipsburg was Aedes albopictus, the Asian Tiger Mosquito, she said.

"It's really a nasty mosquito," Gruener said. "It carries a lot of potential for different diseases."

Asian Tiger mosquitoes can transmit the Zika virus, Dengue and Yellow fever. It's an invasive mosquito that will bite people during the day, she said.  

"It doesn't really bite as many animals, mammals and birds as some of the other mosquitoes," Gruener said. "That raises a little bit more concern when it starts to get into the species that are more apt to bite people." 

Gruener said the Asian Tiger mosquito made its way into Warren County in 2012 and is slowly moving north. For several years it was contained to the Phillipsburg area until last year they invaded Oxford and then Independence this year.

"So it really, really expanded its range this year," she said.

Gruener said it's likely that tires containing disease-ridden eggs made their way to a local landfill in Oxford and to a junk yard in Independence.

So far this year, a total of 26 samples of mosquitoes have tested positive in Warren County from 11 different towns. The average number of positive mosquito samples in Warren County is between eight and nine per year. Mid to late August is peak time for humans and other mammals to acquire this virus.

The mosquito commission continuously traps at a rotation of sites and will go to different areas if they receive complaints. After an unusual number of dead crows were spotted in Hackettstown the commission did testing there.

"It's just a really active year this year," Gruener said. 

West Nile Virus is really primarily a bird virus so it circulates between mosquitoes and birds, and as the season goes on it amplifies, she explained. 

"We call that the amplification cycle where more and more mosquitoes get infected and more and more birds get infected," she said. "...Then other mosquito species start to feed on the birds and pick up the virus."

The mosquito control commission recommended the following precautions to help reduce the risk of contracting mosquito-born diseases: 

• Use repellents containing DEET, Picaridin, or Oil of Lemon Eucalyptus.
• Avoid being outdoors when mosquitoes are present, typically dawn and dusk.
• Don't produce mosquitoes on your property. 
• Dump or drain standing water every couple days.
• Mosquitoes can't begin their life without water.
• In Warren County neglected swimming pools should be reported. Call 908-453-3585, or visit warrencountymosquito.org.

Gruener said that some mosquitoes can go from egg to adult in as little as four to five days. 

"So they really need to be vigilant," she said. "We can't go to everybody's backyard and dump out their buckets, tires, plant saucers. We just can't get there. Tarps are a big one. [In] 90 percent of the yards we go to people are producing mosquitoes. They don't even realize it."

Follow Jai Agnish on Twitter: @Jai Agnish. Email: agnish@northjersey.com.