So far this year, no human cases of West Nile have been reported in New Jersey, but mosquitoes in 19 counties have tested positive for the virus.

That's pushing officials to ramp up control efforts.

In Bergen County, the Bergen Bites Back program is looking to limit the risk with surveillance, spraying, and even mosquito-eating minnows.

Senior correspondent Brenda Flanagan takes us behind the scenes and explains why the peak risk is still to come.

So these are mostly Culex mosquitoes.

A behind-the-scenes look at Bergen County's mosquito-fighting arsenal turned up surveillance traps called pools.

This one's baited with fermented water and grass, says expert Matt Bickerton.

So it has a certain type of odor.

It's what we call stink water.

Turns out stink water's irresistible to Culex mosquitoes, making it easy to trap and check them for West Nile virus.

This trap uses the smell of human sweat to lure Asian tiger mosquitoes, another West Nile vector.

Lab tests of these so-called mosquito pool samples in Bergen reveal a potential problem.

For the last couple weeks, we have--almost all the mosquitoes we tested were positive for West Nile.

It's above average.

It's kind of in line with where things were at last year.

And last year, we had quite a few people that got sick from West Nile virus.

Because we've had such a high positive pool tests, we believe that we want to be out in front of this to prevent somebody from getting the disease.

Pools like these get tested weekly across the state.

Out of more than 5,000 mosquito pools tested in New Jersey, 384 so far this season have revealed positive evidence of West Nile virus in 19 of 21 counties.

Mosquitoes like warm, wet weather, and they breed in standing water in amounts as small as a bottle cap full.

This is a hot zone, you know.

In Bergen County, Hudson County, Union County tend to be relatively high for West Nile.

We think that's mostly because the mosquitoes that are the best vectors for West Nile virus are urban--they're urban species.

These larvae mature in about a week.

The females can live and bite for a month, laying multiple egg batches.

To attack the hatchlings, the county's $2 million Bergen Bites Back program sprays residential neighborhoods with VectoBac, a biological larvicide, usually over housetops and into yards during pre-dawn hours.

You've got to be proactive in some fashion.

So I think part of it is an education process, explaining to folks the trade-offs, right?

And we are using the safest products that are on the market.

Bergen residents can also call the county and ask to have their yards individually sprayed for free.

Folks are urged to clean pools and dump standing water, even birdbaths.

The county also deploys special minnows that devour the larvae, called wigglers, in ponds and lakes.

Meanwhile, global warming only helps extend the Culex mosquitoes' breeding season, Bickerton figures.

We had an early West Nile positive.

That was May 21st.

So that was really unusual.

We haven't had activity that early in recent memory.

Last year, New Jersey reported 41 human cases of West Nile in 14 counties with 8 deaths from complications, compared to 13 cases and 1 death across 7 counties in 2023.

But most people bitten by infected mosquitoes don't even know it.

Most people probably who get infected with West Nile have no symptoms.

So that's the positive.

The issue is with certain people, especially immunocompromised and elderly, it's fatal.

It could be fatal.

Mosquitoes carry other diseases, too, including dengue fever, malaria and chikungunya.

New Jersey's West Nile season peaks between mid-August and mid-September.

In Paramus, I'm Brenda Flanagan, NJ Spotlight News.

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