Mosquitoes carrying a virus that causes paralysis and death are becoming immune to common bug sprays

• Mosquitos that transmit the West Nile virus are immune to some bug sprays, and even live longer after exposure.
• Although rare, West Nile virus can cause severe illness or death.

Extreme hot weather coupled with heavy storms this year has created the ideal conditions for mosquitoes, including the infamous Culex mosquito — which transmits West Nile virus.

On top of an already brutal mosquito season, community insecticides — a first line of defense against Culex mosquitoes — seem to be less effective at killing the bugs and their eggs.

Not only are mosquitos unfazed by the insecticide, they actually seem to be fortified by it: those exposed are living longer, according to researcher Roxanne Connelly who works as a medical entomologist at the Centers for Disease Control and Prevention.

"You want a product that's gonna be able to knock them down, not do this," Connelly told NBC News.

This combination of events has caused concern for researchers, who urge the public to be extra vigilant of West Nile virus and to protect themselves from bloodthirsty mosquitoes.

Most people who get West Nile virus don't feel sick, but for some it can cause permanent disability or death

West Nile virus is the most common mosquito-borne disease in the US.

As of August 1, there have been 90 cases of West Nile virus recorded in a total of 17 states, according to the CDC. But this number is expected to grow.

"This is just the beginning of when we see West Nile start to take off in the United States," Dr. Erin Staples, a medical epidemiologist at the CDC's Fort Collins lab, reported to NBC News. "We expect a steady increase of disease to occur over the next several weeks."

The vast majority of people who are infected by West Nile don't feel sick. However, one in five people will experience symptoms, which can include a fever, headache, body aches, vomiting and diarrhea according to the CDC.

Only one in 150 people develop serious complications, including neurological symptoms like headache, stiff neck, convulsions, vision loss, paralysis, coma or even death.

There is no cure or treatment for West Nile virus. Those at greatest risk of serious illness are people over the age of 60 and those who have underlying medical problems.

5 things you can do to prevent mosquito bites

It's not clear to scientists why the Culex mosquito is becoming resistant to community based insecticides — which are sprayed liberally by farmers to protect produce, landscapers to avoid nuisance, and by vector control workers to prevent disease spread, reports Vox. But you can still protect yourself from mosquito bites.

Bug sprays with DEET and picaridin are still highly effective at fending off hungry mosquitos, according to the CDC.

They also recommend wearing loose-fitting clothing that covers the arms and legs, screening open windows and doors to prevent mosquitoes from coming inside, and using air conditioning when possible.

Regularly emptying standing water around your yard — including from bird baths, flower pots and toys — can prevent mosquitoes from reproducing.