FULLERTON (CBSLA) – Due to an increase in West Nile Virus activity, several Fullerton neighborhoods will be sprayed with pesticides this week.

The Orange County Mosquito and Vector Control District reported Tuesday that two people have recently tested positive for West Nile Virus in the Fullerton area, along with 29 mosquito samples which have also tested positive.

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Officials have not been able to pinpoint a specific reason for the increase in the West Nile virus activity.

“It could be a number of small backyard sources contributing to that,” said Lora Young with OCMVCD.

This has prompted OCMVCD to spray two areas with a pesticide known as DeltaGard, a water-based mosquito control product. Those areas contain nearly 4,000 properties, the district reported.

The spraying will take place on Thursday through Saturday between the hours of 2 a.m. and 5 a.m.

The pesticide is not harmful to people or pets, the district said. It will also not cause any damage to the finishes on cars or homes.

It’s the district’s first time using DeltaGard, according to Young. It is considered safe for people, pets and will not harm the finishes on cars or homes.

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DeltaGard has gone through several regulatory checks by the federal Environmental Protection Agency to the state EPA and the county’s agricultural department, Young said.

“We’re accountable to the county agricultural department to report usage and to comply with label rates and safety standards,” she said.

Symptoms of the virus — which is transmitted by mosquito bites — can include fever, body aches, rash, nausea, vomiting and headaches, but many people who are infected may not show any symptoms. About one in 150 people could develop more serious problems, such as brain inflammation or paralysis, health officials said.

To protect yourself from WNV, wear mosquito repellant containing the active ingredients of DEET, Picaridin or IR3535 if you are spending time outdoors.

You should also replace any standing water around your home, such as pet bowls, at least once a week, because those can serve as a mosquito breeding ground. You should also close all unscreened doors and windows to prevent mosquitoes from entering your home.

For more information on WNV and the Fullerton spray schedule, click here.

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(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)