The Consolidated Mosquito Abatement District collected positive adult mosquitoes in the 93727 zip code.
It is urging people to report neglected swimming pools - because they can be a major source of mosquito production.
The best way to protect yourself from mosquito bites is by practicing the three Ds.
Deter - by applying insect repellent.
Drain standing water.
And remember mosquitoes are most active at Dawn and Dusk.
"We're very concerned with mosquitoes that are active during dusk and dawn, and we did collect our first conflict mosquito sample in the city of Fresno, in an area south of Belmont between Clovis Avenue and Fowler Avenue. So, at this point we will be doing a ULV treatment," said Kathy Ramirez with the Consolidated Mosquito Abatement District.
The district says West Nile is typically detected at the end of May or early June - and continues through the summer months.