The West Nile virus season isn't over yet.
The number of human cases in North Texas is expected to rise in September, following a rapid increase in the number of mosquito traps that test positive for West Nile.
But most people will never know they even have it, health officials say.
"We could literally be experiencing an outbreak this season, and very few people are actually coming down with symptoms of the illness," said Patrick Prather, with Municipal Mosquito in Richardson.
In fact, few people infected by West Nile show any symptoms, and the Centers for Disease Control and Prevention says no one bitten by the virus should ever get it again.
Without even knowing it, many North Texans may already be immune.
"Eighty percent of the individuals who are bitten show no signs," said Zachary Thompson, director of Dallas County Health and Human Services. "So therefore, we probably have built immunity in Dallas, Texas, and the North Texas area."
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A simple blood test can spot the signs of a past infection, and with it, a natural immunity to the virus.
"You determine if the antibody is in the system, whether it's a little amount or a big amount. It will come back with a distinct number," said Jennifer Wallace, with Any Lab Test Now, which offers the West Nile blood test.
But don't put away the mosquito repellent.
Although the CDC thinks the natural immunity could last a lifetime, it could begin to fade after a few years.
