MANDEVILLE, La.–As dusk fell on St. Tammany Parish, Sam Costanza cast a line for croaker from the banks of Lake Pontchartrain–and counted on an occasional breeze to keep the mosquitoes at bay.

“You can’t tell which mosquitoes are infected with West Nile,” he said, flicking away the bugs that hovered near his bare arms. “But you can’t run away from them, either. When you’re around mosquitoes as much as we are, you learn to take your chances.”

But as an insect-borne epidemic worsens, the nonchalance of residents such as Costanza has health officials on edge. A 76-year-old woman became the fifth Louisiana resident to die of West Nile virus, the state’s epidemiologist said Tuesday, and 14 more people have fallen ill across the state.

The fresh cases bring Louisiana’s sick toll to 71, and make this the worst outbreak of West Nile since the disease came to the United States three years ago. This summer, the southern rite of bug bites can be a deadly affliction–and the virus shows no sign of abating.

“This is only the beginning,” Louisiana epidemiologist Raoult Ratard said. “It won’t be surprising if we get 200 or 300 cases before it’s over.”

Mississippi has confirmed 22 cases of West Nile virus this year. Texas health officials suspect they have had 10 residents fall ill with the virus. And earlier this week, another suspected West Nile victim turned up in Arkansas, near the Louisiana border.

East Baton Rouge Parish has lost two people to the disease. A resident of Calcasieu Parish, near the Texas border, died of West Nile virus. Here in St. Tammany Parish, across the watery stretch of Lake Pontchartrain from New Orleans, two people have died, and 18 more were infected.

Even 8-year-old Jocelyn Rojas knows those numbers by heart–along with the warning that this year’s mosquitoes “have a disease.” Before she and her brothers step into the afternoon to walk the family dog along their heavily wooded street, they slather every inch of exposed skin with insect repellent. Nevertheless, the kids end up swatting bugs from their legs.

“You protect yourself with bug spray as best you can,” said their 36-year-old father, Eric Rojas. “We don’t stay out very long, just long enough to get in a short walk after work. When we go back to the house, we won’t come out until morning. We don’t take unnecessary risks, but you have to live your life.”

When darkness falls, the mosquito trucks come rumbling through the streets, yellow lights flashing, to spray a fine mist of pesticides over the lawns. From dusk to midnight, low flying planes blanket the 910-square mile parish with bug poison.

“Oh, it stinks,” said Jennifer Bonnell, 26. “You hate to think what’s in the stuff. But I think it’s working. I’m not noticing as many mosquitoes out there.”

At its worst, West Nile can bring on encephalitis, a fatal swelling of the brain. Most of the victims killed in Louisiana were elderly people whose immune systems were weakened by other health problems, said Charlie Anderson, Louisiana’s West Nile virus coordinator.

But more often than not, the virus is a relatively mild malady. Most of those stricken with West Nile don’t get sick, or suffer flu-like symptoms. The improbability of a serious infection has fueled a cavalier outlook among many residents, said Dawn Wesson, a mosquito specialist at Tulane University Health Sciences Center in New Orleans.

“There’s the attitude that we’ve always had mosquitoes and they’re not going to make me sick anyway,” she said. “But you wouldn’t want to be the one who gets sick. It’s not worth the gamble.”

Louisiana’s West Nile epidemic is most likely a function of its geography. This swamp state of lush greenery and stagnant waters makes for a buggy pit stop in the path of migrating birds. The virus is carried from one state to the next by birds, then transmitted by mosquitoes.

“Some of the things that make our state so beautiful also supports mosquito development,” Wesson said.