BATON ROUGE, La. -- Even people who hate thunder and lightning can appreciate one effect of the storms that have pummeled south Louisiana almost daily in recent weeks: there aren't many mosquitoes.

That has contributed to another excellent lack.

"We have no West Nile virus cases this year. It's very unusual," said Dr. Raoult Ratard, the state epidemiologist. "Usually the first cases are sometime at the beginning of July, and usually by the middle of July we have a few.

"Here we are in the beginning of August, and not a single human case."

Blood tests have turned up a few West Nile infections in Louisiana, but the type of antibodies indicated that they were people who developed immunity after bites last year or earlier, Ratard said.

Rain usually creates breeding spots for house mosquitoes, which lay eggs in stagnant water -- anything from mostly dry drainage ditches to flowerpot saucers -- and for floodwater mosquitoes, which prefer fresh water.

But mosquito control officials across South Louisiana say downpours last month and so far this month were so frequent and heavy that they washed eggs and larvae into bayous, swamps and lakes, where they became fish food.

It's an especially refreshing change after a year in which areas opened up by Hurricanes Katrina and Rita in 2005 bred record swarms of the pests, said Lucas Terracina, director of mosquito control for Calcasieu Parish.

"I've been here 31 years and I've never seen mosquitoes consistently like we had last year," Terracina said. He said it's common for large swarms to hatch after big storms -- "major breakouts of mosquitoes that make you want to pull your hair out. But as many mosquitoes as we had from January through October was just unprecedented."

The cool winter and dry spring were a big help, too, Terracina said. He didn't have numbers for comparison in his parish, but Dennis Wallette, director of the Tangiphoa Mosquito Abatement District north of Lake Pontchartrain, did.

Traps that regularly caught thousands of mosquitoes a night last year -- and some that caught more than 20,000 a night after a huge hatching of salt marsh mosquitoes toward the end of the year -- are collecting fewer than 100 a night, he said.

"Some of this is due to the weather. A lot is because we've been seeing some of this activity and we've been attacking them very hard," he said. Trucks spray larvicide into roadside ditches, people with pump sprayers hit the standing water, and trucks spray the air at night for adult mosquitoes.

In northeast Louisiana numbers appear to be about average, said Cole Church, director of the Ouachita Parish Mosquito Abatement District. Northwest Louisiana, on the other hand, has more than usual, the result of a wet summer after four years of drought, said Bryan Glascock, biologist for Caddo Parish Mosquito Control. Rains in the area haven't been heavy enough to wash away eggs.

In the south, the drop in numbers is as obvious to people who aren't looking for mosquitoes as it is to people who make mosquitoes their profession.

"You expect to go out there and get bit by mosquitoes, and you don't," said Earl Higgins, whose job as a ranger at the Jean Lafitte National Park and Historic Preserve near Marrero includes walking miles of trails along swamp and marshland.

Usually, he said, he'd be spraying repellent on himself and selling it to visitors. But not this year.

Still, doctors and mosquito control experts warn that people should wear long sleeves and pants at dawn and dusk and use mosquito repellent.

"We don't want people to let their guard down," Wallette said.

By the end of July, Mississippi had reported 13 human cases of West Nile Virus to the federal Centers for Disease Control and Prevention. Texas had reported six and Arkansas one. Nationwide, 185 cases have been reported.

(Copyright 2007 by The Associated Press. All Rights Reserved.)