Health officials remind residents to take precautions against mosquito-borne West Nile virus, an annual summer occurrence across Louisiana.

"So far, we have not received positive samples from Terrebonne or Lafourche, but there are seven parishes who have already gotten some positive samples for the virus," said Steve Pavlovich, entomologist with Mosquito Control Services.

The company contracts with both parishes to spray chemicals to kill mosquitoes and test for the diseases they carry.

About eight of 10 Americans who contract West Nile never show symptoms, according to the U.S. Centers for Disease Control and Prevention. One in five people develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea or rash. Most recover completely, but fatigue and weakness can last for weeks.

One in 150 people who are infected develop a severe illness affecting the central nervous system, such as inflammation of the brain, the agency says. The disease has no cure, and doctors treat the symptoms in severe cases.

"People can experience symptoms like encephalitis, high fever, disorientation, numbness and, in some cases, death," said Dr. Frank Welch, medical director for Community Preparedness at the Louisiana Health Department. 

State Health Department statistics show a different story than nationally. In the past five years, the state received reports of 368 people infected with West Nile. Out of that number, 52 cases showed no symptoms, 114 high fever, 202 developed brain swelling and 20 resulted in death.

During that same time frame, at least two local residents have died from West Nile. In 2014, the deaths of an 88-year-old man from Thibodaux and an 82-year-old man from Larose were attributed to the illness.

However, the number of cases serious enough to be reported to the state Health Department has not exceeded half a dozen in either Terrebonne or Lafourche over the past five years, records show.

Both parishes work year-round to protect residents against mosquitoes, Pavlovich said.

"We operate all year, but we are more active now due to the higher population of mosquitoes that come with the summer season," he said. "We use several devices that help us monitor where mosquitoes are growing and which type of mosquitoes those are."

The primary type that transmits West Nile in Louisiana is the Southern house mosquito, whose population typically peeks in August, September and October.

"We do a lot of surveillance for those particular mosquitoes," Pavlovich said.

Mosquito Control sends potentially infected mosquitoes to the LSU Diagnostic Lab. Both parishes issue public notices when mosquitoes test positive locally so residents can take precautions.

-- Staff Writer Andrea Mujica can be reached at 850-1148 or Follow her on twitter @CationM.