States across US are seeing seasonal increase in mosquitoes with West Nile virus

Several health departments in the U.S. say they have detected West Nile virus in mosquito samples.

Although the average number of actual West Nile cases is significantly lower than the same time last year, experts are urging the public to take precautions.

On Monday, the Cape May County Health Department in southern New Jersey sent out a press release reporting that seven mosquito collections during the months of June and July had tested positive for West Nile virus.

Denton County Public Health in Texas also reported on Monday that five positive West Nile virus mosquito traps had been collected in unincorporated Denton County, with health officials saying the locations would be fogged for treatment.

In Suffolk County, New York, the health department announced on Monday that 16 mosquito samples have tested positive for West Nile virus, bringing the total to 32 so far this season. Meanwhile, data from the New York City Department of Health and Mental Hygiene shows West Nile-positive mosquitoes have been detected in all five boroughs.

"The confirmation of West Nile virus in mosquito samples indicates the presence of West Nile virus in the area," Suffolk County Health Commissioner Dr. Gregson Pigott said in a press release. "While there is no cause for alarm, we advise residents to cooperate with us in our efforts to reduce exposure to West Nile virus and other mosquito-borne diseases."

So far, only 25 cases of West Nile virus have been reported in 14 states, according to data from the Centers for Disease Control and Prevention. This is lower than the 117 cases reported at the same time last year.

West Nile virus is the leading cause of mosquito-borne disease in the contiguous United States, according to the CDC. It was first introduced in the Western Hemisphere during the summer of 1999 after people were diagnosed in New York City.

Mosquitoes typically become infected with the virus after feeding on infected birds and then spread it to humans and other animals, the federal health agency said. Cases typically begin rising in July and are highest in August and September, CDC data shows.

The majority of people with the virus do not have symptoms, but about one in five will experience fever along with headaches, body aches, joint pain, diarrhea, vomiting or a rash. Most symptoms disappear but weakness and fatigue may last for weeks or months.

About one in 150 will develop severe disease leading to encephalitis, which is inflammation of the brain, or meningitis, which is inflammation of the membranes that surround the brain and spinal cord -- both of which can lead to death. So far this year, 11 of the 25 cases have resulted in neuroinvasive disease, according to the CDC.

There are currently no vaccines or specific treatments available for West Nile virus. The CDC recommends rest, fluids and over-the-counter medications. For those with severe illness, patients often need to be hospitalized and receive support treatments such as intravenous fluids.

To best protect yourself, the CDC suggests using insect repellant, wearing long-sleeved shirts and pants, treating clothing and gear and taking steps to control mosquitoes. This last step includes putting screens on windows and doors, using air conditioning and emptying out containers with still water.