(CBS News) Reports of mosquitoes with West Nile virus are popping up all over the country, with several people already confirmed to be infected by the potentially dangerous disease.
West Nile virus is spread from the bite of an infected mosquito, which gets the disease when they feed off infected birds. The mosquitoes then transmit the disease to other animals or humans.
Symptoms can range in severity: Milder symptoms may last from a couple days to several weeks and may include fever, headache, muscle aches, rash, nausea and vomiting. Severe symptoms may affect one in 150 people with the disease, and include high fever, headache, neck stiffness, disorientation, coma, tremors, vision loss, paralysis and other neurological effects that may last several weeks or become permanent. Up to 80 percent of people infected with West Nile won't show any symptoms, according to the Centers for Disease Control and Prevention.
CBS local affiliate KPHO in Phoenix reported on Wednesday that a woman in her 30s was diagnosed with West Nile virus which led to the brain infection meningitis. Local officials warned the heat combined with the beginning of monsoon season provide ripe conditions for the disease.
Many minor cases of West Nile go unreported as most people who get the virus only feel sick for a day or two, but never require a doctor's visit, Dr. Bob England, director of Maricopa County Department of Public Health in Arizona, told the station.
CBS Dallas Fort Worth reported last week of a confirmed case of West Nile in a human in Tarrant county, Texas, only a day after a case was confirmed in Richardson, Texas. Earlier in the month another Texas case was reported, this time in Denton County, which prompted a warning from North Texas Health Officials that the illness may spread quickly, KTVT in Dallas reported.
In New Orleans, officials said Thursday they detected West Nile in mosquitoes collected in the city. No human cases have been confirmed in New Orleans, but the local Mosquito and Termite Control Board will increase spraying, CBS affiliate KLFY in Lafayette, La., reported. A human case of West Nile was reported in nearby St. Bernard Parish.
The Washington Post reported Tuesday that mosquitoes found in Prince William and Fairfax counties, Virginia have tested positive for the virus.
"Typically, we don't start seeing cases until early July," David Gaines, a public-health entomologist with the Virginia Department of Health, told the paper.
In Boston, state health officials said Thursday that mosquitoes tested positive for the virus for the first time this summer, but no humans have tested positive for the virus. According to CBS Boston, The Boston Public Health Commission also said recent hot weather and rain may have contributed to the virus' slightly earlier appearance.
Connecticut mosquito experts warned Thursday that the number of mosquitoes that typically carry West Nile has doubled in the past week, evidenced by traps that are set up statewide, according to the Associated Press. Officials said many of the mosquitoes may have survived the mild winter, and were brought out by recent rains and hot weather. There have been no reports of the disease in the state.
Florida officials are also expecting an uptick in mosquitoes following Tropical Storm Debby, the AP reports.
"We are definitely within 10 days from now going to have a plethora of mosquitoes," said Conlon, a retired Navy entomologist, adding that the mosquito breeding cycle is usually seven to 10 days.
The simplest way to prevent contracting West Nile virus is to prevent mosquito bites. The CDC recommends using an insect repellant containing an EPA-registered active ingredient (such as DEET or Picaridin), especially at dusk and dawn when mosquitoes are most active. People should also consider wearing long sleeves and pants or stay indoors during these times. Mosquitoes typically breed in standing water pools, so empty flower pots, buckets and barrels and frequently change the water in pet dishes or bird baths. Also, make sure you have good screens on windows and doors to keep mosquitoes out.
The CDC has more on West Nile Virus.