This summer's mosquitoes brought more than pesky buzzing and bites. About 1,600 cases of West Nile virus have been reported nationwide, more than four times the typical level and one of the worst outbreaks ever. Insecticides are being sprayed from trucks and planes to combat the virus-carrying mosquitoes, which get West Nile from infected birds. Texas is particularly hard-hit, with officials reporting more than 700 infections and at least 31 deaths. The mayor of Dallas approved aerial spraying for the first time since 1966.

The virus may cause weeks of disorientation, vision loss and even temporary paralysis. In extreme cases, nerve damage can be permanent. There's no vaccine to prevent the virus and no medicine to cure it.

Health officials are unsure why this outbreak is worse than earlier ones. Personal precautions include wearing long sleeves and pants, staying inside at dawn and dusk when insects are active, putting insect repellent on bare skin and eliminating mosquito-breeding areas such as bird baths, wading pools or other standing water.

Federal doctor says: "The number of West Nile disease cases in people has risen dramatically. We are in the midst of one of the largest West Nile outbreaks ever seen." – Dr. Lyle Petersen, Centers for Disease Control

State official says: "I have my own can of Deep Woods OFF that I'm pretty religious about putting on. Preventive measures are the key thing." -- Kimberly Mitchell, Maryland Department of Health

Professor says: "The benefits of these [aerial] sprays far, far outweigh the risk. The materials they are using are the same pesticides you would use to spray the vegetables in the garden or some of the pests that invade your home. These are relatively safe materials." -- Mike Raupp, University of Maryland College of Agriculture