In the time it took him to walk down his driveway in Fort Collins, Colorado, chat briefly with a neighbor and return to his house, Petersen got infected with a potentially serious mosquito-borne illness called West Nile virus.

CNN: CDC expert gets West Nile bug -- literally

The water is also an excellent breeding ground for mosquitoes, particularly in the warm, wet climate of the Gulf Coast, which could mean a spike in mosquito-borne illnesses such as West Nile virus.

ECONOMIST: The fallout from Katrina | The