Washington, DC (written by Elizabeth Weise/USA Today) -- West Nile virus cases nationally were up 40% from last week, now totaling 1,590, including 66 deaths, the Centers for Disease Control and Prevention said Wednesday.
The CDC repeated its warning that this year may have the highest number of cases since the virus was first found here in 1999.
"We think the numbers may come close to or even exceed the total reported in 2002 and 2003," both of which were severe West Nile virus years, said Lyle Petersen, director of the CDC's Division of Vector-Borne Infectious Diseases.
More than 260 deaths were reported each of those years.
The case count in 2012 is the highest number of West Nile virus disease cases reported through the last week in August ever. Health officials expect the mosquito-borne disease to continue to peak into September and early October, Petersen said.
More than 70% of the cases have been reported from six states: Texas, South Dakota, Mississippi, Oklahoma, Louisiana, and Michigan. Forty-five percent were in Texas.
David Lakey, commissioner of Texas' Department of State Health Services, said the state had 783 confirmed cases and 31 deaths as of Tuesday.
Hurricane Isaac is not expected to have a big effect on West Nile virus cases, Petersen said. There can be a transitory bump in cases soon after a big storm simply because so many people are outside working, but this doesn't generally result in a large increase in illnesses, he said.
That's because hurricanes and floods tend to disrupt the entire ecology of an area, interrupting the transmission of the virus between birds and mosquitoes. Hurricanes also flush out ponds, pools and puddles, decreasing the number of mosquitoes.
However, health officials did warn the public to take care over the coming three-day Labor Day weekend with its backyard barbecues and other outdoor events.
Lakey offered up the "Four D's" for West Nile defense:
•Use DEET mosquito repellants.
•Dress in long sleeves and pants.
•Stay indoors at dusk and dawn.
•Drain standing water where mosquitoes breed.
Most people infected with West Nile virus will not have any signs of illness, but 20% will experience mild symptoms such as fever, headache, body aches and in some cases a skin rash on the trunk of the body and swollen lymph glands.
People older than 50 and those with compromised immune systems are most at risk.
About one in 150 people will get more severe symptoms: headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis.