(CBS News) The worst West Nile virus outbreak the country has ever seen remains on the rise, the Centers for Disease and Prevention said Wednesday.
In a press conference with reporters, the CDC said there are a total of 1,590 reported cases of West Nile virus in the United States. That's a 40 percent rise from last week's cases. There have also been 66 deaths reported.
The CDC said the disease has been seen in mosquitoes, birds or people in 48 states - up from 47 last week - with the only exceptions being Alaska and Hawaii. Forty-three states have reported at least one human case, up from 38 last week.
Of the reported cases, 56 percent - or 889 - were classified as neuroinvasive disease 44 percent (701 cases) were classified as non-neuroinvasive disease. Similar to last week's West Nile briefing, the CDC said these are the most reported cases of West Nile through this point in August since the virus was first detected in the U.S. in 1999.
Dr. Lyle R. Petersen, director of the division of vector-borne infectious diseases at the CDC said the rise was not unexpected. "In fact we think the reported numbers will get higher through October"
Peterson said at this rate the outbreak may exceed the U.S. West Nile epidemics from 2002-2003, when 3,000 cases of the disease and 260 deaths were reported each of those years. The current outbreak is expected to peak in late August, the CDC said.
Last Wednesday, the CDC reported an alarming rise in West Nile virus cases, finding 1,118 cases of the disease across 38 states, including 41 deaths (629 or 56 percent, were classified as neuroinvasive disease). The month before, there were only 25 reported cases in the country.
The CDC said today that 45 percent of the country's cases have been reported from Texas.
Dr. David L. Lakey, commissioner of the Texas Department of State Health Services, told reporters at today's briefing that his state has seen 783 confirmed cases, up about 200 from last week, and 31 deaths. More than 400 of the cases have been neuroinvasive, 95 percent of which required hospitalization. During the 2003 epidemic, Texas had a total of 439 neuroinvasive cases.
"This will be our worst year," Lakey said. He added that additional cases and deaths are expected to be entered into state databases as soon as today.
Dallas County alone has experienced 309 cases (152 neuroinvasive) with 12 deaths. Lakey said the county completed aerial spraying last Thursday night, and in total sprayed 437,500 acres twice for mosquitoes over six nights in addition to ground spraying.
Last Wednesday, Lakey had said there had been 586 cases of West Nile virus including 21 deaths throughout Texas and in Dallas County alone, there were 270 cases and 11 deaths.
A Smaller county in Texas, Denton, has also reported 128 cases and two deaths, and 30 cities in the county have opted in for aerial spraying starting tomorrow night.
Nationwide, over 70 percent of cases come from six states: Texas, South Dakota, Mississippi, Oklahoma, Louisiana, and Michigan.
The CDC does not anticipate Hurricane Isaac will worsen the outbreak because hurricanes and floods do not typically result in increased cases of West Nile virus, despite a greater likelihood of standing water. Dr. Peterson said these events tend to disturb the ecology of the area and interrupt the transmission cycle between birds and mosquitoes. Nevertheless, he said the CDC saw small West Nile increases after Hurricane Katrina - likely because of increased outdoor exposure - so the agency is working with local authorities just in case
About 80 percent of people infected with West Nile virus won't show any symptoms, but 20 percent may develop a fever, headache, body ache, vomiting, swollen lymph glands or a skin rash, what officials refer to as "West Nile fever" or "non-neuroinvasive" West Nile virus.
CDC data suggests one in 150 people will develop severe neuroinvasive illness, which may result in high fever, neck stiffness, convulsions, vision loss, paralysis, coma and that may be permanent - or even cause death. People over 50 and those with compromised immune systems are at the highest risk.
Reducing your risk for West Nile virus starts by reducing your risks for bug bites.
The CDC advises applying an insect repellant that contains an EPA-registered active ingredient, such as DEET, to skin or clothing before you head out doors. People should keep in mind mosquitoes are more likely to bite at dusk and dawn, and should also remove standing water puddles from their property to prevent mosquitoes from breeding.