Fifth West Nile victim dies

Outbreak now worst in U.S. history

Experts emphasize that the rates of infection remain quite low because only 1 percent of mosquitoes carry the virus.

BATON ROUGE, Louisiana (CNN) -- A fifth person has died from West Nile virus in Louisiana and 71 cases have been confirmed, making this the nation's worst outbreak of the disease, authorities reported Tuesday.

The fifth Louisiana victim died last week, but the cause of death was not confirmed until Tuesday, said Dr. Erin Brewer, regional medical director for the state's Office of Public Health.

There are 71 confirmed cases statewide, Bob Johannessen, a spokesman for the Louisiana Department of Health and Hospitals, said Tuesday.

"There's no way to predict what's going to happen, but we thought we'd get more [cases], because they started in late June," Brewer said. "We knew we were early in the season, and knew the potential for more human cases was always there."

Illinois also reported Tuesday its first human case of West Nile virus, saying a 22-year-old woman was infected. The woman reported only minor symptoms -- fever, achy muscles and a slight rash -- and has since recovered.

CNN NewsPass VIDEO So far, 71 cases of the deadly West Nile virus have been confirmed in Louisiana, making this the nation's worst outbreak of the disease. CNN's Rea Blakey reports (August 7) Play video CNN's Ed Lavandera reports on efforts to control West Nile virus after recent deaths in Louisiana. (August 4) Play video   EXTRA INFORMATION West Nile virus: Outbreaks in the U.S. from 2000 to 2002  Interactive: Understanding West Nile virus    RESOURCES Map: Where infected birds have been found in 2002    MORE STORIES A West Nile survivor's story  Infectious diseases: A problem the world over

Meanwhile, health officials are concerned the virus may be moving at a faster rate and infecting younger people than expected.

Alarmed by how many cases have already been confirmed, David Hood, secretary for Louisiana's Health and Hospitals Department, noted, "We have about three months left of warm weather here in Louisiana."

The West Nile virus was discovered in Uganda in 1937, then found its way to New York in 1999, Hood said. That New York outbreak was the largest outbreak in the nation's history, resulting in 62 cases, including seven deaths.

The virus has since spread by migrating birds, scientist believe. It was found near New Orleans in 2001.

"We were expecting we would see an outbreak in 2002, but maybe not of the magnitude we're seeing now," Hood said.

So far this year, there have been "more cases than have occurred in the three previous years," said Jim Hughes, director of the National Center for Infectious Diseases. "We are concerned about what the remainder of the year holds in store for us." Most of the cases have been in Louisiana, Texas and Mississippi.

The Mississippi-Louisiana-Texas area, he added, "is a part of the country that is particularly susceptible to mosquito-borne virus transmission," Hughes told CNN.

The West Nile virus is now in nearly every state east of the Mississippi, he said, and experts predict it's only a matter of time before California will report its first cases of the potentially fatal virus.

People over 50 and those with compromised immune systems are usually hardest hit by the virus, which can bring high fever, encephalitis and death. But the latest cases are not reflecting that pattern, and "most of the West Nile experts think [all ages] are probably equally at risk for getting infected," said Dr. Erin Brewer, a Louisiana regional medical director.

Dr. Julie Gerberding, director of the Centers for Disease Control and Prevention, said the cases in Louisiana, Mississippi and Texas have raised concerns because they have occurred earlier in the year than expected and are showing up in younger people.

"But, it's too soon to say for sure if there is any change in the pattern," Gerberding said.

"It definitely makes us concerned about what is yet to come, and that's why we're trying to get the message out [for people] to practice sensible precautions when they go outdoors and make sure their homes are protected [from mosquitoes]," Brewer said.

Experts emphasized that the rates of infection remain quite low because only 1 percent of mosquitoes carry the disease, and in the event a person is bitten by a carrier insect, the chance of developing serious symptoms is less than 1 percent.