This year's outbreak of West Nile virus is the most serious since the virus was discovered in the United States in 1999, but health officials hope the worst is over.
"We've turned the corner on the epidemic. West Nile virus outbreaks in the United States tend to peak in late August," said Lyle Petersen, director of the Centers for Disease Control and Prevention's Division of Vector-Borne Infectious Diseases.
The mosquito-borne virus can go unnoticed by most of those infected. The rest develop West Nile fever, with symptoms that can include fever, headache, body aches and sometimes a skin rash. About one in 150 infected people develop the rare but dangerous West Nile neuroinvasive disease, which can cause convulsions, muscle weakness, paralysis and, in some, death.
Nationally, cases are up 35% from last week. Texas remained the hot spot with 50 of the nation's 118 deaths, Petersen said in a phone briefing. There have been 2,636 cases this year, 1,150 of them in Texas. It's believed that a mild winter and wet spring, great for mosquito breeding, might have contributed to the high Texas case count, but health officials there aren't sure, Petersen says.
The next hardest-hit state, Louisiana, has had 10 deaths and 147 cases.
Two-thirds of the cases have been in six states: Texas, Louisiana, South Dakota, Mississippi, Michigan and Oklahoma.
The West Nile virus lives in birds. Mosquitoes bite infected birds, become infected themselves, then pass the virus to humans when they bite.
Most people who become infected have no symptoms. About 20% have fever, headache and body aches, nausea, vomiting and sometimes swollen lymph glands or a rash on the chest, stomach and back. These symptoms can last a few days to several weeks.
To see more of USAToday.com, or to subscribe, go to http://www.usatoday.com
Copyright 2012 USA TODAY, a division of Gannett Co. Inc.