This year's outbreak of West Nile 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.
MORE: 2 more cases of West Nile in Duval County bring total to 22
The
mosquito-borne virus causes no symptoms in about 80% of those it
infects. 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 cases, death.
MORE: Panhandle county officials report West Nile death
Nationally,
cases are up 35% from last week. Texas remained the hot spot,
accounting for 50 of the nation's 118 deaths, Petersen said in a
telephone briefing. There have been 2,636 cases of of the mosquito-borne
disease this year, 1,150 of them -- or 44% -- in Texas.
It's
believed that a mild winter and wet spring might have contributed to
the high Texas case count, but health officials there still aren't sure,
Petersen said.
The next-hardest-hit state, Louisiana, has had 10 deaths and 147 cases.
Two-thirds
of the cases have been in six states: South Dakota, Mississippi,
Michigan and Oklahoma, in addition to Texas and Louisiana.
The
West Nile virus lives in birds. Mosquitoes bite infected birds, become
infected themselves, then pass the virus to humans by biting them.
The
two worst West Nile virus years previously were 2002, when 284 people
died, and 2003, when 264 died, Petersen said. This year is on track to
top those numbers. The 2002 outbreak was centered in the East, from
Louisiana up through Chicago. The 2003 outbreak was farther west, in the
western Plains and mountain states, he said.
USA Today