* 280 cases reported in past week
* 2003 was worst year on record in U.S.
By Marice Richter
DALLAS, Oct 10 (Reuters) – The outbreak of West Nile disease
in the United States moved a step closer on Wednesday to
becoming the second worst on record with federal health
authorities reporting 280 cases of the virus-caused illness over
the past week.
There have now been 4,249 cases of West Nile recorded this
year, according to the Centers for Disease Control and
Prevention, 20 cases fewer than in 2006, the second-largest
outbreak on record.
The number of deaths rose by five to 168 since last week,
the CDC said.
The worst year on record for West Nile disease was 2003,
when 9,862 cases were reported, the CDC said.
The pace of new cases of the disease – which is transmitted
from infected birds to humans by mosquitoes — has slowed since
late summer, authorities said.
More than 70 percent of the cases have been reported in
eight states: Texas, Mississippi, Michigan, South Dakota,
Louisiana, Oklahoma, Illinois and California. Texas has been the
hardest hit, recording close to 40 percent of the cases in the
country, according to the CDC.
The Dallas-Fort Worth area has been the epicenter of this
year’s outbreak, with 33 deaths, according to the Texas
Department of State Health Services.
The Dallas Morning News reported Wednesday that health
officials in Tarrant County, home to Fort Worth, may have vastly
underreported cases of the serious neuroinvasive form of West
Nile.
The report said the number of cases detected through Tarrant
County blood bank screenings – information that helps public
officials determine the size of an outbreak – differs
significantly from what officials there have reported.
But state health officials said it was unlikely cases were
overlooked.
The severe neuroinvasive form of the disease almost always
requires hospitalization and can lead to meningitis,
encephalitis and death, according to the CDC.
“Neuroinvasive disease is not subtle,” said Carrie Williams,
a spokeswoman for the Texas health department. “We’re confident
physicians knew about the outbreak and were on the lookout for
disease.”
Nationwide, half of cases reported to the CDC have been of
the neuroinvasive form. The other half are West Nile Fever, a
milder form which causes flu-like symptoms and is not deadly.
Outbreaks tend to be unpredictable and are typically
triggered by a combination of hot weather and intermittent
rainfall as well as ecological factors such as the size of the
bird and mosquito populations.
(Editing by Corrie MacLaggan, James B. Kelleher and Jim Loney)
