By Marice Richter DALLAS (Reuters) - The number of West Nile
virus infections in the United States has jumped more than 60
percent in the past week in what federal officials say is one of
the country's biggest-ever outbreaks of the disease. The U.S.
Centers for Disease Control said on Wednesday that 1,118 cases
and 41 deaths had been reported so far this year, up from fewer
than 700 cases and 26 deaths just one week ago. That is the
highest number of West Nile virus infections reported through
the third week of August since the virus was first detected in
the United States in 1999, the CDC said. The worst U.S. outbreak
occurred in 2003, with 9,862 cases and 264 deaths that year.
"We're in the midst of one of the largest West Nile virus
outbreaks ever seen in the United States," said Dr. Lyle
Petersen, director of the division of vector-borne infectious
diseases for the CDC. Federal officials are stumped by the
severity of the outbreak. Cases usually flare up in the summer
because the illness is most often tra