West Nile virus makes new inroads in the West

The West Nile virus is continuing its westward journey, with states that have experienced minimal or no activity until now reporting higher numbers than last year.

Meanwhile, case numbers appear to be settling in states that have already had significant outbreaks.

For example, Arizona, which reported a total of 13 cases last year and only three -- all of which were linked to travel to other states -- in 2002, already has at least 57 cases including one death, according to a paper published in the July 9 issue of the Morbidity and Mortality Weekly Report.

Louisiana, however, which saw a large outbreak in 2002 including 329 confirmed cases, had only 124 last year and none yet reported this year.

"Most of us who've been watching this, if we had to make a prediction last year, we would have said Arizona and the Western part of the country would probably be the next hot area," said Dawn Wesson, PhD, associate professor of tropical medicine at Tulane University in New Orleans. "We haven't seen two years in a row anywhere, where there were a lot of cases."

Experts theorize that the environment is adapting to the virus and vice-versa since it emerged in New York in 1999. But, they also warn that no area is immune from it.

"Physicians need to continue to advise their patients to do whatever they can to avoid being bitten during [this time] of year," said Dr. Wesson. "The virus is still out there circulating. It may not be quite the same intensity but the difference between being infected and not infected can mean a change in the rest of your life."

Centers for Disease Control and Prevention officials warn that these numbers early in the season cannot be taken as an indication of what this year's West Nile activity may be like because of differences in reporting times.

"The reporting is not in real time," said Christine Pearson, CDC spokeswoman. "It's very difficult to make any predictions because of the number of factors that West Nile is based on, but we expect a fair amount of activity with westward expansion."