Current West Nile outbreak surpasses last year's

Robert Roos  News Editor

Sep 25, 2002 (CIDRAP News) – This year's West Nile virus outbreak in the United States has far surpassed last year's in number of cases, but the death toll remains lower than last year's, according to the latest count from the Centers for Disease Control and Prevention (CDC).

The official count reached 4,827 cases yesterday, with 93 deaths, the CDC reported in the Sep 26 Morbidity and Mortality Weekly Report. In all of 2003 the nation had 4,156 cases and 284 deaths.

Thirty states reported a total of 690 new West Nile cases to the CDC from Sep 18 through 24, including 13 fatal cases, according to the report. That signaled a slower pace than the previous week, when 1,214 new cases, with 26 deaths, were reported by 28 states.

The case count seems likely to go significantly higher before this year's outbreak is over, because at least some states have backlogs of cases that have not yet been reported to the CDC. For example, the Colorado Department of Public Health and Environment Web site listed 1,886 cases and 40 deaths as of yesterday, whereas the CDC report listed the state as having 1,542 cases and 27 deaths. The states report cases to the CDC through a Web-based system called ArboNET.

Susan Montgomery, a member of the CDC's Epidemic Intelligence Service, told CIDRAP News, "There's a lot of information for these hard-hit states to handle, and there can be a lag" in their reporting. "They may have cases reported on state Web sites that are in preliminary stages of investigation. For instance, in Colorado and Nebraska they may not have had a chance to submit them through ArboNET."

But compared with many other diseases, West Nile cases are reported very quickly, said Montgomery, who works in the CDC's Division of Vector-Borne Infectious Diseases. "I have to say that states are doing an amazingly good job of getting these reports in," she added.

According to the CDC, states with the largest outbreaks were Colorado, 1,542 cases; Nebraska, 788; South Dakota, 699; Texas, 311; and Wyoming, 302. Colorado also has had the highest death toll, with 27, followed by Nebraska (13), South Dakota (8), Texas (7), Wyoming (7), and New York (5).

Nevada reported its first human West Nile case in the past week. States that had not yet reported any human cases to the CDC as of yesterday were Maine, Vermont, West Virginia, Michigan, Idaho, Washington, Oregon, Alaska, and Hawaii.