Once this year's deadly West Nile virus outbreak runs its course, public health researchers will look back to try to determine what could have been done better and look forward to try to control future outbreaks.
For now, city and county crews are still testing mosquito pools and continuing basic abatement procedures. But no more aggressive spraying treatments are planned.The virus is still in the environment, but the number of human infections is slowing, said David Jefferson, environmental health manager for Tarrant County. New cases continue to be reported because once a diagnosis is made, weeks can pass before it's confirmed and reported to the public."The last new cases that we've had [in Tarrant County] have been in the hospital since the first week in September," Jefferson said.West Nile starts diminishing about the middle of August every year."The virus seems to go down independent of the number of mosquitoes" sometime around mid-August, Jefferson said. "There are two questions: What happens to mosquitoes and what happens to the virus?"The 2012 West Nile outbreak has been the most active and lethal in state history, Texas health officials have said. The virus was first detected in the United States in 1999.As of Friday, Tarrant County had reported 261 human cases and seven deaths. Dallas County has been hit the hardest, with 368 human cases and 15 deaths. Denton County has recorded 168 human cases and two deaths.The Tarrant County Public Health website, updated Friday, reported 85 positive mosquito pools -- 12 each in Arlington and Fort Worth and smaller numbers in 15 other cities.Tarrant County health officials will issue an "after-action" report once the outbreak ends, which should be in October or early November, Jefferson said. Regional and state reports, as well as a report from the U.S. Centers for Disease Control and Prevention, are expected before the end of the year.Denton County health officials are seeing similar reductions in cases and positive mosquito pools, said Bob Martinez, emergency preparedness coordinator for the Denton County Health Department.After aerial spraying, Denton County reported a 56 percent reduction in all mosquitoes and a 60 percent reduction in mosquitoes that carry the virus."The number of new cases of WNV has decreased substantially since aerial spraying; however, it is premature to conclude that these results are solely attributable to aerial spraying," the report stated.Tarrant continues ground spraying in hard-to-access pockets of the county, Jefferson said. In Fort Worth, mosquito testing continues, but no more spraying is planned, according to a city official."The real need is for us to understand this disease," Jefferson said. "We hope this terrible year will give us enough information for us to make better decisions in the future."This report includes material from the Star-Telegram archives.Mitch Mitchell, 817-390-7752Twitter: @mitchmitchel3Have more to add? News tip? Tell us
