Aerial Spraying Against West Nile Needs Debate

Attention-span test: You do remember ... please tell me you remember ... that they sprayed pesticide on you from airplanes last August. I am trying to find out if they plan to spray stuff on us again next summer. Apparently that will be up to the U.S. Centers for Disease Control and Prevention.

I had a good conversation last week with one of the lead CDC scientists who were here last summer and pushed local officials to use aerial spraying. More on that in a moment. Right off, I can tell you that nobody knows whether last summer's spraying did any good.

Nobody. Not yet. I know that you have heard different. Right after the spraying, local officials were tossing around numbers like "93 percent effective." Nah. That was based on a report from the CDC that even the CDC told me last week was "extremely preliminary." It will be next month at the earliest before the CDC will have any kind of report it's willing to stand by to tell us if the spraying worked.

County officials, meanwhile, continue to sell last summer's spraying as a big success. No officials here are even talking about risks to human life from pesticide exposure.

Even though scientists at the University of Texas recommended that pregnant women leave the county last summer to avoid getting doused, County Judge Clay Jenkins and Dallas Mayor Mike Rawlings decided they had no choice but to spray the county with some stuff called endocrine disruptors to combat West Nile disease. Endocrine disruptors attack the immune systems of insects.

The UT scientists say the disruptors attack the immune systems of unborn children too. Jenkins and Rawlings felt they had to roll out the spray planes because Dallas was beset by a serious epidemic. In the end the total death toll here from West Nile was 18.

By all accounts the CDC was early and aggressive in its role here last summer promoting the adoption of aerial spraying. Two CDC scientists in particular pushed local officials to spray from planes — research entomologist Janet McAllister and Robert S. Nasci, a Ph.D. specialist in mosquito-borne disease. Jenkins told me last week he is awaiting their advice on what to do next year. McAllister told me the report will not be finished before December.

Jenkins says he will base any decision about spraying next summer on that report. "Wherever the science leads, that's where I will go," he said.

At the end of last summer's spraying, McAllister and Nasci gave the county a preliminary report indicating the airplanes were a big success, knocking down 93 percent of the bad skeeters in places they bombed. But Dallas entomologist Gene Helmick-Richardson, an airplane skeptic, told me last week he considers the CDC's preliminary report "total bullshit," tossed off way too fast to reflect any serious analysis.

McAllister did not use the same term to describe her own report, but she did say last week, "It was extremely preliminary, because that was based on information we had gathered at the time, so that did not include final testing."

The issue is whether the airplanes really reduced West Nile in Dallas or simply sprayed at a time when the disease was already collapsing on its own because of seasonal cycles. Last week I sat in on a lecture by Dr. Wendy Chung, chief epidemiologist for Dallas County, in front of several hundred public health students at Brookhaven College. She gave them chapter and verse on the process leading up to the decision to spray.

I would have to say the general tenor of her presentation was triumphal, including a reference describing the decision by Jenkins, her boss, to call in the airplanes as "courageous." But when she was done, I asked her if the bombing had done any good.

She said, "The official report from the CDC, the analysis, is ongoing, and the final determination should be forthcoming, we hope. What it appears is that the aerial spraying was done at a time when the activity of West Nile mosquitoes had already started to be somewhat on a decline. So it's difficult to prove whether the spraying measures hastened the decline of West Nile activity in the area or not."

Yeah. I will take that as, "No clue, stay tuned."

I plan to stay tuned. Chung's hour-long lecture, with discourses on media support for the airplanes, a history of West Nile in Dallas and mentions of unspecified political controversy, included no discussion or mention at all of endocrine disruptors. I don't get how anybody can even do the math on this without at least trying first to find out what the risks are.

I know. I know. You're going to say to me, "What about the risk of death and injury from West Nile?" Of course. That's the biggest part of the math. But there is math to be done.

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Jim Schutze has been the city columnist for the Dallas Observer since 1998. He has been a recipient of the Association of Alternative Newsweeklies’ national award for best commentary and Lincoln University’s national Unity Award for writing on civil rights and racial issues. In 2011 he was admitted to the Texas Institute of Letters.
Contact: Jim Schutze