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How Many West Nile Cases Warrant Mosquito Spraying in Austin?

Updated: Friday, September 7 2012, 12:40 PM CDT
In Austin/Travis County, there have now been 13 confirmed or suspected human cases of West Nile Virus infection, including one fatality.  Additionally, 69 mosquito samplings from 20 different local zip codes have tested positive for West Nile carriers, compared to zero positive tests in the last few years. 

Still, the local health authority will not spray airborne insecticide to kill the blood-suckers, except “In the event of a public health emergency” says Dr. Phil Huang, Director of the Austin/Travis County Health and Human Services Department.

We have heard that ‘public health emergency’ threshold referred to time and again, and like many Austinites, we too have wondered, “where we cross that line”, as Ashley Perez puts it.  Perez is a dog trainer who is routinely bugged by the mosquitoes, and she says the increasing incidence of West Nile this year “does elevate my concern.”

But Perez is also bothered by the thought of widespread spraying of poisons to kill them off, “I definitely feel torn”.

And that is the same dilemma facing Dr. Huang, who has the power to make the call to turn on the sprayers.  So we asked him what has to happen for this to become a public health emergency that would warrant spraying?  The answer, just like the insecticide itself, is foggy; a complicated formula involving the number of cases, how severe they are, and whether they are clustered in a particular area.

Right now, Dr. Huang says the limited benefit of spraying just doesn’t outweigh the environmental impact.  But he adds, health officials are doing something even better.  Instead of a temporarily helpful air war, crews are deploying their weapons in the water by treating stagnant pools of water around the city to “Get the mosquitoes where they are breeding…get the larvae in those areas,” explains Dr. Huang.  He says the larvacides being put into the water lasts 45 days.  He argues that’s a much more effective and measured response than spraying.  The airborne insecticide must touch mosquitoes to kill them; and Dr. Huang says the insects can build resistance if the spray is used too frequently.
Dr. Huang says the health department will send a team out and take action on a per-case basis if citizens call to report a particular mosquito hot spot.

You can either call 3-1-1 or the mosquito hotline at 512-978-0370.  You can also send an email.  The address is listed on the city’s vector control page:
http://www.austintexas.gov/department/vector-control
How Many West Nile Cases Warrant Mosquito Spraying in Austin?