Local and state health officials call the historic West Nile outbreak an epidemic. "It's a public health emergency here in Dallas County," warned Dr. David Lakey, commissioner of the Texas Department of State Health Services.

Dallas County is initiating its most aggressive spraying plan yet—both from the ground and, most likely, from the air. But what are the health effects of aerial spraying? There are strong opinions on both sides of the issue.

Officials say they will launch a public education campaign to educate the public before starting aerial spraying.

There is no vaccine for the virus, which has been in the U.S. since about 1999, according to the U.S. Centers for Disease Control. The virus, which most often affects people over age 50, can cause high fevers, headaches and disorientation. The large number of West Nile cases this year is due to the extremely hot weather and recent rains, according to the agency.

Public health officials typically advise residents of mosquito-prone areas to drain standing water, apply insect repellent containing the ingredient DEET and wear long-sleeve shirts and long pants. But local and state health officials say it's clear that those warnings and ongoing ground-based spraying aren't enough.

"It seems like the avoidance strategy is not working, so now you have to kill the bug," said Dr. Rick Snyder, president of the Dallas County Medical Society.

Aerial spraying is controversial. Some fear health effects from chemicals falling on them from the sky, and others have questioned whether the approach was scientifically proven to stop West Nile cases.

Dallas Mayor Mike Rawlings asked Dallas residents for their opinion on aerial spraying on his Facebook page. Nearly all the responses were against the idea, such as this one from Amy Wallace Cowan:

“Only 1 in 5 people who contract West Nile will ever show a symptom. Only 1 in 150 will have serious symptoms, per the CDC. There are many citizens who practice organic gardening and lifestyles that should be taken into consideration. This is going to wreck havoc on our ecosystem.”

“It's not just mosquitoes that will die—it will wipe out honey bees, butterflies, and other beneficial pollinators. The cost weighed against the benefit just doesn't make sense. There are other, more targeted means of dealing with this. Send code enforcement to every single address with a pool. Get every business with a fountain, including the city, to make sure their water isn't stagnant water. Make bug sprays such as “Off” free to each household with water bill. The city and county have a lot of other options before they essentially crop dust us with poison.”

You can read other reactions to aerial spraying on the Mayor’s Facebook page here:

https://apps.facebook.com/forumforpages/135030976598069/219a064e-a5b3-4762-9fe9-8d0599647907/0

But at least one study in California has concluded that the odds of West Nile infection are about six times lower in treated areas than those that are untreated.

The American Mosquito Control Association doesn't keep exact statistics, but an association spokesman said aerial spraying is common in Florida, and ongoing programs exist in other states including Louisiana, New Jersey, Georgia, North Carolina, Michigan and Minnesota.

The Association cites these points in support of aerial spraying when West Nile has reached the level it has in Dallas County:

• The aerial spraying would have to be 1,000 times greater than permitted by the U.S. Environmental Protection Agency to be considered a risk to humans or pets.
• Aerial spraying is designed to kill mosquitoes in flight; mosquitoes in ditches, drains and other “nesting” areas are reached through ground spraying efforts.
• Bees, dragon flies and other “beneficial” insects are not active at night and should not be adversely affected by aerial spraying.
• Residents should stay inside during spraying.

For more on the West Nile virus, visit the CDC’s West Nile information web site: http://www.cdc.gov/ncidod/dvbid/westnile/