Banshee Reeks Nature Preserve in Leesburg. After years of debate, Loudoun has decided not to spray its public parks for ticks. (Ricky Carioti/The Washington Post)

When Loudoun declared war against the rampant spread of Lyme disease in 2012, a dispute quickly arose over one of the county’s tactics of choice: using a potent pesticide spray at public parks, a strategy that was intended to kill Lyme-carrying ticks but that also raised concerns about its effectiveness and possible harm to wildlife.

Beekeepers worried that the bifenthrin-based spray would wreak havoc with their colonies and damage vulnerable populations of wild honeybees. Conservationists were concerned about chemicals leaching into waterways and killing aquatic life. Some researchers maintained there was no evidence that spraying would help reduce the number of Lyme disease infections.

Now, after years of debate and data analysis concerning the use of the spray and the presence of ticks in the county’s “high-risk” parks, the controversial strategy has been scrapped.

David Goodfriend of the Loudoun County Health Department, who provides staff support for the county’s Lyme Disease Commission, said that the commission’s recommendation was not to have the county spray the pesticide on any of the properties, based on two years of surveillance data at six highly trafficked county parks. The Loudoun Board of Supervisors agreed with the recommendation, he said.

The county conducted surveillance in 2013 and again this year, Goodfriend said, examining tick populations over a six-week period. Researchers were particularly interested in the number of nymph — meaning juvenile — black-legged ticks, the ticks that are primarily responsible for Lyme infections, Goodfriend said. (Adult black-legged ticks are more easily spotted and removed before an infection can be transmitted, health officials say.)

“One of the things that we looked for is to see if there was a time when the nymphs really start coming out in force, because if spraying is going to be done, that’s the best time to do it,” Goodfriend said. “But there were not that many black-legged ticks in the park — only about 1 percent of the ticks found were black-legged ticks — and of those, there were few nymphs.”

Loudoun, which has both rural countryside and densely populated suburban neighborhoods, has one of the highest rates of Lyme disease infection in the country and the highest in Virginia, according to health officials. More than 200 cases of Lyme disease are reported in the county each year, but officials say that the number of infections is probably much higher than that, because many cases are likely to go unreported or undiagnosed.

Mounting public concern over Lyme disease led the Board of Supervisors to declare 2012 “Lyme Disease Awareness Year” in Loudoun and establish the county Lyme Disease Commission to implement a 10-point action plan to combat the spread of the disease.

This year, the Lyme Disease Commission requested $41,500 in county funding, including $27,000 for research surrounding tick populations in the five county parks and $3,000 to spray insecticide in them. The funds set aside for the spraying of Talstar, the chosen pesticide, will go unspent this year.

That decision came as welcome news to officials with the Loudoun Wildlife Conservancy, an environmental group that has been outspoken in its concern and its skepticism over the use of the pesticide spray. The group issued a position paper in February titled “Rebalancing Loudoun’s Approach to Lyme Disease Mitigation,” citing research that questioned the corollary between spraying for ticks and reducing Lyme disease infection.

“We called on the county to emphasize data collection, education and communication in their action plan,” said Alysoun Mahoney, conservation advocacy chair for the conservancy. “We are very pleased that in its July 8 meeting, the statement by [the supervisors’ government services and operations committee] is to a great degree consistent with our recommendations. We think they’re going in the right direction.”

County officials and environmental activists have emphasized the importance of personal prevention measures to resist Lyme infection, such as wearing long, light-colored clothing, applying tick repellant and checking for ticks after being outdoors.

“I don’t want to downplay the concerns about the disease, and to the extent that the county focuses its resources about education about personal protective measures, the public will be more aware of when and how to take those kinds of steps,” Mahoney said.

Goodfriend said the county Health Department encourages residents to consider a variety of methods to prevent infection, including options related to private property. “Ticks don’t like well-mowed lawns,” he said. “There are additional ways to keep ticks away — by getting rid of rodent populations and making our properties less conducive to ticks.”

The commission will continue to concentrate its efforts on community education and outreach, Goodfriend said, and will also spend time over the summer reviewing the tick surveillance data in greater detail “to see what makes the most sense for the parks in the future.”

The commission will go back to the Board of Supervisors in the fall, he said: “Our plan is to give a more detailed evaluation of what the surveillance showed and to present the board with recommendations and options for potential intervention in county parks going forward.”

Information about Lyme disease and the county’s approach to reducing infection is at