News

DEC official defends 4-poster

The state environmental official who oversaw a three-year test of 4-poster tick-killing stations on Shelter Island says two studies have shown or postulated a connection between 4-poster deployment and a possible drop in the incidence of Lyme disease among humans living nearby.

Reacting to a Shelter Island resident’s argument to the Town Board last week that there is no statistical connection between 4-poster deployment and a decline in Lyme disease, the DEC’s Vincent Palmer sent an email to people involved in the 4-poster program citing a Connecticut study conducted in 2011. It found a correlation between 4-posters and fewer people nearby developing the telltale rash associated with Lyme disease known as erythema migrans.

A pesticide specialist  who is special assistant to the DEC commissioner, Mr. Palmer also cited the U.S. Department of Agriculture’s Northeast Area Wide Tick Control project, the results of which were published in 2009. The authors of the project report found that “the implementation of this technology in high-risk endemic communities would have the potential for reducing the incidence of Lyme disease over large areas and thus impacting the current epidemic of Lyme disease.”

“I saw an article in the Shelter Island Reporter,” Mr. Palmer wrote in his recent email to 110 people involved in 4-poster studies, “in which a resident questioned what impact use of 4-poster tick management technology may have had on the human incidence of Lyme disease within the Shelter Island community. The following peer-reviewed, published scientific literature came to mind as I read the article.”

He noted that one of the two attached reports covered a Connecticut study that compared the reduction of deer populations through hunting with the human incidence of Lyme disease; and also compared the reduction of tick populations through use of the 4-poster and the human incidence of Lyme disease.

“Physician-diagnosed erythema migrans (EM) rash cases were used as a surrogate for incident Lyme disease cases” in the study, he added, which was titled, “Evaluation of deer-Targeted Interventions on Lyme Disease Incidence in Connecticut” and published in 2011 by scientists from the Yale School of Public Health’s Connecticut Emerging Infections Program.

“Our findings suggest that the 4-poster device was effective in decreasing the incidence of EM rash in an endemic area,” the authors wrote in a report summary. “Despite a decrease in EM rash incidence, however, we did not find a statistically significant effect of the deer hunt on EM rash incidence, probably due to LD (Lyme disease) reporting issues, study design limitations and the small population size.

“Further study is necessary to conclusively evaluate the effect of deer-targeted tick-control interventions on LD incidence. A prospective, multi-year study designed with consistent surveillance methods, a large population and established control areas could provide reliable data for analyzing the effectiveness of deer-targeted interventions. A combination of deer-targeted and other interventions, such as education, may ultimately prove to be successful in preventing LD in endemic areas.”

He also quoted from the final report of the USDA Northeast Area Wide Tick Control project, finding that deer ticks depend on white-tailed deer so that rendering “deer incapable of hosting adult I. scapularis (deer tick or black-legged tick) through acaricide treatment should reduce the risk of Lyme disease to the same extent as deer removal, and perhaps more efficiently since the ticks are killed rather than starved.”

“As adult I. scapularis feed upon deer only during the fall (October– December) and spring (March–April) months, and immature stages feed primarily on other hosts, a shorter treatment schedule for deer would be required than that required for A. americanum (Lone Star tick). Assuming similar efficacy with I. scapularis, the implementation of this technology in high-risk endemic communities would have the potential for reducing the incidence of Lyme disease over large areas and thus impacting the current epidemic of Lyme disease.”

A long-time critic of the 4-poster program, resident Richard Kelly appeared before the Town Board during its audience participation segment on June 26. He circulated tables he said came from New York State Health Department records that showed a very low incidence of the disease on the Island, from a high of 26 cases in the year 2000 to fewer than five cases a year in most years since 2003.

“You need more data” than that produced by dragging for ticks “to say it works,” Mr. Kelly said of the 4-poster, which applies a permethrin solution to the heads and necks of deer as they feed on corn.

A Cornell study of a three-year 4-poster trial here from 2008 through 2010, using North Haven as a control site, showed the 4-posters were highly effective at killing ticks in a wide area. But the goal of the 4-poster program has been to reduce the incidence of Lyme and other tick-borne diseases. Mr. Kelly said the state data showed no connection between the devices and any decline.