Effectiveness of Residential Acaricides to Prevent Lyme and Other Tick-borne Diseases in Humans

J Infect Dis. 2016 Jul 15;214(2):182-8. doi: 10.1093/infdis/jiv775. Epub 2016 Jan 5.


Background: In the northeastern United States, tick-borne diseases are a major public health concern. In controlled studies, a single springtime application of acaricide has been shown to kill 68%-100% of ticks. Although public health authorities recommend use of acaricides to control tick populations in yards, the effectiveness of these pesticides to prevent tick bites or human tick-borne diseases is unknown.

Methods: We conducted a 2-year, randomized, double-blinded, placebo-controlled trial among 2727 households in 3 northeastern states. Households received a single springtime barrier application of bifenthrin or water according to recommended practices. Tick drags were conducted 3-4 weeks after treatment on 10% of properties. Information on human-tick encounters and tick-borne diseases was collected through monthly surveys; reports of illness were validated by medical record review.

Results: Although the abundance of questing ticks was significantly lower (63%) on acaricide-treated properties, there was no difference between treatment groups in human-tick encounters, self-reported tick-borne diseases, or medical-record-validated tick-borne diseases.

Conclusions: Used as recommended, acaricide barrier sprays do not significantly reduce the household risk of tick exposure or incidence of tick-borne disease. Measures for preventing tick-borne diseases should be evaluated against human outcomes to confirm effectiveness.

Keywords: Lyme disease; acaricide; humans; pesticide; prevention; tick-borne diseases; ticks.

Publication types

  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acaricides / administration & dosage*
  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Animals
  • Child
  • Child, Preschool
  • Double-Blind Method
  • Family Characteristics
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Middle Aged
  • New England
  • Placebos / administration & dosage
  • Pyrethrins / administration & dosage
  • Tick Bites / epidemiology
  • Tick Bites / prevention & control*
  • Tick-Borne Diseases / epidemiology
  • Tick-Borne Diseases / prevention & control*
  • Ticks / drug effects*
  • Ticks / growth & development*
  • Young Adult


  • Acaricides
  • Placebos
  • Pyrethrins
  • bifenthrin