Tick-borne Illness and Clothing Study of Rhode Island

Lyme and other tick-borne diseases pose a significant health threat to outdoor workers. This study is a double-blind randomized controlled trial of outdoor workers in Rhode Island and the surrounding area that will address the following study aims: 1) Evaluate the effectiveness of LLPI clothing in preventing tick bites among outdoor workers in Lyme endemic areas; 2) Measure the urine levels of permethrin metabolites in study subjects; and 3) Measure the loss over time of knockdown activity against ticks and of permethrin in LLPI clothing.

Study Overview

• Status: Completed
• Conditions: Tick Bites; Tick-borne Diseases
• Intervention / Treatment: Other: Permethrin Impregnated Clothing

Detailed Description

Lyme and other tick-borne diseases pose a significant health threat to outdoor workers. In a double-blind randomized controlled trial (RCT) in North Carolina outdoor workers, the investigators previously showed that long-lasting permethrin-impregnated (LLPI) clothing provided >80% protection for one year against Lone Star tick bites among outdoor workers in North Carolina. But there are three issues that need to be addressed before this finding can be translated into policy: 1) Do LLPI clothing protect against black legged ticks, the vector for Lyme disease, babesiosis and anaplasmosis? 2) What levels of permethrin and its metabolites are absorbed, and are they potentially toxic? 3) Why did the LLPI clothing in our previous study lose efficacy after a year?

Participants: The investigators will recruit 250 outdoor workers. The investigators anticipate recruiting 80, 80, 40,30, and 20 participants from NationalGrid, the RI Department of Environmental Management, the Massachusetts Department of Conservation & Recreation, the National Park Service, and the US Fish & Wildlife Service.

Procedures (methods): This will be a randomized controlled trial. All study subjects will fill out weekly tick logs, collect attached ticks for later speciation and pathogen detection, and submit annual serum samples to test for exposure to tick-borne pathogens. A randomly selected subset of 60 subjects also will be asked to submit urine samples for permethrin metabolite analysis at several time points during follow-up. An additional randomly selected subset (n=30) will be asked to submit worn items of clothing for tick knockdown testing and permethrin content analysis at the end of the first and second years of field testing.

The results of this study could help protect hundreds of thousands of outdoor workers with exposure to ticks and tick-borne pathogens.

• Study Type: Interventional
• Enrollment (Actual): 135
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Rhode Island
    • Kingston, Rhode Island, United States, 02881
      • University of Rhode Island

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• over 18 years of age,
• spending an average of 10 or more hours of outdoor work per week during peak tick season, and
• completion of written informed consent.

Exclusion Criteria:

• pregnancy or a planned pregnancy during the follow-up period (since exposure to an insecticide is involved),
• non-English speakers, or
• having a known allergy or sensitivity to insecticides

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Permethrin Impregnated Clothing; Uniforms and work clothing (including pants, shorts, shirts, socks, and hats) treated with long-lasting permethrin by Insect Shield.	Other: Permethrin Impregnated Clothing; Uniforms and work clothing treated with permethrin according to proprietary process used by Insect Shield, Inc.; Other Names: Insect Shield
No Intervention: Untreated Clothing; Uniforms and work clothing sent to Insect Shield, washed and refolded (no permethrin applied).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Work Related Tick Bites Per Week	Reported tick bites, defined as ticks attached to or embedded in the skin.	Weekly for two years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in permethrin metabolite levels after 3 weeks	Permethrin metabolites measured in urine, compared to baseline prior to wearing clothing.	Enrollment to 3 weeks after study initiation
Change in permethrin metabolite levels after 1 year	Metabolites measured in urine, compared to baseline prior to wearing clothing.	Enrollment to end of study year 1
Change in concentration of permethrin in clothing after 1 year	Measurement of the chemical concentration of clothing samples after study year 1, compared against concentration of a newly treated clothing sample.	Enrollment to end of study year 1
Change in concentration of permethrin in clothing after 2 years	Measurement of the chemical concentration of clothing samples after study year 2, compared against concentration of a newly treated clothing sample.	Enrollment to 2 years after study initiation
Change in tick repellency after 1 year	Measurement of the tick repellency ("knockdown activity") of clothing samples after study year 1, compared against concentration of a newly treated piece of clothing sample.	Enrollment to 1 year after study initiation
Change in tick repellency after 2 years	Measurement of the tick repellency ("knockdown activity") of clothing samples after study year 2, compared against concentration of a newly treated piece of clothing sample.	Enrollment to 2 years after study initiation
Pathogen seroconversion in study year 1	Seroconversion in year 1 is defined as a fourfold rise in antibody titers against pathogens of tick-borne disease when comparing titers between baseline and after year 1.	Enrollment to year 1
Pathogen seroconversion in study year 2	Seroconversion in year 2 is defined as a fourfold rise in antibody titers against pathogens of tick-borne disease when comparing titers between baseline and after year 2.	Study year 1 to study year 2

Collaborators and Investigators

• Sponsor: University of North Carolina, Chapel Hill
• Collaborators: National Institute for Occupational Safety and Health (NIOSH/CDC); East Carolina University; University of Rhode Island
• Investigators: Principal Investigator: Steven R Meshnick, MD, PhD, University of North Carolina, Chapel Hill

Publications and helpful links

Helpful Links

• A prior study, Tick-borne Illness and Clothing Study (TICS), was conducted in North Carolina by UNC. The current study uses similar methodology as described in the NC study, as it applies to outdoor workers and ticks in the Rhode Island area.

Study record dates

Study Major Dates

• Study Start (Actual): February 1, 2016
• Primary Completion (Actual): March 1, 2019
• Study Completion (Actual): December 1, 2020

Study Registration Dates

• First Submitted: November 20, 2015
• First Submitted That Met QC Criteria: November 23, 2015
• First Posted (Estimate): November 24, 2015

Study Record Updates

• Last Update Posted (Actual): March 10, 2021
• Last Update Submitted That Met QC Criteria: March 8, 2021
• Last Verified: February 1, 2021

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Chemically-Induced Disorders; Infections; Wounds and Injuries; Vector Borne Diseases; Poisoning; Bites and Stings; Tick-Borne Diseases; Tick Bites; Molecular Mechanisms of Pharmacological Action; Enzyme Inhibitors; Permethrin
• Other Study ID Numbers: 15-1770; R01OH010791 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO