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.
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
Allocation
RANDOMIZED
Uniforms and work clothing treated with permethrin according to proprietary process used by Insect Shield, Inc.
University of Rhode Island
Kingston, Rhode Island, United States
Number of Work Related Tick Bites Per Week
Reported tick bites, defined as ticks attached to or embedded in the skin.
Time frame: Weekly for two years
Change in permethrin metabolite levels after 3 weeks
Permethrin metabolites measured in urine, compared to baseline prior to wearing clothing.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: Enrollment to 1 year after study initiation
Change in tick repellency after 2 years
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Purpose
PREVENTION
Masking
DOUBLE
Enrollment
135
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.
Time frame: 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.
Time frame: 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.
Time frame: Study year 1 to study year 2