Tick-borne Illness and Clothing Study of Rhode Island

University of Rhode Island, East Carolina University, National Institute for Occupational Safety and Health (NIOSH/CDC)

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.

Uniforms and work clothing (including pants, shorts, shirts, socks, and hats) treated with long-lasting permethrin by Insect Shield.

Uniforms and work clothing treated with permethrin according to proprietary process used by Insect Shield, Inc.

Measurement of the chemical concentration of clothing samples after study year 1, compared against concentration of a newly treated clothing sample.

Measurement of the chemical concentration of clothing samples after study year 2, compared against concentration of a newly treated clothing sample.

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.

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.

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.

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.

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

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.