Acquired Tick Resistance in Naturally Exposed Participants

Tick-borne diseases are increasing worldwide, and there are currently few effective ways to prevent them. One promising new strategy is to develop a vaccine that targets the tick itself ("anti-tick vaccine") to block the transmission of multiple pathogens. Some animals naturally develop resistance to ticks after repeated tick bites. There are indications that a similar form of acquired tick resistance (ATR) may also occur in humans who have been heavily exposed to ticks. This study investigates whether humans can naturally develop tick resistance and how this affects tick feeding. The investigators will compare people with a long history of tick bites and self-reported signs of tick resistance to people who are tick-naïve. The investigators will also include a small group of volunteers who previously participated in an experimental human tick challenge to evaluate what their reaction on tickbites is 1-2 years after their initial exposures.

NCT Number	NCT07479537
Lead Sponsor	Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA)
Conditions	Tick Bites, Tick Resistance
Enrollment	24 participants
Start Date	2025-08-14
Primary Completion	2026-04-01 (estimated)
Study Completion	2026-06-01 (estimated)
Updated on ClinicalTrials.gov	2026-06-10