Acquired Tick Resistance in Naturally Exposed Participants

NCT07479537 | Active Not Recruiting DMC

• 1 other identifier: NL-009527
• Study Type: interventional
• Target: 24
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Tick Bites; Tick Resistance

Keywords

Tick resistance in naturally exposed individuals; tick resistance in tick-naive individuals

Outcome Measures

Primary Outcomes (1)

• Tick feeding: tick weight

  Tick weight measured in mg after complete feeding of the tick

  From the start of the tick challenge until feeding to repletion of the ticks (max 10 days)

Secondary Outcomes (5)

• Tick feeding: tick mortality

  From the start of the tick challenge until feeding to repletion of the ticks (max 10 days)

• Host reaction: redness

  Redness will be monitored at day 2 and the last day of the tick challenge

• Host reaction: itch

  Itch is measures daily during the tick challenge (From the start of the tick challenge until feeding to repletion of the ticks (max 10 days)

• Host immune response: humoral

  From the start of the challenge, day 2, day 5, final day of challenge (day 5-10) depending upon tick feeding, 3-5 weeks after the challenge and 10-12 weeks after the challenge

• Host immune response: cellular

  From the start of the challenge, day 2, day 5, final day of challenge (day 5-10) depending upon tick feeding, 3-5 weeks after the challenge and 10-12 weeks after the challenge

Study Arms (3)

Tick naive individuals

EXPERIMENTAL

Individuals who have never been bitten by ticks before (as far as known)

Other: Tick challenge

Supposed tick immune individuals

EXPERIMENTAL

Individuals who have been bitten by a lot of ticks before and experience a local reaction after each tickbite.

Other: Tick challenge

Previous TICK ME participants

EXPERIMENTAL

Individuals who have participated in the TICK ME study

Other: Tick challenge

Interventions

Tick challenge OTHER

uninfected ixodes scapularis ticks will be placed underneath a closed dressing

Previous TICK ME participants; Supposed tick immune individuals; Tick naive individuals

Eligibility Criteria

• Age: 18 Years - 70 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Naturally acquired self-reported tick resistant individuals:
• Age: 18 - 70 years;
• History of repeated tick bites
• Local reaction (like redness or itch) at place of previous tick bites and/or signs of impaired tick feeding after bite (anamnestic)
• Controls:
• Age: 18 years - 70 years;
• Experimentally acquired tick resistant individuals:
• Previous participant in the TICK ME study that has completed all 4 challenges
• Age: 18 years - 70 years;

You may not qualify if:

• Current suspicion of any tick-borne disease
• Diagnosed with tick-borne disease within the last year
• Chronic skin condition affecting the skin of the arm;
• Inability to maintain the dressing for any reason;
• Known immunodeficiency or autoimmune disease;
• Use of systemic immunomodulating drugs or chemotherapy, current or in the past;
• Chronic use of antibiotics;
• Unable to give informed consent or do not have a thorough command of the Dutch language;
• Refusal to participate in specimen collection and storage for future study related use;
• Pregnant or breastfeeding women;
• Not willing to use adequate contraception during the study period;
• Red meat allergy (both medically confirmed and self-reported);
• Use of investigational therapy and devices during the time of the study;
• Any other condition that, in the opinion of the investigator, would make the patient unsuitable for enrolment or could interfere with the patient participating in and completing the study.
• Known history of tick bites;

Sponsors & Collaborators

• Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA): lead

Study Sites (1)

Amsterdam UMC

Amsterdam, North Holland, 1105AZ, Netherlands

Location

MeSH Terms

Conditions

Tick Bites

Condition Hierarchy (Ancestors)

Bites and Stings; Poisoning; Chemically-Induced Disorders; Wounds and Injuries

Study Officials

• Joppe W Hovius, Prof. Dr.

  Amsterdam UMC

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: prof. dr.

Study Record Dates

• First Submitted: December 3, 2025
• First Posted: March 18, 2026
• Study Start: August 14, 2025
• Primary Completion: April 1, 2026
• Study Completion (Estimated): June 1, 2026
• Last Updated: March 18, 2026

Record last verified: 2026-03

Locations

NL (1)