Tick BitesTICK REACTNCT07479537
Acquired Tick Resistance in Naturally Exposed Participants
A study testing Tick challenge in people with Tick Bites and Tick Resistance, run by Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA) at 1 site in Netherlands.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 70 yearsHealthy volunteers can take part
- Conditions the study is for
- Tick Bites, Tick Resistance
- What is being tested?
- Tick challenge
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 24 participants
- Where
- 1 siteNetherlands
- Study dates
- 14 Aug 2025to 1 Jun 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 70 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- 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;
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- Experimentally acquired tick resistant individuals:
- Previous participant in the TICK ME study that has completed all 4 challenges
- Age: 18 years - 70 years;
Who cannot join
- 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;
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- 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.
- Additional exclusion criteria for controls:
- Known history of tick bites;
- Positive Borrelia serology (VlsE1/PepC10 ELISA);
- Known history or current suspicion on any tick-borne disease
- Additional exclusion criteria for experimentally acquired tick resistant individuals:
- History of tick bites acquired outside of TICK ME study;
- Positive Borrelia serology (VlsE1/PepC10 ELISA);
- Known history or current suspicion on any tick-borne disease
Trial locations and contacts
1 site in 1 country.
About this study
Official title: The Uninfected Ixodes Scapularis Human Tick Challenge Model - 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.
Read the detailed description
Study Objectives Primary Objective To determine whether humans develop naturally acquired tick resistance by measuring tick feeding success, specifically the weight of ticks after feeding.
Secondary Objectives To measure additional tick feeding parameters (tick mortality, attachment rate, duration of feeding, and molting).
To assess clinical skin reactions such as itch and redness. To study immune responses (antibodies and immune cells) against tick saliva proteins in all groups.
To identify tick salivary antigens that may be useful for future anti-tick vaccine development.
Study Design Single-center, open-label human experimental tick challenge study.
Three groups:
ATR group: 11 adults with extensive prior tick exposure and self-reported signs of tick resistance.
Control group: 11 adults with no significant tick exposure. Follow-up challenge group: Up to 4 adults previously challenged in the "TICK ME" study.
Outcome measures Primary Outcome Measure Post-feeding tick weight
Secondary Outcome Measures Tick mortality, attachment rate, days attached, and molting success Clinical skin responses (itch, redness) Immune responses to tick salivary proteins Skin biopsy analyses
- Conditions
- Tick Bites, Tick Resistance
- Being tested
- Tick challenge
- Keywords
- Tick resistance in naturally exposed individuals, tick resistance in tick-naive individuals
- Medical subject headings
- Tick Bites
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Tick challengeOther
uninfected ixodes scapularis ticks will be placed underneath a closed dressing
| Study group | Role | What they receive |
|---|---|---|
| Tick naive individuals | Experimental | Individuals who have never been bitten by ticks before (as far as known) Receives: 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. Receives: Other: Tick challenge |
| Previous TICK ME participants | Experimental | Individuals who have participated in the TICK ME study Receives: Other: Tick challenge |
What is being measured
The primary outcome is the main question the study is designed to answer.
Tick feeding: tick weight
Tick weight measured in mg after complete feeding of the tick
Measured: From the start of the tick challenge until feeding to repletion of the ticks (max 10 days)
Secondary outcomes (5)
Tick feeding: tick mortality
Tick mortality in % of fed ticks
Measured: From the start of the tick challenge until feeding to repletion of the ticks (max 10 days)
Host reaction: redness
Redness (using a standardized clinical erythema (CEA) score (scale 0-4) which is scored by physicians using photographs of tick bite lesions)
Measured: Redness will be monitored at day 2 and the last day of the tick challenge
Host reaction: itch
Itch (using Visual Analogue Scale 0-100) as a sign of a clinical reaction of the host
Measured: 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
Humoral (qualitative by characterizing antibodies recognizing anti-tick antigens using a yeast surface display expressing tick salivary gland proteins)
Measured: 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
Cellular (immunophenotyping of the different immune subsets in collected PBMCs at the specified time points) of immune responses in blood
Measured: 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
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Mar 2026
- Study start14 Aug 2025
- Primary completion1 Apr 2026
- Study completion1 Jun 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Tick BitesStudies of the same condition, open and under way.
- More trials run by Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA)The sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 24 participants (actual)
Sponsor and investigators
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, prof. J.W.R. Hovius, MD, PhD, Amsterdam UMC, location AMC
- Investigators
- Joppe W Hovius, Prof. Dr., Principal investigator, Amsterdam UMC
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07479537
- Sponsor's protocol ID
- NL-009527
- Acronym
- TICK REACT
- Status last verified
- Jun 2026
- First submitted
- 3 Dec 2025
- Last updated
- 10 Jun 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: The descision about sharing the IPD will follow
Study at a glance
From the registry record, last updated by the sponsor on 10 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Uninfected Ixodes Scapularis Human Tick Challenge Model - Acquired Tick Resistance in Naturally Exposed Participants
- ClinicalTrials.gov ID
- NCT07479537
- Acronym / sponsor ID
- TICK REACT / NL-009527
- Conditions
- Tick Bites, Tick Resistance
- Keywords
- Tick resistance in naturally exposed individuals, tick resistance in tick-naive individuals
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 24 participants (actual)
- Lead sponsor
- Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA)University, hospital or other
- Study start
- 14 Aug 2025 (actual)
- Primary completion
- 1 Apr 2026 (actual)
- Study completion
- 1 Jun 2026 (actual)
- First posted
- 18 Mar 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
Study Objectives Primary Objective To determine whether humans develop naturally acquired tick resistance by measuring tick feeding success, specifically the weight of ticks after feeding.
Secondary Objectives To measure additional tick feeding parameters (tick mortality, attachment rate, duration of feeding, and molting).
To assess clinical skin reactions such as itch and redness. To study immune responses (antibodies and immune cells) against tick saliva proteins in all groups.
To identify tick salivary antigens that may be useful for future anti-tick vaccine development.
Study Design Single-center, open-label human experimental tick challenge study.
Three groups:
ATR group: 11 adults with extensive prior tick exposure and self-reported signs of tick resistance.
Control group: 11 adults with no significant tick exposure. Follow-up challenge group: Up to 4 adults previously challenged in the "TICK ME" study.
Outcome measures Primary Outcome Measure Post-feeding tick weight
Secondary Outcome Measures Tick mortality, attachment rate, days attached, and molting success Clinical skin responses (itch, redness) Immune responses to tick salivary proteins Skin biopsy analyses
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Tick naive individuals | Experimental | Other: Tick challengeIndividuals who have never been bitten by ticks before (as far as known) |
| Supposed tick immune individuals | Experimental | Other: Tick challengeIndividuals who have been bitten by a lot of ticks before and experience a local reaction after each tickbite. |
| Previous TICK ME participants | Experimental | Other: Tick challengeIndividuals who have participated in the TICK ME study |
Who may qualify
- Ages
- 18 to 70 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (9 listed)
- 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)
- Age: 18 years - 70 years;
- Previous participant in the TICK ME study that has completed all 4 challenges
Key exclusion criteria (22 listed)
- 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;
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Tick challengeuninfected ixodes scapularis ticks will be placed underneath a closed dressing | Other | Previous TICK ME participants, Supposed tick immune individuals, Tick naive individuals |
Primary outcome
Tick feeding: tick weight
Time frame: From the start of the tick challenge until feeding to repletion of the ticks (max 10 days)
Tick weight measured in mg after complete feeding of the tick
5 secondary outcomes
Tick feeding: tick mortality
Time frame: From the start of the tick challenge until feeding to repletion of the ticks (max 10 days)
Host reaction: redness
Time frame: Redness will be monitored at day 2 and the last day of the tick challenge
Host reaction: itch
Time frame: 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
Time frame: 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
Time frame: 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
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 Jun 2026.
- Individual participant dataSharing planned: Undecided. The descision about sharing the IPD will follow
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Joppe W Hovius, Prof. Dr. principal investigator
Amsterdam UMC
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Tick challenge in people with Tick Bites and Tick Resistance, run by Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA) at 1 site in Netherlands.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 9 inclusion and 22 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 10 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Netherlands. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Tick feeding: tick weight (time frame: From the start of the tick challenge until feeding to repletion of the ticks (max 10 days)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 10 Jun 2026; AzTrials last refreshed its copy on 7 Nov 2026.