LeptospirosisNEUTROLEPTO-NCNCT07611591
Ex Vivo Study of Leukocyte Responses in the Blood of Patients With Leptospirosis and ex Vivo Testing of a New Host-targeted Therapeutic Strategy to Restore Phagocytosis of Leptospira
An observational study of Leptospirosis and Jarisch Herxheimer Reaction, run by Institut Pasteur.
Trial summary
Leptospirosis is a neglected zoonosis caused by pathogenic spirochetes of the genus *Leptospira*, occurring mainly in humid tropical and subtropical regions. With over one million cases and ~60,000 deaths annually, it is among the most dangerous bacterial zoonoses worldwide. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Leptospirosis, Jarisch Herxheimer Reaction
- What is being tested?
- 24 ml blood sample at H0 and 16 ml blood sample at H3
- How many people
- 70 participants
- Where
- No sites listed yet
- Study dates
- 1 Dec 2026to 1 Dec 2029
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
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 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Individuals presenting at the emergency department of the Territorial Hospital Center of New Caledonia with signs and symptoms of leptospirosis:
Who may be able to join
- Be of legal age (18 years or older at the time of enrollment),
- Be capable of understanding and providing informed consent,
- Have received information and provided written consent,
- Be enrolled in a social security program.
- Be suspected of having leptospirosis
Who cannot join
- With a chronic inflammatory disease,
- Whose health condition is incompatible with additional blood draws totaling 40 ml,
- Receiving concomitant treatment with antibiotics and/or anti-inflammatory drugs, or undergoing medical treatment incompatible with the study's objectives,
- Pregnant or breastfeeding women.
- Hospitalized or having undergone surgery within the previous 7 days
About this study
Leptospirosis is a neglected zoonosis caused by pathogenic spirochetes of the genus *Leptospira*, occurring mainly in humid tropical and subtropical regions. With over one million cases and ~60,000 deaths annually, it is among the most dangerous bacterial zoonoses worldwide. Its nonspecific onset-fever, headache, myalgia-mimics influenza, dengue, and other acute febrile illnesses, making diagnosis difficult. Delayed antibiotic treatment can lead to severe forms (in ~10% of cases) characterized by hemorrhage and multi-organ failure. In 2023, New Caledonia reported 152 cases, with 85% hospitalized and a 2.6% mortality rate.
This study aims to characterize the human host response and improve patient management. *Leptospira* evades innate immunity, triggering a strong anti-inflammatory IL-10 response and potentially ineffective phagocytosis. However, the WHO-recommended β-lactam antibiotics induce a Jarisch-Herxheimer reaction (JHR)-an acute inflammatory response occurring within hours of treatment-in over 50% of patients (LEPJAR study, PMID:40986630), the impact of which on phagocytosis is unknown.The NEUTROLEPTO study will be conducted in New Caledonia (NC) in patients with or without leptospirosis. Clinical and biological data will be collected at the time of suspected infection and 3 hours after antibiotic administration. Specifically, immune responses will be assessed through cytokine profiling and blood cell phenotyping, as well as by transcriptome analysis of infected patients before and after antibiotic treatment.
Read the detailed description
The aim of the study is to compare the immune cell responses in the blood of patients hospitalized for leptospirosis with those of patients with another infection, before and 3 hours after antibiotic therapy.
Individuals presenting to the emergency department of the Territorial Hospital Center of New Caledonia with signs and symptoms of leptospirosis will be recruited:
-with a confirmed diagnosis of leptospirosis (Group 1),-
-with an infectious diagnosis other than leptospirosis (Group 2)
Blood and clinical data will be collected from all the participants.
- Conditions
- Leptospirosis, Jarisch Herxheimer Reaction
- Being tested
- 24 ml blood sample at H0, 16 ml blood sample at H3
- Keywords
- leptospirosis, Jarisch Herxheimer Reaction, Inflammation, ß-lactams antibiotics
- Medical subject headings
- Leptospirosis, Inflammation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
24 ml blood sample at H0Other
24 ml blood sample at H0
16 ml blood sample at H3Other
16 ml blood sample at H3
| Study group | Role | What they receive |
|---|---|---|
| Individuals with symptoms of leptospirosis with a confirmed diagnosis of leptospirosis | Not described Receives: Other: 24 ml blood sample at H0; Other: 16 ml blood sample at H3 | |
| Individuals with symptoms of leptospirosis with a diagnosis of an infection other than leptospirosis | Not described Receives: Other: 24 ml blood sample at H0; Other: 16 ml blood sample at H3 |
What is being measured
The primary outcome is the main question the study is designed to answer.
to compare the immune cell responses in the blood of patients hospitalized for leptospirosis with those of patients with another acute infection (MFA), both before and 3 hours after antibiotic treatment.
Flow cytometric phenotyping of different cell populations, as well as their activation markers and intracellular cytokines and measurement of cytokines using ELISA or LUMINEX in the blood (H0 at enrollment and H3, 3 hours after antibiotic administration) of individuals suspected of having leptospirosis
Measured: 3 years
Secondary outcomes (2)
Test certain innovative host-based strategies aimed at restoring phagocytic responses against Leptospira in the blood of patients with leptospirosis.response.
Conduct ex vivo killing assays using patient blood in the presence of preparations based on so-called "natural" immunoglobulins to test a new host-targeted therapeutic strategy against leptospirosis.
Measured: 3 years
Describe and characterise the Leptospira spp. strain
Measurement of bacterial load by PCR of the lipl32 gene, identification of the Leptospira spp. genogroup by bacterial DNA sequencing or other molecular biology methods (PCR) and/or of the serovar by MAT, sequencing of the bacterial mRNA.
Measured: 3 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 May 2026
- Study start1 Dec 2026 (estimated)
- Primary completion1 Dec 2029 (estimated)
- Study completion1 Dec 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for LeptospirosisStudies of the same condition, open and under way.
- More trials run by Institut PasteurThe 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
- Observational
- Observational model
- Case-control
- Time perspective
- Prospective
- Enrolment
- 70 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Institut Pasteur
- Sponsor type
- Industry (pharma, biotech, devices)
- Collaborators
- Centre Hospitalier Territorial Gaston- Bourret
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07611591
- Sponsor's protocol ID
- 2025-146
- Other IDs
- 2025-A02688-41
- Acronym
- NEUTROLEPTO-NC
- Status last verified
- May 2026
- First submitted
- 21 May 2026
- Last updated
- 3 Nov 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 3 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Ex Vivo Study of Leukocyte Responses in the Blood of Patients With Leptospirosis and ex Vivo Testing of a New Host-targeted Therapeutic Strategy to Restore Phagocytosis of Leptospira
- ClinicalTrials.gov ID
- NCT07611591
- Acronym / sponsor ID
- NEUTROLEPTO-NC / 2025-146
- Conditions
- Leptospirosis, Jarisch Herxheimer Reaction
- Keywords
- leptospirosis, Jarisch Herxheimer Reaction, Inflammation, ß-lactams antibiotics
- Study type
- Observational
- Recruitment status
- Not yet recruiting
- Enrolment
- 70 participants (estimated)
- Lead sponsor
- Institut PasteurIndustry (pharma, biotech, devices)
- Collaborators
- Centre Hospitalier Territorial Gaston- Bourret
- Study start
- 1 Dec 2026 (estimated)
- Primary completion
- 1 Dec 2029 (estimated)
- Study completion
- 1 Dec 2029 (estimated)
- First posted
- 28 May 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.
Leptospirosis is a neglected zoonosis caused by pathogenic spirochetes of the genus *Leptospira*, occurring mainly in humid tropical and subtropical regions. With over one million cases and ~60,000 deaths annually, it is among the most dangerous bacterial zoonoses worldwide. Its nonspecific onset-fever, headache, myalgia-mimics influenza, dengue, and other acute febrile illnesses, making diagnosis difficult. Delayed antibiotic treatment can lead to severe forms (in ~10% of cases) characterized by hemorrhage and multi-organ failure. In 2023, New Caledonia reported 152 cases, with 85% hospitalized and a 2.6% mortality rate.
This study aims to characterize the human host response and improve patient management. *Leptospira* evades innate immunity, triggering a strong anti-inflammatory IL-10 response and potentially ineffective phagocytosis. However, the WHO-recommended β-lactam antibiotics induce a Jarisch-Herxheimer reaction (JHR)-an acute inflammatory response occurring within hours of treatment-in over 50% of patients (LEPJAR study, PMID:40986630), the impact of which on phagocytosis is unknown.The NEUTROLEPTO study will be conducted in New Caledonia (NC) in patients with or without leptospirosis. Clinical and biological data will be collected at the time of suspected infection and 3 hours after antibiotic administration. Specifically, immune responses will be assessed through cytokine profiling and blood cell phenotyping, as well as by transcriptome analysis of infected patients before and after antibiotic treatment.
Detailed description
The aim of the study is to compare the immune cell responses in the blood of patients hospitalized for leptospirosis with those of patients with another infection, before and 3 hours after antibiotic therapy.
Individuals presenting to the emergency department of the Territorial Hospital Center of New Caledonia with signs and symptoms of leptospirosis will be recruited:
-with a confirmed diagnosis of leptospirosis (Group 1),-
-with an infectious diagnosis other than leptospirosis (Group 2)
Blood and clinical data will be collected from all the participants.
Study design
- Observational model
- Case-control
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Individuals with symptoms of leptospirosis with a confirmed diagnosis of leptospirosis | – | Other: 24 ml blood sample at H0, Other: 16 ml blood sample at H3 |
| Individuals with symptoms of leptospirosis with a diagnosis of an infection other than leptospirosis | – | Other: 24 ml blood sample at H0, Other: 16 ml blood sample at H3 |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Individuals presenting at the emergency department of the Territorial Hospital Center of New Caledonia with signs and symptoms of leptospirosis:
Key inclusion criteria (5 listed)
- Be of legal age (18 years or older at the time of enrollment),
- Be capable of understanding and providing informed consent,
- Have received information and provided written consent,
- Be enrolled in a social security program.
- Be suspected of having leptospirosis
Key exclusion criteria (5 listed)
- With a chronic inflammatory disease,
- Whose health condition is incompatible with additional blood draws totaling 40 ml,
- Receiving concomitant treatment with antibiotics and/or anti-inflammatory drugs, or undergoing medical treatment incompatible with the study's objectives,
- Pregnant or breastfeeding women.
- Hospitalized or having undergone surgery within the previous 7 days
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 |
|---|---|---|
| 24 ml blood sample at H024 ml blood sample at H0 | Other | Individuals with symptoms of leptospirosis with a confirmed diagnosis of leptospirosis, Individuals with symptoms of leptospirosis with a diagnosis of an infection other than leptospirosis |
| 16 ml blood sample at H316 ml blood sample at H3 | Other | Individuals with symptoms of leptospirosis with a confirmed diagnosis of leptospirosis, Individuals with symptoms of leptospirosis with a diagnosis of an infection other than leptospirosis |
Primary outcome
to compare the immune cell responses in the blood of patients hospitalized for leptospirosis with those of patients with another acute infection (MFA), both before and 3 hours after antibiotic treatment.
Time frame: 3 years
Flow cytometric phenotyping of different cell populations, as well as their activation markers and intracellular cytokines and measurement of cytokines using ELISA or LUMINEX in the blood (H0 at enrollment and H3, 3 hours after antibiotic administration) of individuals suspected of having leptospirosis
2 secondary outcomes
Test certain innovative host-based strategies aimed at restoring phagocytic responses against Leptospira in the blood of patients with leptospirosis.response.
Time frame: 3 years
Describe and characterise the Leptospira spp. strain
Time frame: 3 years
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Nov 2026.
- Individual participant dataSharing planned: No
Related trials for Leptospirosis
Not yet recruitingObservational study
Assessment of the Risk of Zoonotic Infections in Prisons in French Guiana
Q Fever, Leptospirosis
Not yet recruitingPhase 4
These Studies That Evaluated the Efficacy of Antibiotics for Leptospirosis Treatment.
Leptospirosis, Chemoprophylaxis
Recruiting
Leptospirosis Care Bundle Study
Leptospirosis
Active, not recruiting
Cohort of Hospitalized Patients Suspected of Leptospirosis
Leptospirosis
RecruitingPhase 2
Preventive Strategies for Early and Late Complications of Leptospirosis
Leptospirosis
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.
The record lists no contact. Use the official record to reach the sponsor.
Questions about this trial
What is this clinical trial studying?
An observational study of Leptospirosis and Jarisch Herxheimer Reaction, run by Institut Pasteur.
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 5 inclusion and 5 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: opening soon, as of the sponsor's last update on 3 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
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?
This study is still under way. Results are not available in the source record yet.
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?
to compare the immune cell responses in the blood of patients hospitalized for leptospirosis with those of patients with another acute infection (MFA), both before and 3 hours after antibiotic treatment. (time frame: 3 years). 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 3 Nov 2026.