Plasmodium Vivax InfectionMIST1NCT04083508
Vivax Malaria Human Infection Studies in Thailand
A study testing Mosquito bites in people with Plasmodium Vivax Infection, run by University of Oxford at 1 site in Thailand.
Trial summary
This study is a human challenge study to assess the feasibility and safety of controlled human malaria infection (via P. vivax sporozites) in healthy volunteers, and to develop a bank of P. vivax-infected blood for use in future controlled human P. vivax malaria infection studies. Read more about this study
- Who is it for?
- Ages 20 to 55 yearsHealthy volunteers can take part
- Conditions the study is for
- Plasmodium Vivax Infection
- What is being tested?
- Mosquito bites
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 5 participants
- Where
- 1 siteThailand
- Study dates
- 5 Oct 2020to 12 Sep 2025
- 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 20 to 55 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Healthy adult aged 20 to 55 years with weight more than 50 kg.
- Blood group O.
- Red blood cells positive for the Duffy antigen/chemokine receptor (DARC).
- CYP2D6 alleles consistent with normal metaboliser status
- Normal blood levels of Glucose-6-phosphate dehydrogenase (G6PDH) by the WHO definition.
- COVID-19 vaccination at least two doses of COVID-19 vaccine(s) approved by WHO.
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- Agree to practice continuous effective contraception for the duration of study period until 3 months post-challenge.
- Agreement to refrain from blood donation during the course of the study and for 1 year after the end of their involvement in the study.
- Willing to take a curative antimalarial regimen following challenge.
- Willing to be admitted in the Hospital for Tropical Diseases for blood donation and clinical monitoring, until antimalarial treatment is completed and their symptoms are settling.
- Willing to reside in Bangkok for the duration of the study, until all antimalarial treatment has been completed.
- Reachable (24/7) by mobile phone during the period between challenge CHMI and completion of all antimalarial treatment.
- Able to read and write in Thai and able to answer ALL questions on the informed consent questionnaire correctly.
- Provided written informed consent to participate in the trial.
- Educational level: has at least an undergraduate degree.
- Cardiovascular risk assessment is low (less than 10% in the next 10 years according to the cardiovascular risk assessment from Thai NCD Division, DDC, MoPH (2016)
Who cannot join
- History of clinical malaria.
- Positive malaria PCR OR malaria film OR malaria serology (recent exposure)
- History of severe allergy to mosquito bite
- Presence of any medical condition (either physical or psychological) which in the judgment of the investigator would place the participant at undue risk or interfere with the results of the study (e.g. serious underlying cardiac, renal, hepatic or neurological disease; severe malnutrition; congenital defects or febrile condition)
- Presence of chronic disease or chronically use of medication.
- Plan to travel outside of Bangkok within the period of challenge until 3 months after.
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- Use of systemic antibiotics with known antimalarial activity in the 30 days before challenge (e.g. trimethoprim-sulfamethoxazole, doxycycline, tetracycline, clindamycin, erythromycin, fluoroquinolones and azithromycin).
- Use of immunoglobulins or blood products (e.g. blood transfusion) at any time in the 1 year preceding enrolment.
- Venipuncture unlikely to allow blood donation according to the protocol as determined by the investigator.
- Receipt of an investigational product or any vaccine in the 30 days preceding enrolment (D0), or planned receipt during the study period.
- Prior receipt of an investigational vaccine likely to impact on interpretation of the trial data or the P. vivax parasite as assessed by the Investigator.
- Any confirmed or suspected immunosuppressive or immunodeficient state, including HIV infection, asplenia, history of splenectomy, recurrent, severe infections, and chronic infection.
- Immunosuppressant medication within the past 6 months preceding enrolment (D0) (inhaled and topical steroids are allowed).
- History of allergic disease or reactions likely to be exacerbated by malaria infection.
- Female participant who is pregnant, lactating or planning pregnancy during the course of the study.
- Contraindications to the use of antimalarial treatment (e.g. chloroquine or primaquine or atovaquone / proguanil, DHA piperaquine).
- Use of medications known to have a potentially clinically significant interaction with antimalarial drug that will be used in this study (chloroquine or primaquine or atovaquone / proguanil, DHA/ piperaquine).
- Use of medications known to cause prolongation of the QT interval as state in the section of prohibited drugs that may have effect on prolongation of the QT interval.
- Known existing positive family history in both 1st AND 2nd degree relatives < 50 years old for cardiac disease.
- Family history of congenital QT prolongation or sudden death.
- Any clinical condition known to prolong the QT interval.
- History of cardiac arrhythmia, including clinically relevant bradycardia.
- Screening ECG demonstrates a QTc interval ≥ 450 ms
- Suspected or known or history of alcohol abuse
- Suspected or known or history of drug abuse.
- Concurrently participating in another clinical study, at any time during the study period.
- Haemoglobin < 13 g/dL in male, < 12g/dL in female (Thai Red Cross).
- Finding on safety laboratory values as defined below:
- AST > 40 U/L for male, and > 32 U/L for female (upper normal range), or
- ALT > 41 U/L for male, and > 33 U/L for female (upper normal range), or
- Total Bilirubin > 1.2 mg/dL, (upper normal range), or
- Creatinine (Cr) > 1.17 mg/dL for male, and > 0.95 mg/dL for female (upper normal range), or
- Abnormalities corrected calcium and magnesium blood levels, or
- Fasting blood sugar (FBS) > 100 mg/dL
- Thalassaemia disease or haemoglobinopathies.
- Positive for a blood borne or vector borne infectious disease (HIVI-II, HBV, HCV, Dengue, Zika, Chikungunya, Filariasis, JE, and malaria antigen, Anti HTLVI and Anti-HTLVII antibody, Syphilis test (TPHA)
- Positive for COVID-19 testing as diagnosed by RT-PCR
Trial locations and contacts
1 site in 1 country.
About this study
Official title: A Clinical Study to Assess the Feasibility of a Controlled Human Plasmodium Vivax Malaria Infection Model Through Sporozoite Infection in Thai Adults
This study is a human challenge study to assess the feasibility and safety of controlled human malaria infection (via P. vivax sporozites) in healthy volunteers, and to develop a bank of P. vivax-infected blood for use in future controlled human P. vivax malaria infection studies. Additional objectives are to obtain data on host immune response to P. vivax infection and pre-treatment gametocytaemia.
This study is funded by the UK Wellcome Trust. The grant reference number are Oxford/MORU: 212336/Z/18/Z and 212336/Z/18/A, and Mahidol University: 212336/A/18/Z and 212336/A/18/A.
Read the detailed description
Six healthy, malaria-naïve Thai adults, aged between 20 and 55 years will be recruited at the Medical Therapeutics Unit (MTU) in the Hospital for Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok. The overall period of participation will be 15 months: a 3-month screening process prior to the Day 0 challenge, followed by 1 year after challenge. All inclusion and exclusion criteria will be checked to ensure eligibility criteria have been met prior to Day 0.
Volunteers will be admitted as inpatients to the CTU on Day -1 ( a day prior to the challenge day). Challenge (bites from 5 infected mosquitoes) will be administered at the Insectarium unit, Department of Entomology, Faculty of Tropical Medicine, Mahidol University. The infected mosquitoes will be prepared by the Malaria Vivax Research unit (MVRU, Faculty of Tropical Medicine, Mahidol University). Following successful feeding by the infectious mosquitoes, volunteers will be monitored daily as inpatients for parasitemia and clinical presentation of malaria infection (Days 1-5).
Beginning on Day 6, volunteers will be assessed twice a day and, at a timepoint that will depend upon the level of parasitaemia and/or degree of the volunteer's symptoms, up to 250 mL of blood will be drawn and then antimalarial treatment will be prescribed. The standard malaria radical cure according to standardguideline will be chloroquine, followed by direct observed of oral primaquine (PQ) 30 mg once daily until a total dose of 10 mg/kg is achieved. Upon confirmation of clinical recovery, completion of chloroquine treatment and laboratory absence of infection, volunteers will be discharged and followed daily as outpatients through completion of oral primoquine therapy.
After completion of antimalarial therapy, all volunteers will continue to be followed for 1 year after Day 0:
- Outpatient CTU visits on Days 28,60, 90, 180, and 365 post-challenge. Procedures to be performed during these visits will include review of symptom diary cards, medical history, physical examination and assessment of adverse events. Blood samples will also be obtained to detect malaria antigens and assess immune response.
- Volunteers will be contacted by study staff every 2 weeks between visits until Day 365, to inquire for malaria symptoms or other adverse events.
- Conditions
- Plasmodium Vivax Infection
- Being tested
- Mosquito bites
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Mosquito bitesOther
Successful feeding of 5 infected P. vivax mosquitoes
| Study group | Role | What they receive |
|---|---|---|
| Malaria challenge | Experimental | Malaria Sporozoite Challenge by mosquito bites. Receives: Other: Mosquito bites |
What is being measured
The primary outcome is the main question the study is designed to answer.
Successful infection of controlled P. vivax sporozoite human challenge
Measured by successful infection (development of detectable persistent parasitaemia) and malaria clinical symptoms, if any, after mosquito bite malaria sporozoite challenge
Measured: up to 21 days after challenge
(Serious) Adverse Event(s) occurrences of controlled P. vivax sporozoite human challenge
Measured by (S)AE(s) occurrences after mosquito bite malaria sporozoite challenge.
Measured: up to 90 days after challenge
Collection and freezing down of up to 250 mL P. vivax-infected blood from each of the 6 volunteers.
measured by successful collection and freezing down of up to 250 mL P. vivax-infected blood from each of the 6 volunteers.
Measured: up to 21 days after challenge
Secondary outcomes (3)
Cellular Immune response to primary P. vivax infection.
immune cells including Innate and adaptive immune cells react and express during the PV infection (profile and frequency)
Measured: up to 1 year after challenge
Humoral Immune response to primary P. vivax infection.
Immune cells defense PV antigen by determining the level of antibody response and inflammatory cytokine
Measured: up to 1 year after challenge
Gametocytaemia following primary P. vivax infection delivered by the mosquito bite
Gametocyte qPCR following primary P. vivax infection delivered by the mosquito bite
Measured: up to 1 year after challenge
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Sep 2019
- Study start5 Oct 2020
- Primary completion12 Sep 2025
- Study completion12 Sep 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Plasmodium Vivax InfectionStudies of the same condition, open and under way.
- More trials run by University of OxfordThe 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
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Mosquito-bite controlled human challenge infection
- Masking
- None (open label)
- Enrolment
- 5 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Oxford
- Sponsor type
- University, hospital or other
- Collaborators
- Mahidol University
- Responsible party
- Sponsor
- Investigators
- Nicholas Day, MD, Principal investigator, University of Oxford
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04083508
- Sponsor's protocol ID
- MAL19002
- Acronym
- MIST1
- Status last verified
- Jun 2026
- First submitted
- 5 Sep 2019
- Last updated
- 7 Jul 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: With participant's consent, suitably anonymised clinical data and results from blood analyses stored in the database may be shared according to the terms defined in the MORU data sharing policy with other researchers to use in the future.
Publications
Naemiratch B, Kulpijit N, Ruangkajorn S, Day NPJ, Prachumsri J, Cheah PY. Experiences, perceptions and ethical considerations of the malaria infection study in Thailand. BMC Med Ethics. 2025 Jan 28;26(1):14. doi: 10.1186/s12910-024-01160-7.
PubMed 39875955
Study at a glance
From the registry record, last updated by the sponsor on 7 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Clinical Study to Assess the Feasibility of a Controlled Human Plasmodium Vivax Malaria Infection Model Through Sporozoite Infection in Thai Adults
- ClinicalTrials.gov ID
- NCT04083508
- Acronym / sponsor ID
- MIST1 / MAL19002
- Conditions
- Plasmodium Vivax Infection
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 5 participants (actual)
- Lead sponsor
- University of OxfordUniversity, hospital or other
- Collaborators
- Mahidol University
- Study start
- 5 Oct 2020 (actual)
- Primary completion
- 12 Sep 2025 (actual)
- Study completion
- 12 Sep 2025 (actual)
- First posted
- 10 Sep 2019 (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.
This study is a human challenge study to assess the feasibility and safety of controlled human malaria infection (via P. vivax sporozites) in healthy volunteers, and to develop a bank of P. vivax-infected blood for use in future controlled human P. vivax malaria infection studies. Additional objectives are to obtain data on host immune response to P. vivax infection and pre-treatment gametocytaemia.
This study is funded by the UK Wellcome Trust. The grant reference number are Oxford/MORU: 212336/Z/18/Z and 212336/Z/18/A, and Mahidol University: 212336/A/18/Z and 212336/A/18/A.
Detailed description
Six healthy, malaria-naïve Thai adults, aged between 20 and 55 years will be recruited at the Medical Therapeutics Unit (MTU) in the Hospital for Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok. The overall period of participation will be 15 months: a 3-month screening process prior to the Day 0 challenge, followed by 1 year after challenge. All inclusion and exclusion criteria will be checked to ensure eligibility criteria have been met prior to Day 0.
Volunteers will be admitted as inpatients to the CTU on Day -1 ( a day prior to the challenge day). Challenge (bites from 5 infected mosquitoes) will be administered at the Insectarium unit, Department of Entomology, Faculty of Tropical Medicine, Mahidol University. The infected mosquitoes will be prepared by the Malaria Vivax Research unit (MVRU, Faculty of Tropical Medicine, Mahidol University). Following successful feeding by the infectious mosquitoes, volunteers will be monitored daily as inpatients for parasitemia and clinical presentation of malaria infection (Days 1-5).
Beginning on Day 6, volunteers will be assessed twice a day and, at a timepoint that will depend upon the level of parasitaemia and/or degree of the volunteer's symptoms, up to 250 mL of blood will be drawn and then antimalarial treatment will be prescribed. The standard malaria radical cure according to standardguideline will be chloroquine, followed by direct observed of oral primaquine (PQ) 30 mg once daily until a total dose of 10 mg/kg is achieved. Upon confirmation of clinical recovery, completion of chloroquine treatment and laboratory absence of infection, volunteers will be discharged and followed daily as outpatients through completion of oral primoquine therapy.
After completion of antimalarial therapy, all volunteers will continue to be followed for 1 year after Day 0:
- Outpatient CTU visits on Days 28,60, 90, 180, and 365 post-challenge. Procedures to be performed during these visits will include review of symptom diary cards, medical history, physical examination and assessment of adverse events. Blood samples will also be obtained to detect malaria antigens and assess immune response.
- Volunteers will be contacted by study staff every 2 weeks between visits until Day 365, to inquire for malaria symptoms or other adverse events.
Study design
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Mosquito-bite controlled human challenge infection
| Arm | Type | Receives |
|---|---|---|
| Malaria challenge | Experimental | Other: Mosquito bitesMalaria Sporozoite Challenge by mosquito bites. |
Who may qualify
- Ages
- 20 to 55 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (16 listed)
- Healthy adult aged 20 to 55 years with weight more than 50 kg.
- Blood group O.
- Red blood cells positive for the Duffy antigen/chemokine receptor (DARC).
- CYP2D6 alleles consistent with normal metaboliser status
- Normal blood levels of Glucose-6-phosphate dehydrogenase (G6PDH) by the WHO definition.
Key exclusion criteria (37 listed)
- History of clinical malaria.
- Positive malaria PCR OR malaria film OR malaria serology (recent exposure)
- History of severe allergy to mosquito bite
- Presence of any medical condition (either physical or psychological) which in the judgment of the investigator would place the participant at undue risk or interfere with the results of the study (e.g. serious underlying cardiac, renal, hepatic or neurological disease; severe malnutrition; congenital defects or febrile condition)
- Presence of chronic disease or chronically use of medication.
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 |
|---|---|---|
| Mosquito bitesSuccessful feeding of 5 infected P. vivax mosquitoes | Other | Malaria challenge |
Primary outcome
Successful infection of controlled P. vivax sporozoite human challenge
Time frame: up to 21 days after challenge
Measured by successful infection (development of detectable persistent parasitaemia) and malaria clinical symptoms, if any, after mosquito bite malaria sporozoite challenge
(Serious) Adverse Event(s) occurrences of controlled P. vivax sporozoite human challenge
Time frame: up to 90 days after challenge
Measured by (S)AE(s) occurrences after mosquito bite malaria sporozoite challenge.
Collection and freezing down of up to 250 mL P. vivax-infected blood from each of the 6 volunteers.
Time frame: up to 21 days after challenge
measured by successful collection and freezing down of up to 250 mL P. vivax-infected blood from each of the 6 volunteers.
3 secondary outcomes
Cellular Immune response to primary P. vivax infection.
Time frame: up to 1 year after challenge
Humoral Immune response to primary P. vivax infection.
Time frame: up to 1 year after challenge
Gametocytaemia following primary P. vivax infection delivered by the mosquito bite
Time frame: up to 1 year after 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 7 Jul 2026.
- Derived from this study: PubMed 39875955Naemiratch B, Kulpijit N, Ruangkajorn S, Day NPJ, Prachumsri J, Cheah PY. Experiences, perceptions and ethical considerations of the malaria infection study in Thailand. BMC Med Ethics. 2025 Jan 28;26(1):14. doi: 10.1186/s12910-024-01160-7.
- Individual participant dataSharing planned: Yes. With participant's consent, suitably anonymised clinical data and results from blood analyses stored in the database may be shared according to the terms defined in the MORU data sharing policy with other researchers to use in the future.
Related trials for Plasmodium Vivax Infection
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Three-arm Cluster Randomised Control Trial Evaluation of Guardian Spatial Emanator as a Complimentary Vector Control Tool in Papua New Guinea
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RecruitingPhase 1
Induced Blood-Stage Malaria in Healthy Malaria-Naive Adults to Assess the Safety and Infectivity of Plasmodium Vivax Challenge Agent and Evaluate Transmission in Mosquito Feeding Assays
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Safety and Immunogenicity of the Recombinant Malaria Vaccines in Healthy Adults Aged 18-50 Years
Malaria Vaccine
Not yet recruitingPhase 2
This is a Clinical Study to Assess Whether the Combination of SJ733 and Tafenoquine Will be a Safe and Rapidly Acting Anti-malarial for the Radical Cure of P. Vivax Malaria
Malaria, Malaria Vivax
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.
Nicholas Day, MD principal investigator
University of Oxford
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Mosquito bites in people with Plasmodium Vivax Infection, run by University of Oxford at 1 site in Thailand.
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 16 inclusion and 37 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 7 Jul 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 Thailand. 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?
Successful infection of controlled P. vivax sporozoite human challenge (time frame: up to 21 days after challenge). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04083508, which also lists 1 linked publication.
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 7 Jul 2026.