Actively Recruiting
Clinical Study to Assess Minimum Mosquito Bites for P. Vivax Infection in Thai Adults
Led by University of Oxford · Updated on 2026-03-27
24
Participants Needed
1
Research Sites
82 weeks
Total Duration
On this page
Sponsors
U
University of Oxford
Lead Sponsor
M
Mahidol University
Collaborating Sponsor
AI-Summary
What this Trial Is About
This study is a human challenge study to assess the minimum infective mosquito bite dose in a controlled human malaria Infection (via P. vivax sporozites) in healthy volunteers. The results will inform the development of a P. vivax mosquito-delivered CHMI trial platform, supporting safer and more accurate vaccine efficacy assessments. Conducting the trial in individuals genetically and immunologically similar to the target population will also enhance the relevance of findings to real-world endemic settings. 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.
CONDITIONS
Official Title
Clinical Study to Assess Minimum Mosquito Bites for P. Vivax Infection in Thai Adults
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Healthy adults aged 20 to 55 years weighing more than 50 kg
- No recent malaria infection
- Red blood cells positive for Duffy antigen/chemokine receptor (DARC)
- CYP2D6 alleles consistent with normal metaboliser status
- Normal Glucose-6-phosphate dehydrogenase (G6PD) enzyme activity by WHO definition
- Women must use continuous effective contraception during the study and for 3 months post-challenge
- Agreement to avoid blood donation during the study and for 1 year afterward
- Willingness to take curative antimalarial treatment after challenge
- Willingness to be hospitalized for monitoring until treatment completion and symptom improvement
- Willingness to reside in Bangkok during clinical study period
- Willingness to be followed for 1 year after treatment starts
- Reachable by mobile phone 24/7 during challenge and treatment
- Ability to read and write Thai and answer informed consent questions correctly
- Provided written informed consent
- Low cardiovascular risk (less than 10% in 10 years per Thai NCD Division)
- At least a bachelor's degree education level
You will not qualify if you...
- History of clinical malaria
- Positive malaria PCR, film, or serology indicating recent exposure
- History of severe allergy to mosquito bites
- G6PD mutation
- Any physical or psychological medical condition posing risk or interfering with study results
- Chronic disease or chronic medication use
- Planned travel outside Bangkok from challenge until 3 months post-challenge
- Use of systemic antibiotics with antimalarial activity within 30 days before challenge
- Use of immunoglobulins or blood products within 1 year before enrollment
- Receipt of investigational products or vaccines within 30 days before or planned during study
- Prior investigational vaccine likely to affect trial data or parasite
- Immunosuppressive or immunodeficient conditions including HIV, asplenia, or recurrent severe infections
- Use of immunosuppressants within 6 months before enrollment (except inhaled or topical steroids)
- History of allergic diseases or reactions worsened by malaria
- Pregnancy, lactation, or planning pregnancy within 1 year post-challenge
- Contraindications to antimalarial treatments used in study
- Use of medications interacting with study antimalarials or prolonging QT interval
- Family history of early cardiac disease or congenital QT prolongation
- Clinical conditions known to prolong QT interval or history of cardiac arrhythmia
- QTc interval ≥ 450 ms on screening ECG
- History or suspicion of alcohol or drug abuse
- Participation in another clinical study during this study
- Abnormal laboratory safety values including elevated ALT, creatinine, abnormal calcium/magnesium, low hemoglobin, or high HbA1C
- Thalassemia or hemoglobinopathies
- Positive tests for hepatitis B, hepatitis C, HIV, syphilis, or HTLV I/II
AI-Screening
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Trial Site Locations
Total: 1 location
1
Faculty of Tropical Medicine, Mahidol University
Bangkok, Thailand, 10400
Actively Recruiting
Research Team
N
Nicholas Day, MD
CONTACT
J
Jetsumon Sattabongkot Prachumsri, Ph.D
CONTACT
How is the study designed?
Study Type
INTERVENTIONAL
Masking
NONE
Allocation
NA
Model
SEQUENTIAL
Primary Purpose
OTHER
Number of Arms
1
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