Actively Recruiting

Phase Not Applicable
Age: 20Years - 55Years
All Genders
Healthy Volunteers
ID05071079

A Clinical Study to Assess the Safety and Feasibility of Controlled Blood-stage Plasmodium Vivax Human Malaria Infection Through Experimental Inoculation of Cryopreserved Infected Erythrocytes in Healthy Thai Adults

Led by University of Oxford · Updated on 2026-01-12

48

Participants Needed

1

Research Sites

N/A

Total Duration

On this page

Sponsors

U

University of Oxford

Lead Sponsor

W

Wellcome Trust

Collaborating Sponsor

AI-Summary

What this Trial Is About

Researchers are evaluating the safety and feasibility of a controlled human Plasmodium vivax malaria infection (CHMI) in healthy adult Thai volunteers. This study aims to find the best dose of cryopreserved P. vivax infected red blood cells for future studies by experimentally injecting these infected cells into volunteers. The study involves up to 48 participants, who will be closely monitored in a hospital setting, with the goal of understanding the infection process and treatment responses. Participants will receive one of four doses of infected red blood cells, ranging from a whole vial to diluted amounts, administered by injection. Each dose will be tested in groups of volunteers to identify which dose reliably produces infection. The study includes a screening period, a challenge day for infection, a monitoring phase until treatment criteria are met, and a follow-up period lasting one year after treatment. Volunteers will be admitted to the hospital for close monitoring, including daily health checks and blood tests to detect malaria parasites and assess immune responses. After infection is confirmed, blood samples will be taken twice daily until participants meet treatment criteria, at which point antimalarial drugs will be given. Follow-up visits will occur over the next year to monitor health, immune response, and possible parasite transmission. Safety and infection outcomes will be analyzed throughout the study period.

CONDITIONS

Brief Title

A Controlled Human Vivax Malaria Infection Study Through Inoculation of Infected Erythrocytes

Who Can Participate

Age: 20Years - 55Years
All Genders
Healthy Volunteers

Eligibility Criteria

Eligible

You may qualify if you...

  • Healthy Thai adult aged 20 to 55 years with weight at least 50 kg
  • Red blood cells positive for the Duffy antigen/chemokine receptor (DARC)
  • Women must practice continuous effective contraception during the study and for 3 months post-challenge
  • Received at least two doses of WHO-approved COVID-19 vaccines
  • Agree to refrain from blood donation during the study and for 1 year after starting antimalarial treatment
  • Willing to be admitted to the hospital for monitoring until antimalarial treatment is completed
  • Willing to take curative antimalarial treatment following challenge
  • Willing to live in Bangkok or nearby for 2 months after treatment
  • Able to read and write in Thai
  • Provide written informed consent and answer all informed consent questions correctly
  • Have at least an undergraduate degree
Not Eligible

You will not qualify if you...

  • Positive malaria test by qPCR or blood film
  • Any physical or psychological medical condition increasing risk or interfering with study results
  • Chronic disease or chronic medication use
  • Use of systemic antibiotics with antimalarial activity in 30 days before challenge
  • Use of immunoglobulins or blood products in the past year
  • Receipt of investigational products or vaccines within 30 days before enrollment
  • Prior investigational vaccine likely affecting trial interpretation
  • Immunosuppressive or immunodeficient states, including HIV or history of splenectomy
  • Immunosuppressant medication use within 6 months before enrollment (inhaled/topical steroids allowed)
  • History of allergic reactions likely worsened by malaria
  • Pregnancy, breastfeeding, or planning pregnancy during the study
  • Contraindications to antimalarial drugs used in study
  • Use of medications interacting with antimalarial drugs used
  • Positive family history of early cardiac disease
  • History of cardiac arrhythmia or clinically relevant bradycardia
  • Family history of congenital QT prolongation or sudden death
  • Conditions or medications known to prolong QT interval
  • ECG showing QTc interval ≥ 450 ms
  • History or suspicion of alcohol or drug abuse
  • Participation in another clinical study during the study period
  • Hemoglobin below 11 g/dL
  • Positive hepatitis B surface antigen or hepatitis C seropositive
  • Abnormal liver enzymes or kidney function tests beyond defined limits
  • Rhesus negative blood group
  • Blood incompatibility with inoculum
  • Positive COVID-19 test by RT-PCR

AI-Screening

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Your Study Journey

Screening

Duration - 2 to 4 weeks

Participants are screened for eligibility to participate in the trial.

1 screening and enrollment visit (in-person)

Challenge

Duration - About 2 weeks until reaching malarial treatment criteria

Participants receive a controlled inoculation of malaria parasitized red blood cells in one of four different dose levels to assess infection development.

Daily visits starting Day 1 after challenge until malaria qPCR becomes positive, then twice daily visits until antimalarial treatment initiation

Antimalarial Treatment and Hospital Monitoring

Duration - Up to 3 weeks post-challenge depending on infection status

Participants receive antimalarial treatment once infection criteria are met and are monitored daily in the hospital until clinical recovery and parasite clearance.

Daily visits for blood tests until clinical recovery and two consecutive negative malaria blood films

Follow-up

Duration - 1 year post antimalarial treatment initiation

Participants attend outpatient visits after hospital discharge for continued monitoring of health status, malaria parasite presence, immune response, and other safety assessments.

Outpatient visits on days 7, 28, 60, 90, 180, and 1 year post-treatment

Trial Site Locations

Total: 1 location

1

Faculty of Tropical Medicine

Bangkok, Thailand, 10400

Actively Recruiting

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Research Team

N

Nicholas Day, MD

J

Jetsumon Sattabongkot Prachumsri, Ph.D

How is the study designed?

Study Type

INTERVENTIONAL

Masking

TRIPLE

Allocation

RANDOMIZED

Model

PARALLEL

Primary Purpose

OTHER

Number of Arms

4

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Published Research Related To This Trial

Implications of current therapeutic restrictions for primaquine and tafenoquine in the radical cure of vivax malaria.

James Watson, Walter R J Taylor, Germana Bancone...

https://pubmed.ncbi.nlm.nih.gov/29677199