CompletedInterventional

A study testing the safety and practicality of infecting healthy UK adults with malaria to understand how the parasite grows and how the body responds

Malaria is a serious illness spread by mosquito bites. One common parasite, Plasmodium vivax, can hide asleep in the liver and cause repeat bouts of illness months or even years later. In fact, most infections from this bug are repeat flare-ups. In this UK study, doctors at the Oxford Vaccine Group are testing how safely they can study these relapses in volunteers. Healthy participants aged 18 to 45 will travel to the Netherlands to be bitten by infected mosquitoes in a strictly controlled setting. Doctors will carefully monitor volunteers back in the UK and treat each flare-up with standard antimalarial tablets. At the end of the study, everyone receives medicine to clear any sleeping parasites from their liver completely. While taking part offers no direct personal health gain, it creates a crucial testing ground for future vaccines and cures.

At a glance

Status

Completed

Sponsor

University of Oxford

Enrolment target

Start

13 Jan 2025

Estimated completion

12 Mar 2025

Specialty: Infection, Primary sub-specialty: Tropical Medicine; Health Category: Infection

What is this study about?

Malaria is a major global infection caused by tiny parasites spread through mosquito bites. It causes flu-like symptoms such as high fever, headache, and body aches. While most malaria is easily treated, one widespread type called Plasmodium vivax has a sneaky trick: it leaves 'sleeping' parasites in the liver. These dormant bugs can wake up months later, triggering repeat bouts of illness known as relapses.

Because around 80% to 90% of cases with this parasite are relapses, scientists urgently need better treatments and vaccines. To test whether new medicines work, doctors first need to prove that they can safely track these relapses in a clinical setting. In this study, known as a human challenge trial, healthy volunteers are deliberately exposed to the parasite under tightly controlled, expert supervision.

Volunteers are monitored very closely, and every time the parasite shows up, it is immediately cleared with tablets. Once the study ends, volunteers take a final medication to remove any hidden liver parasites for good. Proving this study model works will pave the way for testing brand-new vaccines and life-saving medicines to help wipe out relapsing malaria worldwide.

Key takeaways

Healthy UK adults aged 18 to 45 can help researchers study relapsing malaria.
Volunteers are safely exposed to malaria through mosquito bites in a controlled laboratory setting.
All malaria episodes during the trial are treated quickly with proven antimalarial tablets.
A final medicine clears any sleeping parasites from the liver to prevent future infections.
The results will help scientists test and develop new malaria vaccines and treatments.

Who may be eligible?

This trial is open to healthy men and women aged 18 to 45 who have never had malaria before. Because safety is the top priority, volunteers must have healthy blood without inherited conditions like sickle cell trait or G6PD deficiency, which could affect how malaria or the study medicines work in the body.

You will need to live near Oxford or be able to travel to the Oxford clinic easily, as well as stay within 1 to 2 hours of an NHS hospital on the UK mainland. You must also have a valid passport to travel to the Netherlands for the mosquito bite challenge, carry a mobile phone so the team can reach you 24/7, and be willing to pause donating blood for at least three years afterwards. Those who can become pregnant must agree to use effective contraception.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you a healthy adult aged between 18 and 45?
Have you never had malaria before?
Can you easily travel to Oxford and take a short trip to the Netherlands?
Can you stay within 1 to 2 hours of an NHS hospital and be reachable by phone 24/7?
Are you willing to use reliable contraception and pause blood donations for three years?

Answer every question to see your result.

What does participation involve?

Taking part involves around 7.5 months of active clinic visits, followed by short email questionnaires for up to four years. First, you attend a screening check in Oxford to make sure you are safe to join. Next, you travel to the Netherlands for a short visit where you are exposed to malaria-carrying mosquitoes in a sterile laboratory. Back in the UK, you will attend regular appointments for health reviews and blood tests. Whenever the malaria parasite causes symptoms over the next six months, doctors will give you proven antimalarial tablets to clear the illness quickly. At month seven, you will take a medicine called primaquine to clear any sleeping parasites from your liver. Finally, you will complete periodic email check-ins so doctors can confirm you remain healthy.

Potential risks and benefits

Taking part will not give you any direct health benefit, but your involvement will help scientists test new treatments that could protect millions of people. The main risks include typical malaria symptoms like fever, chills, and aching muscles, as well as temporary itching or redness from mosquito bites and minor bruising from blood tests. Malaria can become serious if left untreated, so you must attend all appointments, take all medicines as advised, and stay in close contact with the team. Taking part is completely voluntary, and you can withdraw at any time, though for your own safety you would still need to complete the full medicine course to clear the parasite.

Locations (1)

Oxford Vaccine Group
Approximate
Oxford, England

Common questions

Will I get very ill with malaria during the trial?

You may experience mild to moderate flu-like symptoms such as a fever, chills, or headache. The medical team watches you continuously and provides effective antimalarial medicine at the first sign of infection so it does not become dangerous.

Why do I have to travel to the Netherlands?

The specialised, sterile laboratory equipped to safely raise the infected mosquitoes and carry out the controlled bites is located in the Netherlands. The study team arranges and guides this trip.

How is the infection cleared completely from my body?

At the end of the active study period, you will receive a standard medication called primaquine. This clears out any dormant parasites hiding in your liver so the infection cannot return.

Why can't I donate blood after the study?

UK blood donor safety rules require anyone exposed to malaria or certain antimalarial drugs to wait at least three years before donating blood, ensuring donor blood remains safe for NHS patients.

Can I leave the study if I change my mind?

Yes, taking part is entirely voluntary. However, if you leave after being exposed to malaria, you will still need to complete the course of antimalarial tablets to ensure the parasite is fully cleared from your body.

How to find out more

Rachel Cowan-Jansen

info@OVG.ox.ac.uk +44 (0)1865 611400 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.