Scientists at the University of Oxford have initiated a "malaria challenge study" to delve into the long-term effects and mechanisms behind relapsing infections of Plasmodium vivax malaria. The study, known as BIO-006, involves deliberately infecting healthy volunteers with malaria to closely monitor their immune responses and the dynamics of relapses over an extended period.
Study Design and Objectives
Five healthy individuals, aged 18 to 45, will travel to the Radboud University Medical Centre in Nijmegen, Netherlands, where they will be exposed to mosquitoes carrying the Plasmodium vivax parasite. Following the mosquito bites, participants will return to the Centre for Clinical Vaccinology and Tropical Medicine in Oxford for comprehensive monitoring.
The primary objective of this study is to gain a deeper understanding of how the immune system responds to relapses of P. vivax malaria. According to Professor Angela Minassian, chief investigator for the trial from the University of Oxford, "This proof-of-concept study is the first of its kind to safely introduce relapsing vivax malaria infections in healthy volunteers under controlled research conditions." The research aims to identify potential targets for novel vaccines or drugs that could eliminate the parasite from the liver, thereby preventing relapses.
Monitoring and Treatment
Participants will undergo daily monitoring for the first six days via phone, followed by in-person assessments from day seven onwards. Upon detection of malaria in the blood, participants will promptly receive anti-malarial medication to manage the acute infection. However, this initial treatment will not eliminate the dormant parasites in the liver, allowing scientists to observe and study relapsing malaria infections over the subsequent six months.
During this period, participants will attend fortnightly check-ups and have access to 24/7 medical support to address any symptoms indicative of a relapse. Any relapse infections will be treated with anti-malarial medication. At the end of the six-month study period, all participants will receive anti-malarial tablets, including Primaquine, to clear any remaining dormant parasites from the liver. They will then be followed up for an additional five years to monitor for any unexpected relapses.
Significance and Impact
Plasmodium vivax malaria is characterized by its ability to remain dormant in the liver, leading to relapsing infections months or even years after the initial infection. These relapses contribute significantly to the global burden of malaria, particularly in adults and children. Professor Minassian notes that "more than 80% of vivax malaria globally is due to relapsing infections and they cause significant illness in both adults and children in many parts of the world."
This malaria challenge study represents a critical step towards developing more effective strategies to combat P. vivax malaria. By creating a controlled model of relapsing infection, researchers can evaluate novel interventions aimed at eliminating the parasite from the liver and preventing future relapses. The success of this study could transform the approach to combating this challenging disease, offering hope for more effective prevention and treatment strategies.
