Playing with fire again: researchers aim to intentionally infect individuals with a deadly disease.

Researchers from the Oxford Vaccine Group are conducting a new study to gain a deeper understanding of Plasmodium vivax, a malaria species known for its ability to remain dormant in the liver and cause relapses of infection months or even years after the initial infection. To achieve this, five healthy volunteers will be sent to the Radboud University Medical Center in Nijmegen, Netherlands, where they will be bitten by mosquitoes carrying the parasite under controlled conditions, reports BBC.

The study, led by Professor Angela Minassian from the University of Oxford, marks the first instance of deliberately infecting healthy individuals with relapsing vivax malaria in a research setting. The aim of the research is to uncover key aspects of the parasite's relapsing nature and the immune system's response to these processes.

After the bites, participants will return to Oxford for thorough daily observation, and any signs of malaria in their blood will trigger immediate treatment with antimalarial medications, the scientists assured. However, these medications will not eliminate the dormant parasites in the liver stage, allowing researchers to study relapses over the next six months. During this period, participants will undergo regular check-ups, and they will receive 24/7 medical support should any symptoms arise.

Following this, all participants will receive treatment aimed at eradicating the dormant parasites and will be monitored for five years to rule out unforeseen relapses. Professor Minassian emphasized the importance of this study, noting that over 80% of Plasmodium vivax malaria cases worldwide are associated with relapsing infections. "Our work, if successful, will create a model for testing new vaccines or drugs capable of eradicating the parasite in the liver and completely halting relapses. This could fundamentally change our approaches to combating this complex disease," she stated.

The results obtained could pave the way for innovative treatment methods targeting the dormant phase of the parasite, which would be a significant step towards reducing the global burden of malaria, the authors believe. According to the World Health Organization (WHO), malaria caused by Plasmodium parasites transmitted through mosquito bites remains a serious global health issue, with over 200 million cases and more than 600,000 deaths reported annually.

While Plasmodium falciparum is the deadliest form, Plasmodium vivax poses particular challenges due to its ability to hide in the liver for extended periods and reactivate. This makes its eradication particularly difficult in endemic regions such as Southeast Asia and parts of South America. Current antimalarial drugs often fail to address these dormant liver stages, highlighting the urgent need for breakthroughs in prevention and treatment.

Controlled human malaria infection (CHMI) trials, like those the Oxford Vaccine Group intends to conduct, have played a crucial role in advancing malaria research over the years. Such trials allow scientists to study the disease under carefully controlled conditions, leading to accelerated development of vaccines, drugs, and other interventions.

Although many might consider such deliberate infections a dangerous form of playing with fire, focusing on the relapsing nature of Plasmodium vivax, this research has the potential to fill significant existing gaps in understanding and effectiveness of malaria treatment, the authors believe.

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