Rapid POC Diagnostic Test Detects Asymptomatic Malaria Cases

Asymptomatic infections are a major driver of ongoing transmission because individuals who carry the disease without showing symptoms do not seek medical treatment, yet can still infect mosquitoes. Detecting these low-level, symptom-free infections quickly and outside a laboratory has long been a major barrier to elimination efforts. Now, researchers have developed a low-cost, point-of-care molecular diagnostic that can identify extremely low levels of malaria parasites from a finger-prick sample, enabling rapid detection of infections that would otherwise go unnoticed.

The test, called Dragonfly, was developed and validated by scientists from Imperial College London (London, UK) and collaborators. The Dragonfly process extracts high-purity nucleic acids from a capillary finger-prick sample in about 10 minutes, places the prepared sample into a detection panel inserted into a portable heater, and gives a visual readout after a 30-minute incubation (pink = negative, yellow = positive). The system is compact, battery-operable, can fit in a backpack, and is designed to be used outside traditional laboratory settings by users without extensive training.

Almost 700 blood samples were collected from communities in The Gambia and Burkina Faso to assess Dragonfly against gold-standard PCR, expert microscopy, and common rapid diagnostic tests. The study, published in Nature Communications, found the Dragonfly tool could detect over 95% of all malaria parasite infections, including 95% of infections with parasite counts too low for microscopy to see.

Because Dragonfly is sensitive, scalable, and field-deployable, it offers a route to community-based test-and-treat strategies that could reduce transmission by identifying asymptomatic carriers. The team is already exploring production and scale-up with local manufacturers and working with the Africa Centers for Disease Control and Prevention to root manufacturing in regional capacity. Future work will assess robustness in more remote community settings and evaluate the final manufactured cost for large-scale deployment.

“This is the first time that a diagnostic test for use outside of a laboratory setting has proven sensitive enough to detect low level malaria parasite infections in people who don’t have any symptoms,” said Professor Aubrey Cunnington, co-author on the study. "Until now, no test has been able to detect enough of these infected people to make this a viable proposition, but the Dragonfly test now makes this possible."

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Imperial College London