WASHINGTON — Researchers have developed a new microscopy method that uses a magnetic field and polarized light to provide quantitative measurements that could enable faster and more objective detection of malaria in blood.
Malaria, caused by Plasmodium parasites transmitted by mosquitoes, infects over 200 million people around the world each year, causing more than 600,000 deaths. Faster, more objective detection methods are needed to improve diagnosis, guide treatment and enable large-scale screening, especially in low-resource settings.
"Our method doesn't require expert interpretation and works without needing to stain or chemically treat the sample, making testing more accessible and easier to perform consistently," said research Dickson Mwenda Kinyua from Kirinyaga University in Kenya, who performed this work in collaboration with Pietro Cicuta's research team at the University of Cambridge . "This could lead to earlier detection, better treatment decisions and ultimately better health outcomes."
In the Optica Publishing Group journal Biomedical Optics Express , the researchers describe the new detection technique that leverages the unique properties of hemozoin, a crystal that malaria parasites naturally produce inside red blood cells. Laboratory tests performed on malaria-infected samples showed that the method can detect and quantify malaria-related signals.
"Our method not only makes it possible to see malaria but also allows more precise measurements and the potential to map its location in the sample," said Kinyua. "This quantitative information could be very useful in laboratories and hospitals where it could provide faster, more consistent and sensitive diagnosis. It could also make it possible to develop automated approaches for diagnosis."
Magneto-optical malaria detection
Although microscopy is already widely used for malaria detection, it typically requires time-consuming sample preparation, and the results are not always clear.
To make microscopy more objective and easier to use, the researchers used the hemozoin crystals produced by the malaria parasite when it digests hemoglobin inside red blood cells. These crystals are magnetically anisotropic and exhibit optical dichroism, meaning they tend to align in a magnetic field and interact with light differently depending on their orientation.
"Earlier magneto-optical approaches typically provided bulk information about the sample, which can hide important details," said Kinyua. "With our method, we can detect not only how strong the signal is, but also exactly where it is coming from within the sample. This is all done using relatively simple and accessible components."
The new method involves placing a blood sample under a polarizing microscope and then applying a controlled magnetic field. The magnetic field causes any hemozoin crystals present to rotate and align in a preferred direction, changing how they interact with polarized light and producing measurable shifts in image intensity and contrast.
The researchers then apply ratiometric intensity analysis — comparing image intensity before and after magnetic alignment — along with threshold-based segmentation to measure the magneto-optical signal. This makes it possible to link the signal strength to hemozoin concentration, providing quantitative information.
Testing on blood samples
The researchers tested the approach by imaging blood samples with and without malaria under a polarizing microscope while applying a magnetic field. The results showed a consistent signal that linearly correlated with the amount of hemozoin present, demonstrating that the method can reliably detect and quantify malaria-related signals.
