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Grant supports development of novel noninvasive test for malaria

July 27, 2023
by Jessica M. Scully

A research team co-led by Yale School of Public Health professor Dr. Sunil Parikh, MD, MPH, has received $500,000 in funding from the Bill & Melinda Gates Foundation to continue the development of an innovative noninvasive test for malaria using lasers and ultrasound.

The grant will allow researchers to build two improved prototypes of their cytophone testing platform and to do extensive field testing in the West African nation of Burkina Faso, where malaria is endemic, said Parikh, an associate professor of epidemiology (microbial diseases) at YSPH and of infectious diseases at the Yale School of Medicine. Parikh is a co-principal investigator on the project.

“The goal is to get at both the sensitivity and the specificity of this device,” Parikh said. “I think this grant is going to help us move the research to the next phase.”

Malaria is an enormous health problem globally. In 2021 (the most recent year for which data is available), nearly half of the world’s population lived in an area where malaria is endemic, according to the World Health Organization. There were an estimated 247 million malaria cases that year — an increase of two million compared with 2020 — and 619,000 deaths, according to the WHO. Young children, pregnant women, and nonimmune travelers are the most vulnerable to severe infection.

A meeting sparks an idea

Parikh’s co-principal investigator is Professor Vladimir Zharov, director of the Arkansas Nanomedicine Center at the University of Arkansas for Medical Sciences (UAMS) and co-founder of CytoAstra, a UAMS spinoff company advancing cytophone research. CytoAstra is a sub-award recipient of the Gates Foundation grant. Zharov and Parikh met at a conference in Uganda in 2017. Zharov had been pioneering noninvasive technologies for medical applications and was presenting his work on detecting circulating melanoma cells noninvasively using what was then a large, nonportable early prototype of the cytophone platform housed at the University of Arkansas. Realizing the platform’s potential application for human malaria, Zharov teamed up with Parikh, whose research centers on malaria interventions in Africa, to develop a portable prototype that could detect malaria infection in people living in endemic settings.

For malaria, the cytophone technology uses lasers at specific wavelengths focused on superficial blood vessels. When the parasites that cause malaria infection enter red blood cells, they use the hemoglobin inside those cells to liberate amino acids. A byproduct of this process is the release of hemozoin, a compound containing iron. When hit by a laser, hemozoin absorbs more of the laser’s energy than hemoglobin, meaning cells infected with malaria parasites absorb more than noninfected cells. This absorbed energy is transformed into heat, and the heat expansion generates acoustic waves. The cytophone technology detects these waves using a small ultrasound transducer placed on the skin. After software analysis, peaks in the detected acoustic waves can identify malaria infection.

In a prior study published in Scientific Reports, Zharov and Parikh showed their device could identify infection in mice using a rodent species of malaria parasite and in blood using a human malaria parasite. The Zharov team then developed a portable version of the device, and the researchers jointly completed a human proof-of-concept study in malaria-infected adults in Cameroon with Professor Yap Boum, a long-standing collaborator of the Parikh lab who is currently executive director of the Pasteur Institute of Bangui. The results were promising and are under review for journal publication, Parikh said.

Parikh praised the multidisciplinary collaborative effort with Zharov and their Cameroonian colleagues in advancing the technology. Working together “opened doors that we would never have been able to open separately,” he said.

Fine-tuning the prototype

As successful as it was initially, there were still some unanswered questions with the pilot study. The first portable device was more complex to operate and needed upgrading for durability and precision. The researchers also wanted to expand their clinical work beyond adults clearly infected with malaria to study people with asymptomatic infections, including children.

The Gates Foundation grant allows the team to do both. In the initial stages of the grant, Zharov’s lab will use the funding to build two new, smaller more advanced prototypes of the device that are more durable and have improved ultrasound, laser, and software processing.

Parikh will then co-lead clinical studies to validate the technology, working with collaborators in Burkina Faso. The updated devices will be sent to the country to assess how well they perform in diagnosing malaria in adults both with and without malaria. School-aged children with symptomatic malaria will also be studied through coordination with an institute led by Jean Bosco Ouedraogo, an adjunct professor at YSPH.

The team’s goal is to fine-tune the device to make sure that it can acquire data with a clean signal and to understand what might cause a false positive or negative result, Parikh said.

A more sensitive test

The technology could eventually represent a big improvement in diagnosing, treating, and understanding malaria, he said.

Malaria is currently diagnosed by two methods. In light microscopy, long the standard for diagnosis, blood is smeared on a slide, stained, and studied under a microscope. But because this requires resources and expertise, it is being replaced in many areas by rapid antigen blood tests. These are designed to react to the presence of a specific antigen, or protein found on the surface of a pathogen, in a sample.

A problem with both methods is that they aren’t very sensitive. “You can have a very large parasite load with both microscopy and rapid diagnostic tests before you have a positive test,” Parikh said.

Because the cytophone platform can potentially scan a much larger volume of blood, it should be far more sensitive than current tests, Parikh said. The technology also could address an emerging problem with some antigen tests, he added.

In Africa, the most common antigen tests search for an antigen on Plasmodium falciparum, the locally dominant of the five species of protozoa that cause human malaria, and the most dangerous. But researchers are finding more and more samples of the parasite with deletions of that antigen. In some places, most of the parasites no longer express that antigen, Parikh said.

Since cytophone uses hemozoin, which all species of malaria parasites produce as part of their life cycle, as a marker, it would avoid this problem, Parikh said.

“We don’t think that there’s ever a situation where hemozoin wouldn’t be present over the life cycle of the parasite,” he said.

In addition to diagnosis problems, a challenge plaguing malaria treatment in the long term is that the parasites become resistant to medications. Since the technology focuses on hemozoin, it could be useful to researchers trying to develop and study new antimalarial drugs that target this pathway in humans, noninvasively, Parikh said. “I think that would be a really exciting avenue for this device.”

Submitted by Colin Poitras on July 27, 2023