Fast, inexpensive test for malaria drills down to specifics

In ongoing efforts to eradicate malaria, an ultrasensitive test that offers rapid, species-specific diagnostic capabilities has been developed by a research collaboration led by James Collins, a core faculty member at Harvard’s Wyss Institute for Biologically Inspired Engineering.

To achieve the goal set by the World Health Organization’s (WHO) Global Malaria Control Programme, all local transmission of malaria parasites in defined geographic areas must be eliminated. Developing tests that are useful in the low-resource settings of many areas with endemic malaria is key.

Currently, the presence of the four major malaria-causing Plasmodium species P. falciparum, P. vivax, P. ovale, and P. malariae is determined by microscopic analysis of blood samples in which parasites can be detected in red blood cells, or with so-called rapid diagnostic tests for specific Plasmodium proteins (antigens).

“Unfortunately, available rapid diagnostic approaches cannot distinguish all four Plasmodium species from one other, which can be important to initiate the definitive course of treatment,” said Nira Pollock, associate medical director of Boston Children’s Hospital’s Infectious Diseases Diagnostic Laboratory and associate professor of pathology and medicine at Harvard Medical School (HMS). “And, most importantly, they are ineffective for detecting low numbers of Plasmodium parasites in asymptomatic individuals.”

“These ‘asymptomatic carriers’ are silent reservoirs for ongoing transmission by malaria-spreading mosquitoes and extremely important for ongoing global efforts to eradicate malaria,” added Jeffrey Dvorin, associate professor of pediatrics at HMS and senior associate physician in infectious diseases at Boston Children’s Hospital.

The research team, assembled by clinical fellow Rose Lee and included Pollock and Dvorin, created a field-applicable, ultrasensitive diagnostic assay that specifically detects DNA sequences from all Plasmodium species in symptomatic and asymptomatic malaria. The new method combines an optimized 10-minute rapid sample preparation protocol with the CRISPR-based SHERLOCK system to enable highly specific and sensitive Plasmodium detection in another 60 minutes in simple reporter devices. It is published in PNAS.