Researchers have developed a saliva-based test to rapidly identify children who harbor reservoirs of the malaria parasite, according to study results published in Science Translational Medicine
“There is an unmet need for sensitive [point-of-need (PON)] diagnostic tests that can identify subclinical carriage of Plasmodium asexual parasites and gametocytes in human populations in clinical, port, school or home settings,” the researchers wrote. “Such a need is more pronounced in the context of malaria elimination and eradication, especially because countries entering the elimination phase will be faced with the challenge of detecting low-density parasite carriage in the midst of reductions in infection prevalence.”
The researchers noted that no PON rapid diagnostic tests (RDTs) for gametocyte detection currently exist.
They examined saliva samples from 12 children in Mfou, Cameroon, with subclinical parasitic infection and discovered 35 parasitic markers, from which they selected a single candidate to use in a PON RDT. They wrote that PF3D7_1218800 was the most abundant protein; they then selected PSSP17 as a candidate gametocyte marker and developed a liquid chromatography-multiple reaction monitoring mass spectrometry workflow to detect PSSP17 in saliva in children with subclinical infection to estimate the prevalence of marker carriage.
Anopheles gambiae is the primary mosquito vector for malaria
The researchers conducted a cross-sectional, multi-omics study of 364 children from Cameron and Zambia with subclinical infection and created a prototype saliva-based PON lateral flow immunoassay test for Plasmodium falciparum gametocyte carriers. They reported that the test was able to identify submicroscopic carriage in clinical and nonclinical settings and was compatible with archived saliva samples.
“We propose that pairing such a diagnostic with ‘stamp out’ interventions such as a malaria transmission-blocking vaccine would permit a more targeted immunization strategy that may lower the cost of such campaigns,” the researchers concluded. – by Bruce Thiel
Disclosures: Tao reports being an inventor on a patent/patent application (PCT/US2016/037968) held/submitted by Johns Hopkins University that covers the saliva-based malaria test in the study. Please see the study for the other authors’ relevant financial disclosures.