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Saliva-Based Test Detects Malaria Prior to Symptom Onset

JAN 17, 2019 | MICHAELA FLEMING
Clinicians typically use blood samples to test for malaria, but these tests often miss subclinical parasite infections that cause the disease, leading to incorrect results. But now, investigators have developed a rapid lateral flow assay that can detect the subclinical presence of a protein biomarker for malaria in saliva.

A research article published in Science Translational Medicine indicates that the investigative team conducted a “cross-sectional, multi-omics” study of saliva from 364 children with subclinical malaria infections in Cameroon and Zambia and produced a prototype point-of-need rapid diagnostic test that detects Plasmodium falciparum gametocyte carriers.

According to World Health Organization (WHO), Plasmodium falciparum accounts for approximately 99% of malaria cases in Africa, 62.8% of cases in South-East Asia, 69% of cases in Eastern Mediterranean, and 71.9% of cases in the Western Pacific.

The investigators report that the test is able to identify “submicroscopic carriage” outside of clinical settings and can even analyze archived saliva samples.

The investigative team comprised 24 investigators and the proof-of-concept study was conducted in more than 300 children in the African nations of Cameroon, Zambia, and Sierra Leone.

Early detection of malaria prior to the onset of symptoms is critical because asymptomatic individuals who carry the parasite are the reservoirs that lead to further transmission of the disease.

According to the WHO, adults living in areas where malaria is endemic can develop partial immunity; therefore, children under the age of 5 are at a higher risk for malaria infection, illness, and death.

“We are trying to understand malaria transmission by working with people who are not yet sick because those are the people we miss in the clinic,” Rhoel Dinglasan, associate professor of infectious diseases in the College of Veterinary Medicine at the University of Florida Emerging Pathogens Institute and study author, said in a statement. “Malaria is like a big iceberg that we’ve always chipped away at on top, above the water line. But it’s the bottom of the iceberg, this reservoir for transmission, that we don’t understand because it’s a population that, until now, we could not see.”

The saliva test is a more efficient option because it is non-invasive, reducing the anxiety accompanied with blood drawing, and does not require trained clinicians. Additionally, because the test consists of the submission of a saliva sample, it can be administered outside of clinical settings. Early detection can lead to early treatment and the prevention of disease and further transmission of malaria.

Additionally, the test can detect essential proteins that the parasite needs for survival, which should eliminate any issues called by mutation of the virus and keep the test long-term effective.

“The ultimate goal really is to be able to develop a diagnostic that’s based on saliva that will allow us to differentially diagnose an individual who presents in a clinic [or school] to identify really quickly do they have malaria?” Dr. Dinglasan stated further.

The development of the test was led by Dr. Dinglasan, who began working on the project while a faculty member at Johns Hopkins University in 2014. The project received funding from the Bill and Melinda Gates Foundation.
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