Key Points
- Conventional means of testing for malaria typically involves drawing blood, which is invasive. Alternative, less invasive techniques are being tested with more readily available biofluids.
- Volatile organic compounds were extracted from malaria-negative and -positive individuals to identify potential malaria infection signatures.
- Procedures were conducted using wearable silicone rubber (polydimethyl siloxane [PDMS]) sampling bands adhered to the surface of the epidermis.
- The method, based on thermal desorption-comprehensive two-dimensional gas chromatography-time-of-flight-mass spectrometry (TD-GC × GC-TOFMS), proved effective.
Researchers from the University of Pretoria in South Africa analyzed various volatile organic compounds (VOCs) for malaria markers using thermal desorption-comprehensive two-dimensional gas chromatography-time-of-flight-mass spectrometry (TD-GC × GC-TOFMS). Their procedures and findings were published in the Journal of Chromatography A (1).
Malara is a parasitic disease spread to humans through the bites of infected mosquitoes (2). Symptoms can include fever, nausea and vomiting, and fatigue. The World Health Organization (WHO) estimates that there were 263 million cases of malaria in 2023, with 597000 estimated worldwide mortalities (3). Mosquitoes of the genus Anopheles are the vectors of the malaria-casting Plasmodium parasite; while there are more than 100 known species of this parasite, only four are known to infect humans: Plasmodium falciparum, P. vivax, P. malariae and P. ovale. While malaria symptoms typically begin within a few weeks after a bite, but some types of malaria parasites can lay dormant for at least a year.
Conventional malaria testing methods typically involves blood-draws, which are invasive. As such, researchers are looking into alternative and less invasive diagnostic procedures that use more readily available biofluids, such as exhaled breath.
In this study, volatile organic compounds (VOCs) were extracted from malaria-negative and -positive individuals, specifically from clinic attendees in the Vhembe district of Limpopo Province, South Africa. The samples were taken using wearable silicone rubber (polydimethyl siloxane [PDMS]) sampling bands adhered to the surface of the epidermis. The samplers were then analyzed by thermal desorption-comprehensive two-dimensional gas chromatography-time-of-flight-mass spectrometry (TD-GC × GC-TOFMS). Individual cutaneous VOCs and semi-VOCs (SVOCs) profiles were constructed from the chromatographic profiles to identify potential Plasmodium infection signatures. Targeted analyses were performed for compounds previously reported to be associated with Plasmodium infection; this includes heptanal, (E)-2-octenal, 2-octanone, octanal, nonanal and (E)-2-decenal.
The linearity (R2) range was 0.93–0.99 for a matrix matched (simulated cutaneous sampling) calibration range of 2.5–60 ng. Limits of detection (LOD) ranged from 0.4 pg (2-octanone) to 6.3 pg ((E)-2-octenal), whilst limits of quantification (LOQ) ranged from 1.4 pg to 21.1 pg. The mean percentage recoveries (n = 2) ranged from 77.8% ((E)-2-decenal) to 118.9% (2-octanone). The percentage relative standard deviations (%RSDs; n = 2) ranged from < 1% for 2-octanone, octanal and nonanal to 27.1% for (E)-2-octenal.
According to the researchers, the previously investigated compounds were found to be non-specific for Plasmodium infection when compared to control subjects with comorbidities. A previously unreported compound, (E)-2-octen-1-ol, correlated with malaria-positive participants, though it was also found in two malaria-negative participants. This could suggest latent cases of malaria, which could merit a follow-up study involving a larger participant cohort.
Overall, the authors emphasized more cautious interpretation of results from cohorts if there is risk of controls having comorbidities. Non-specificity can always be a factor, and it should always be considered. Further, potential markers of interest should not be assumed to be disease-specific pending further investigation.
References
(1) Pretorious, D. T.; Rohweer, E. R.; Naudé, Y. Cutaneous Volatile and Semi-Volatile Organic Compounds as Markers of Malaria-Infection by Wearable Samplers and Two-Dimensional Gas Chromatography—Time-of-Flight-Mass Spectrometry. J. Chromatogr. Open 2025, 8, 100233. DOI: 10.1016/j.jcoa.2025.100233
(2) Malaria. Mayo Clinic 2023. https://www.mayoclinic.org/diseases-conditions/malaria/symptoms-causes/syc-20351184 (accessed 2025-6-26)
(3) World Malaria Report 2024: Addressing Inequity in the Global Malaria Response. World Health Organization 2024. https://www.who.int/teams/global-malaria-programme/reports/world-malaria-report-2024 (accessed 2025-6-26)
