With the pandemic still in full force, even the mildest fever can be cause for alarm. How do you know if your fever is just the sign of a cold—or worse, COVID-19? As fevers are our body’s standard response to any type of infection, it’s nearly impossible to know what’s causing it without a test.
In Saudi Arabia, where millions of people travel in and out for the annual Hajj pilgrimage, this question is especially relevant. Given the mass movement of people—and even livestock for food—the country is a hotspot for the transmission of infectious tropical diseases such as malaria, dengue and more.
However, these diseases share similar symptoms like fever, making them hard to diagnose. While laboratory tests such as polymerase chain reaction (PCR) and microbial culture methods can tell the different febrile diseases apart, they are either too expensive or too slow. Now, researchers have identified distinct biomarkers that may lead to speedier and more accurate diagnosis of the different febrile illnesses in Saudi Arabia.
“There is a lack of research focus on neglected tropical diseases, especially in the Arabian region,” said corresponding author Lisa Ng, Executive Director of A*STAR’s Biomedical Research Council (BMRC) and Infectious Diseases Labs (ID Labs). “To our knowledge, this is the first extensive characterization and identification of disease-specific cytokines in a myriad of febrile illnesses in Saudi Arabia.”
Biomolecules called cytokines are triggered in response to infections by pathogens, making them a good diagnostic tool. In their study, Ng and her colleagues analyzed blood samples from over 2,000 febrile patients from King Fahad Central Hospital in Jazan, Saudi Arabia, to identify the cytokines that could distinguish between dengue, malaria, streptococcal and meningococcal infections.
For instance, although dengue infections induced high levels of cytokines like RANTES—which attract immune cells to inflammation sites—decreased levels of these same cytokines occurred during malaria and were even lower in bacterial infections.
“The cytokines identified in this cohort can be used as predictive biomarkers to confirm or provide preliminary diagnosis, especially for febrile illnesses with overlapping clinical symptoms,” said Ng, adding that tests developed using these immune signatures will provide faster results than culture diagnostic methods with long turnaround times.
However, more work is required before such diagnostic tests can be put into practice. “To further evaluate the robustness of the immune signature, there needs to be more investigations into its implementation in hospital diagnosis practices as well as validation with various patient cohorts,” Ng concluded.
The A*STAR-affiliated researchers contributing to this research are from the Singapore Immunology Network (SIgN) and Infectious Diseases Labs (ID Labs).