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doi:10.1038/nindia.2016.160 Published online 2 December 2016

Dengue or chikungunya: Solving doctors’ dilemma

K. S. Jayaraman

Scientists at the International Centre for Genetic Engineering and Biotechnology (ICGEB) in New Delhi have identified specific molecules in patients of dengue and chikungunya that can be used to develop biomarkers to differentiate these confusingly similar infections1.

Dengue and Chikungunya are spread by the same mosquito species (Aedes Aegypti) and show similar symptoms. This makes diagnosis a real challenge for doctors. Treatment gets further complicated when both infections are simultaneously present in the patient.

To help doctors make a precise diagnosis, Sujatha Sunil, who heads the vector borne diseases group at ICGEB, and her colleagues set out to identify the biochemical markers specific to dengue and chikungunya by analysing the ‘metabolome’ of the patient's sera. Metabolome is the complete set of small-molecule chemicals found within a biological sample.

Although these two infections together affect about 40 million people globally, very few studies have tried to understand the differentiating features between them, Sujatha told Nature India.

Using metabolomics, or the systematic study of the unique chemical fingerprints (metabolites) created during a disease condition, they tried to identify molecules that could be used to develop the biomarkers.

They used nuclear magnetic resonance spectroscopy to profile the metabolites of sera samples from 11 patients with dengue, 15 with chikungunya and 12 co-infected. These profiles were then compared with the metabolome of 15 healthy controls without any infection.

"We identified unique metabolite signatures for chikungunya mono-infections and co-infections with dengue,” she said.

For instance, 2-ketobuyric acid, one of the metabolites, was totally absent in chikungunya patients while the metabolite sorbitol was absent in the dengue group. The researchers report that many metabolites in the serum are "significantly differentially regulated" during chikungunya infection as well as during a co-infection with dengue. "The affected pathways in our study correlate well with the clinical manifestation like fever, inflammation, energy deprivation and joint pain during the infections."

Analysis of the sera metabolome revealed that distinct metabolites were deregulated in distinct disease conditions, the authors report. "They could be used as biomarkers specific to that condition", says co-author Neel Sarovar Bhavesh, leader of the Transcriptional Regulation Group at ICGEB.

Further validation of these metabolites over a larger patient population may help identify distinct biomolecules that could be exploited for differential diagnosis, the researchers say.


References

1. Shrinet, J. et al. Serum metabolomics analysis of patients with chikungunya and dengue mono/co-infections reveals distinct metabolite signatures in the three disease conditions. Sci. Rep. 6, 36833 (2016) doi: 10.1038/srep36833