Neutrophil–Lymphocyte Ratio as a Differential Diagnostic Biomarker in Dengue Fever and Enteric Fever: A Comparative Analysis

Abstract

Background: In tropical and subtropical areas, enteric fever and dengue fever are frequently responsible for an acute febrile illness and the clinical picture is sometimes similar, making early diagnosis difficult. Neutrophil-to-lymphocyte ratio (NLR) has been identified as a simple, cheap and readily available biomarker of systemic inflammation based on a complete blood count (CBC). This study was undertaken to assess the role of NLR for the diagnosis of enteric fever and dengue fever.
Materials and Methods: A prospective, hospital-based comparative observational study was done in the Department of General Medicine of a tertiary care teaching hospital for one year. One hundred consecutive patients with laboratory-confirmed acute febrile illness, 50 with enteric fever and 50 with dengue fever were enrolled. Demographic, clinical and laboratory parameters were obtained at admission. The independent Student's t-test was used to compare the different hematological parameters, inflammatory markers, and neutrophil-to-lymphocyte ratio between the two groups, and p < 0.05 was considered statistically significant.
Results: The most affected age group was young adults aged 21-30 years (46.0%) and males were 60.0% of the study population. Patients with enteric fever demonstrated significantly higher neutrophil counts (72.84 ± 8.16% vs. 56.48 ± 9.37%; p < 0.001), lower lymphocyte counts (18.26 ± 5.48% vs. 31.92 ± 7.24%; p < 0.001), and a markedly elevated neutrophil-to-lymphocyte ratio (4.32 ± 1.28 vs. 1.83 ± 0.69; p < 0.001) compared with patients with dengue fever. Dengue fever had significantly lower platelet counts (81.46 ± 31.74 × 10⁹/L) compared to enteric fever (164.72 ± 46.85 × 10⁹/L) and there was significant difference between two groups in C-reactive protein and erythrocyte sedimentation rate which were more elevated in enteric fever (p < 0.001). There was no statistically significant difference in T-LC among groups (p = 0.173).
Conclusion: Neutrophil to Lymphocyte ratio is easily available, inexpensive, simple and is a good useful marker to differentiate enteric fever from dengue fever in patients presenting with acute febrile illness. A significantly elevated NLR, in addition to elevated inflammatory markers and relatively well-preserved platelet counts, supports its potential as a complementary laboratory test for prompt clinical evaluation, especially in low-resource health care environments. Higher and larger multicenter studies are desirable to confirm the best diagnostic cut-off and to confirm the routine clinical use of NLR.