Utility of High Fluorescent Cell Parameter on Automated Hematology Analyzer in Screening for Dengue Infection and Predicting Platelet Recovery: Objective and Cost-Effective Solution

Background and objective Dengue is a common febrile illness in tropical countries; serological detection of non-structural protein-1 (NS1) antigen or IgM is the gold standard for diagnosis. Thrombocytopenia, leukopenia, eosinopenia, and hem concentration are common hematological manifestations in dengue, and activated lymphocytes are seen in these patients. We intend to analyze the utility of a parameter called a high fluorescent cell (HFC) on Mindray BC-6000 for suspecting dengue infection in patients with febrile illness. Thrombocytopenia, when present, is taken as a warning sign and creates serious concerns for the treating physician. We studied HFC as a cost-effective tool to predict platelet recovery. Methods This is a facility-based single-gate cross-sectional comparative diagnostic accuracy study. Patients presenting with febrile illness and undergoing dengue serology testing and complete blood count (CBC) test with HFC enumeration on the same day were analyzed. Dengue-positive patients with thrombocytopenia were serially monitored for both platelet count and HFC, along with other platelet parameters. Results A total of 515 febrile patients were included. The median age of the patients was 18 (11-31) years, and 281 (54.56%) patients were males. Overall, the lab positivity rate for dengue was 33% (170 patients out of 515). The HFC in dengue-positive patients ranged from 0 to 20.1%. The sensitivity and specificity of absolute HFC count at a cut-off of 0.02 were 74% and 32%, respectively; similarly, the sensitivity and specificity of HFC percentage at a cut-off of 0.2 were 92% and 25%, respectively. Eighty-nine (out of 170) dengue-positive patients had thrombocytopenia. In 15 cases, multiple serial HFC and platelet counts were available. The falling trend in HFC was followed by platelet recovery within 24 hours in 13 (86.6%) patients. Conclusion HFC serves as a sensitive but not specific marker for dengue infection in cases with febrile illness. The role of HFC in predicting platelet recovery in dengue cases should be further explored.