Pseudobasophilia as a Screening Tool in Dengue: A Single Center Study.

 Proper serological testing for the definite diagnosis of dengue is costly and may not be easily available in a resource-limited setting. Hematological parameters can help in the early identification of dengue cases. This study aims to evaluate the occurrence and utility of pseudobasophilia in identifying dengue-affected patients.  This retrospective cross-sectional study included 1,304 dengue cases confirmed by serology and 1,044 dengue serology negative acute febrile illness cases as controls. Complete blood count (CBC) values of the first EDTA (ethylenediamine tetraacetic acid) blood sample from automated hematology analyzers were reviewed. The hematological parameters in the dengue and control groups were compared and the variation of these parameters with the day of fever was also analyzed.  Mann-Whitney's test, Kruskal-Wallis test, and Fisher's exact test were used for statistical analysis. A -value < 0.05 was considered statistically significant for all tests.  There was a statistically significant variation between dengue cases and controls for hematocrit, platelet count, mean platelet volume, total white blood cell count, and absolute basophil count. The dengue group had a higher hematocrit from day 2 to day 10, platelet count ≤ 100,000/µL from day 4 to day 9, higher mean platelet volume from day 2 to day 7, leucopenia from day 3 to day 5, and higher absolute basophil count from day 2 to day 10. Interestingly, pseudobasophilia was seen in 533 (40.87%) of dengue cases and only 3 (0.28%) of the controls. Pseudobasophilia was also observed to have an increasing trend to the day of fever.  Pseudobasophilia along with other CBC parameters is useful and cost effective for the early identification of dengue. This can prompt early investigations and supportive treatment leading to improved clinical outcomes.