Introduction: Dengue fever is the most common Arboviral disease in the world. The four serotypes of dengue virus, 1,2,3 and 4 form an antigenic subgroup of flavivirus. The clinical manifestations of dengue fever range from in apparent to lethal. Various  hematological parameters and reactive lymphocytes (Virocytes)/Plasmacyatoid lymphocytes in peripheral smear can help us in the diagnosis of dengue fever.

Aim: The aim of the study is to emphasize on the utility of hematological parameters  and peripheral smear reactive lymphocytes (virocytes)/plasmacyatoid lymphocytes in the diagnosis of dengue fever.

Materials and Methods: A study was carried on a series of patients who attended various health care centres in and around Kurnool for a period of one month. Patients presented with complaints of fever, headache, rash and body pains. Then these patients were tested for dengue, then those positive cases hematological parameters and peripheral smear were analysed.

Results: Out of 100 dengue positive cases, 40 cases showed increased hematocrit, 60  cases had leucopenia, 100 cases had thrombocytopenia and 60 cases had relative lymphocytosis. On peripheral smear examination 100 cases showed reactive lymphocytes/ plasmacyatoid lymphocytes.

Conclusion: Presence of raised hematocrit, leucopenia, relative lymphocytosis, thrombocytopenia and reactive lymphocytes in peripheral smear helps in the diagnosis of dengue fever. 

Keywords: Dengue Fever; Hematological Parameters; Peripheral Smear; Reactive Lymphocyte; Thrombocytopenia.