Background: Dengue fever is the most rapidly spreading mosquito-borne viral disease. Four main characteristic manifestations of dengue illness are (i) continuous high fever lasting 2-7 days; (ii) haemorrhagic tendency as shown by a positive tourniquet test, petechiae or epistaxis; (iii) thrombocytopoenia (platelet count <100×109/l); and (iv) evidence of plasma leakage manifested by haemoconcentration (an increase in haematocrit 20% above average for age, sex and population), pleural effusion and ascites, etc. Recently, novel platelet indices such as MPV, PDW, and P-LCR have been investigated as prospective platelet activation markers .Platelet volume, a marker of platelet function and activity is measured as mean platelet volume (MPV) by hematology analyzer. Method:The study was done with the aim to assess whether mean platelet volume has any diagnostic importance in the initial evaluation of dengue fever . 45 adult patients were diagnosed with Dengue NS1 antigen positivity and underwent routine complete blood counts on automated hematology analyser HORIBA Pentra ES60.Result: A total of 76 cases ranging from 6 months to 50 years of age were reported as antigenically positive for dengue indicating acute infection, out of which 45 were adults ranging from 12 to 50 years of age. 34 were male and 11 were female. Infants and children below 12 years of age were not included in this study. 55 controls were studied which included 31 males and 24 females. The mean platelet volume was found to be significantly higher in dengue cases when compared to controls. MPV was also noted to be significantly higher in patients with platelet count below the normal biological reference range of 1.5 lakhs ,when compared to dengue patients with normal platelet counts. Conclusion:To conclude, high MPV indicates platelet activation and may be used as an initial marker to suspect dengue fever in a case of thrombocytopenia.

BACKGROUND: Acute Febrile illness remains the leading cause of hospitalisation among adults and children in urban and rural regions of Southeast Asia(1). The Infectious diseases like dengue,enteric fever, leptospirosis, and scrub typhus are the common causes of Acute Febrile Illness. symptoms of such tropical diseases overlaps during the initial period of infection.CRP, an acute phase reactant, is gaining focus recently in delineating bacterial from viral infections. OBJECTIVE:To emphasize the usefulness of CRP in delineating bacterial from viral infections,in cases of acute febrile illness. METHODOLOGY:An observational study is conducted in a diagnostic lab of an NGO,Helping Hand Foundation,in Hyderabad.A total of 76 Patients were included in the study.The samples were received at the lab for analysing fever prole,during a period of 2 months i.e of September2021 to October2021. RESULTS:Out of 76 patients included in the study,21(28%) patients were diagnosed as having typhoid.15 (20%) were diagnosed with positive dengue serology and remaining 40 (52%) patients were included as having Acute Undifferentiated fever(AUF) with undetermined etiology and needs further evaluation. The p value for CRP levels,was calculated between the groups with signicant widal titres and positive dengue serology,which came as (p=0.0024)(C.I 95%),which is considered statistically signicant by conventional criteria. CONCLUSION:CRP levels are signicantly elevated in enteric fever cases when compared to the patients with positive dengue serology.Thus CRP can be a useful tool along with other blood investigations in differentiating bacterial and viral causes of Acute febrile illness.