A comparative study of clinical symptoms, demographic characteristics and laboratory parameters among primary and secondary dengue cases in a tertiary care hospital in Kolkata

Dengue, an arthropod borne viral disease which is transmitted to humans through the bite of infected Aedes mosquitoes, can result in a range of clinical presentations from mild febrile illness like dengue fever (DF) to severe presentations like dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) which can turn fatal.While majority of primary dengue cases are asymptomatic/ mild symptomatic, secondary dengue infected cases usually have more complications and require critical care support.To find out proportion of Dengue IgG among NS1 reactive cases, study their clinical-demographic profiles and to find out the prevalent dengue serotypes.Blood collected from patients suffering from acute febrile illness less than 5 days and more than 5 days duration were tested for Dengue NS1and Dengue IgM respectively. Samples reactive for Dengue NS1 were further tested for dengue IgG by ELISA and dengue serotyping by RT-PCR. Results obtained were analysed and interpreted.Out of 2286 blood samples suspected for Dengue during the study period (March 2021 to February 2022), only 134 samples were NS1 reactive and amongst them, 21 (16%) had early detection of IgG antibodies while the rest 113(84%) cases were primary dengue infection. The predominant serotype was DENV-3.It is evident that patients who suffer from Secondary Dengue infections require more supervision and critical care support. This highlights the importance of Dengue IgG detection in the early phase of the disease in order to predict the complications of dengue which can save many more lives. Nevertheless, Primary dengue infections can also be severe, hence should be monitored closely under supervision. Molecular surveillance may help to predict large scale outbreaks of dengue if regional shifts in the predominantly circulating serotypes are detected during the early phase of the dengue season.