Evaluation of thrombocytopenia in dengue infection along with seasonal variation

Introduction: Dengue fever is one of the most prevalent and fastest spreading mosquito borne arboviral infection, occurring in tropical and subtropical regions. They are single stranded RNA viruses and transmitted by Aedes mosquitoes. There are four serotypes of dengue virus DENV 1, DENV2, DENV3, DENV 4. Following an infection lifelong immunity develops against the respective serotype. The clinical spectrum of dengue infection varies from undifferentiated fever, Classical Dengue fever, Dengue hemorrhagic fever, Dengue shock syndrome, Expanded dengue syndrome. Continuous surveillance of dengue fever is important for the proper and timely institution of vector control measures. Aim: The aim of present study was to evaluate the thrombocytopenia with prevalence of dengue infection along with seasonal variation. Materials and methods: The present study was a retrospective study conducted in the Department of Hematology, at Chalmeda Anand Rao Hospital, Karimnagar during the period from 2015 June to 2016 May. Blood samples were collected from 4047 patients presented with acute febrile illness clinically consistent with Dengue infection. Serological confirmation of dengue infection was done using “Rapid Visual test kit” for detection of NS1 antigen and differential detection of IgM and IgG. Platelet count was done on “Automatic cell counter XN1000” which was correlated with manual platelet count in all the serologically positive cases. Results: Out of 4047 suspected cases, 1505 cases were confirmed as serologically positive for dengue infection. Out of 1505cases, 742 samples were positive for only NS1, 70 were positive for only IgM, 361 were positive for only IgG, remaining 332 were positive for more than one serological markers (NS1, IgM, IgG). A majority, 655 (43.52%) of the dengue cases were noted in the age group of 15-30 years, followed by less than 15 years of age. Among the dengue cases, 61.8% were males and 38.2% were females. A significantly higher number of serologically positive cases 1342 (89.2%) were noted in the post monsoon period. Conclusion: Incidence of dengue infection was higher in monsoon and post monsoon period. Thrombocytopenia provide high suspicion of dengue infection, which could be life threatening. Platelet count is an important predictive and recovery parameter of dengue infection.