Molecular detection of dengue virus serotypes prevalent in central Kerala and its correlation with disease severity

Abstract

Dengue is the most important mosquito-borne viral disease in the world. In 2017, a concerning increase in dengue cases with high mortality was seen in India with Kerala topping the list. Changing pattern of circulating dengue virus serotype and co infection with multiple serotypes contribute to the increasing trend in severity and increased mortality of dengue fever. The present study focused to find the dengue serotypes prevalent in central Kerala and prevalence of co infection with multiple serotypes here with an attempt to correlate these with clinical severity of dengue: This descriptive study was done in the Microbiology department of Jubilee Mission Medical College, Thrissur for a period of 18 months. Blood samples of clinically suspected dengue fever cases which were positive for NS1 antigen and having fever not more than 5 days were subjected to molecular methods to detect dengue virus RNA followed by multiplex RTPCR to find its serotype. Demographic features, clinical details and lab parameters were also collected from each patient. A total of 108 samples positive for Dengue NS1 antigen were subjected to RT-PCR. Among them 61(56.5%) were positive by RT-PCR. All the 4 Dengue serotypes were found with DENV-2 with 30 cases (49.2%) being the predominant serotype followed by DENV-1 with 20 cases (32.8%), DENV-3 with 12 cases (19.6%) and DENV-4 with 2 cases (3.27%). Three cases (4.9%) of co infection with DENV-1,2, DENV-1, 4 and DENV-2,3 were also found. Two among the 108 patients (1.85%) died in the present study. Significant correlation between severity of dengue infection and serotypes could not be found due to very few severe cases encountered during the study. : The dengue serotypes predominant in central Kerala is DENV-2. The prevalence of co infection with multiple serotypes is 4.9% which proves that this area has become hyper endemic to the disease, which increases the risk of emergence of more severe cases.