Nine year trends of dengue virus infection in Mumbai, Western India

Abstract

INTRODUCTION:Dengue virus (DENV) causes a wide range of diseases in humans, from acute febrile illness Dengue fever (DF) to life-threatening Dengue hemorrhagic fever (DHF) or Dengue shock syndrome (DSS). Factors believed to be responsible for spread of Dengue virus infection include explosive population growth, unplanned urban overpopulation with inadequate public health systems, poor standing water and vector control, climate changes and increased international recreational, business, military travel to endemic areas. All of these factors must be addressed to control the spread of Dengue and other mosquito-borne infections. The detection of Dengue virus RNA by reverse transcriptase PCR (RT-PCR) in human serum or plasma samples is highly indicative of acute Dengue fever. Moreover, the method is able to identify the Dengue virus serotype by demonstrating defined sequence homologies in the viral genomic RNA.METHODS AND RESULTS:During the nine year period of this study analysis, 6767 strongly suspected cases were tested by RT-PCR. 1685 (24.9%) were Dengue PCR positive and confirmed as Dengue cases. Observations on the seasonality were based on the nine year's data as the intensity of sampling was at its maximum during monsoon season. Dengue typing was done on 100 positive samples after storage of Dengue RNA at – 80°C. Dengue serotypes were detected in 69 samples of which Dengue 2 was most predominant. 576 samples were processed for NS1 antigen and PCR simultaneously. 19/576 were positive (3.3 %) for NS1 as well as by PCR. 23/576 samples were negative for NS1 antigen, but were positive by RT-PCR. The remaining 534 samples which were negative for NS1 antigen were also negative by Dengue RT-PCR.CONCLUSION:In this study we sought to standardize rapid, sensitive, and specific fluorogenic probe-based RT-PCR assay to screen and serotype a representative range of Dengue viruses that are found in and around Mumbai. Qualitative Dengue virus TaqMan assays could have tremendous utility for the epidemiological investigation of Dengue illness and especially for the study of the viremic response with candidate live-attenuated dengue virus vaccines.

Estimation of prevalence of dengue viral infection among clinically suspected patients attending a tertiary care centre in Uttar Pradesh, India

“…7,12 Dengue affects both the sexes of all age groups. In the present study males were more affected than females (6.16:1) and these results were consistent with the recently done studies done by Rao et al, Swain et al, Murhekar et al, Shastri et al [6][7][8]17 This may be explained by the difference in the nature of occupation, travel exposure and health seeking behaviour. More males may be reporting to the hospital for illness, as compared to females.…”

“…Most of the samples 161 (82.14%) were received during monsoon and post monsoon period June-November) with high positivity 27 (62.79%) for Dengue during post monsoon period October-November). Similar results were found in studies done by Gupta et al, Jain et al, Shastri et al [15][16][17] This seasonality trend may be due to favorable environmental factors when infected vector mosquitoes are abundant due to presence of ample stagnant water sources for mosquito breeding following heavy rainfall, high humidity lengthens their lifespan and increased temperatures shorten the virus extrinsic incubation period. 7,12 Dengue affects both the sexes of all age groups.…”

“…18 These findings indicate the importance of working place and travel on dengue prevalence, which needs further exploration. [5][6][7][8]15,17 Whereas, in studies done by Jain et al, Dar et al children of age group less than 15 were affected more. 16,18 This study had certain limitations also.…”

Severe Dengue Epidemic, Sri Lanka, 2017

“…an aging but active elderly population (31)(32)(33). On the other hand, in countries such as India, Vietnam, and Brazil, dengue incidence is increasing in a higher proportion of persons in younger age groups (27,34,35). In many countries, serotype switches of circulating dengue viruses have been associated with severe epidemics when the population is exposed to a new serotype (36,37).…”

“…The southwest monsoon brings in heavy rainfall midyear (May-September) to Western, Sabaragamuwa, Southern, and Central provinces, and the northeast monsoon brings a relatively heavy rainfall during December-February for the Northern, North Central, Uva, and Eastern provinces. The midyear peak in dengue incidence in 2017 was exceptionally high in all provinces affected by the southwest monsoon (weeks [25][26][27][28][29][30][31][32][33][34][35].…”