Epidemic profile of common respiratory viruses in association SARS CoV-2 among SARI and ARI-two year study.

BACKGROUND: COVID-19/SARS CoV-2 continue to pose a threat to human health and placed millions of livelihoods at risk. Surveillance for the other circulating seasonal viruses during this pandemic is necessary to understand the manifestations of the CoV-2 pandemic and their incidence. METHODS: A detailed study survey was performed on subjects with acute respiratory infections (ARI) and severe acute respiratory infection (SARI) in the King Institute of Preventive Medicine and Research, Chennai from April 2020 to March 2022. A total of 1480 patients presenting with either SARI (41.8%) or ARI (58.1%) were screened for SARS CoV-2 and other respiratory viruses. The SARS CoV-2 real-time PCR was carried out using ICMR-approved kits and other respiratory viruses were detected using the commercially available real-time kit. RESULTS: Out of the 620 SARI patients, 198 (31.9%) were positive for SARS CoV-2 RNA. Out of the 860 ARI patients, 352 (40.9%) were positive for SARS CoV-2 RNA. Among the 550 patients positive for SARS CoV-2, 7 (1.2%) were positive coexistent with other respiratory viruses. Among the 930 patients with negative SARS CoV-2, 222 (23.8%) were positive for other common respiratory viruses (p = 0.001). Influenza viruses (36.9%) predominated followed by RSV (31.9%) and Parainfluenza virus (13.5%). CONCLUSION: This study suggests that viral coinfections are significantly higher among SARS CoV-2 negative individuals (23.8 vs. 1.2%). It is possibly due to viral interference and the competitive advantage of SARS CoV-2 in modulating the host immunity. Continuous surveillance is necessary for understanding the viral co-infection mechanisms.

Poliovirus nonpermissive CD155 knockout cells derived from RD cell line for handling poliovirus potentially infectious materials in virology laboratories.

Destruction of all poliovirus containing materials, safe and secure handling of retained polioviruses for vaccine production, and research will be obligatory to eliminate facility-associated risks. Polioviruses and poliovirus potentially infectious materials (PIM) including fecal or respiratory samples requiring containment have been defined in World Health Organization-Global Action Plan (GAP III) documents. Non-polio laboratories culturing viruses from PIM are most affected as cell cultures of human and monkey origin are also poliovirus permissive. CRISPR gene-editing technology was used to knockout the poliovirus receptor (PVR/CD155) gene in the rhabdomyosarcoma (RD) cell line. PVR knockout RD cell susceptibility was tested using known non-polio enterovirus (NPEV) types. A selected clone (RD-SJ40) was field evaluated for virus isolation from 626 stool samples of acute flaccid paralysis cases. Poliovirus nonpermissive cells derived from the RD cell line did not show CD155-specific cell-surface immunofluorescence. CD155 gene sequencing confirmed nucleotide base pair deletions within exon2 and exon3. The CD155 knockout RD-SJ40 cells did not support the growth of poliovirus from positive stool samples. All NPEV types were isolated in RD and RD-SJ40 cells. CRISPR correctly edited the CD155 gene of RD cells to render them poliovirus nonpermissive while susceptibility to NPEV remained unchanged. RD-SJ40 cells are safe for NPEV isolation from poliovirus PIM without derogating GAP III containment requirements.

Expansion of the measles and rubella laboratory network, India.

Objective: To expand the measles and rubella laboratory network of India by integrating new laboratories. Methods: In collaboration with the World Health Organization (WHO), the Indian government developed a 10-step scheme to systematically expand the number of laboratories performing serological and molecular testing for measles and rubella. The Indian Council of Medical Research and WHO identified suitable laboratories based on their geographical location, willingness, preparedness, past performance and adherence to national quality control and quality assurance mechanisms. The 10-step scheme was initiated with training on measles and rubella diagnostic assays followed by testing of both measles and rubella serology and molecular unknown panels, cross-verification with reference laboratories and ended with WHO on-site accreditation. Findings: After extensive training, technical support, funding and monitoring, all six selected laboratories attained passing scores of 90.0% or more in serological and molecular proficiency testing of measles and rubella. Since 2018, the laboratories are a part of the measles and rubella network of India. Within 12 months of initiation of independent reporting, the six laboratories have tested 2287 serum samples and 701 throat or nasopharyngeal swabs or urine samples. Conclusion: The process led to strengthening and expansion of the network. This proficient laboratory network has helped India in scaling up serological and molecular testing of measles and rubella while ensuring high quality testing. The collaborative model developed by the Indian government with WHO can be implemented by other countries for expanding laboratory networks for surveillance of measles and rubella as well as other infectious diseases.

Serological, molecular and clinical correlates of dengue from a tertiary care centre in Chennai, India.

Dengue disease is caused by dengue viruses 1-4 and has been ranked by the World Health Organisation (WHO) as the fastest spreading vector-borne viral disease. Dengue is often underreported and misdiagnosed due to a wide spectrum of clinical manifestations. Diagnosis of dengue is based on clinical case definitions and laboratory methods. Newer case definitions of dengue have been formulated by clinical studies in order to improve case detection. Owing to its epidemic potential, mortality and morbidity, there is a need for a rapid and accurate diagnostic assay for dengue in order to help the clinician in the early detection of cases and to prevent disease progression. A duplex real time PCR targeting the 3'UTR region for rapid and simultaneous detection of all dengue viruses serotypes (1-4) was standardized based on published literature. About 150 patients with acute undifferentiated febrile illness classified based on the 2009 WHO dengue case definition were tested using the duplex real time dengue PCR. Sequencing based PCR was performed on selected PCR positive samples for partial nucleotide sequence of the CprM gene and a phylogenetic tree was constructed. Statistical analysis was done using the MedCalc software. Out of the 126 patients classified as dengue disease positive, according to the 2009 WHO dengue case definition, 54% had "probable dengue", 43% had "dengue with warning signs" and 3% had "severe dengue". The performance of the duplex real time PCR was assessed among the various clinical groups of dengue and it was found that in the "dengue with warning signs group" PCR had a positive predictive value of 85.29% (range - 68.94% to 95.05%) when compared with dengue NS1 ELISA. The average time for PCR positivity was found to be four days from the onset of illness. The cycling threshold values obtained from real time PCR were used as a semi quantitative measure of viremia. Accordingly, there was a relatively low CT value among the "warning signs dengue group" when compared to the "probable dengue group". The use of the duplex PCR is suggested in the early diagnosis of dengue, especially in the 'warning signs' group of patients as they showed a higher positivity rate. Also, the use of the resultant CT value as a semi-quantitative measure of viremia will assist the clinician in early diagnosis and prevention of disease development.

A novel indirect ELISA for diagnosis of dengue fever.

BACKGROUND & OBJECTIVES: Dengue fever (DF) is associated with significant morbidity and mortality in the tropical and sub-tropical regions of the world. Since there are no effective antiviral drugs for treatment, clinicians often rely on the accurate diagnosis of dengue fever to begin supportive therapy at early stages of the illness. The objective of this study was to develop an in-house dengue virus serotype 2 (DENV-2) non-structural protein- 5 (NS5) based indirect ELISA. METHODS: DENV-2 was raised in Vero cells and the viral proteins were separated and subsequently the NS5 protein was eluted. Serum samples from primary and secondary dengue fever patients; and acute and convalescent samples from Japanese encephalitis (JE) and West Nile virus (WNV) cases were used to validate the ELISA. RESULTS: The assay was found to be 100 per cent specific in detecting DENV-2 specific antibodies from patient's serum. However, in terms of sensitivity, the assay could detect IgM antibodies only from 90 per cent of the primary dengue samples. The IgM/IgG ratio of the primary and secondary samples was 7.24 and 0.64, respectively. INTERPRETATION & CONCLUSIONS: The results indicate that the DENV-2 NS5 ELISA is dengue group specific and can be used to differentiate dengue infection from other circulating Flavivirus infections. This NS5 ELISA can also be used to distinguish between primary and secondary dengue fever on the basis of IgM/IgG ratios. Further studies with larger sample sizes and different DENV serotypes are required to validate the ELISA.

Evolution and Phylodynamics of the Hemagglutinin Protein of Influenza A/(H1N1)pdm09 Virus Isolates from India from 2009 to 2020.

Influenza A/(H1N1)pdm09 virus evolves through continuous antigenic variation in both surface antigens, such as hemagglutinin (HA) and neuraminidase (NA) proteins, which affect its pathogenicity, the effectiveness of the host immune response, and drug resistance. This study reports the evolution and dynamics of 527 HA protein sequences of influenza A/(H1N1)pdm09 Indian isolates submitted from 2009 to 2020. These isolates were aligned with a reference sequence and 22 sequences representing different clades using MEGA X, and subjected to phylogenetic analysis. The strains were predominantly grouped in clades 6B.1 and 6B.2. Prediction of glycosylation sites using the BioEdit and NetNglyc servers showed 12 glycosylation sites distributed in both the stem and globular head regions of HA. Functional evaluation showed that there were 22 deleterious mutations that could affect the function of HA. In addition, 403 unique mutations were distributed across various isolates, indicating the dynamics of antigenic variation in Indian isolates. These results provide an understanding of the frequency, phylodynamics, and impact of mutations in Indian isolates of influenza A/(H1N1)pdm09 relative to global isolates. Monitoring the genomic evolution of the virus will support studies on strain selection for vaccine development and devising control and prevention measures to manage this respiratory infection.

Etiological Profile and Clinico Epidemiological Patterns of Acute Encephalitis Syndrome in Tamil Nadu, India.

Introduction: Establishing the etiological cause of acute encephalitis syndrome (AES) is challenging due to the distinct distribution of various etiological agents. This study aims to determine the etiological profiles of both viruses and bacteria and their associated clinico-epidemiological features among the AES suspected cases in Tamil Nadu, India. Methods: Samples of 5136 suspected AES cases from January 2016 to December 2020 (5 years) were subjected to the detection of etiological agents for AES through serological and molecular diagnosis methods. Further, the clinical profile, age- and gender-wise susceptibility of cases, co-infection with other AES etiological agents, and seasonality pattern with respect to various etiological agents were examined. Results: AES positivity was established in 1480 cases (28.82%) among the 5136 suspected cases and the positivity for male and female groups were 57.77% and 42.23%, respectively. The pediatric group was found to be more susceptible than others. Among the etiological agents tested, the Japanese encephalitis virus (JEV) was the predominant followed by Cytomegalovirus, Herpes Simplex virus, Epstein-Barr virus, Varicella Zoster virus, and others. Co-infection with other AES etiological agents was observed in 3.5% of AES-positive cases. Seasonality was observed only for vector-borne diseases such as JEV, dengue virus, and West Nile virus infections in this study. Conclusion: AES was found to be a significant burden for Tamil Nadu with a diverse etiological spectrum including both sporadic and outbreak forms. Overlapping clinical manifestations of AES agents necessitate the development of region-specific diagnostic algorithm with distinct etiological profiles for early detection and effective case management.

Epitope Identification and Designing a Potent Multi-epitope Vaccine Construct against SARS-CoV-2 Including the Emerging Variants.

Introduction: The emergence of a novel coronavirus in China has turned into a SARS-CoV-2 pandemic with high fatality. As vaccines are developed through various strategies, their immunogenic potential may drastically vary and thus pose several challenges in offering immune responses against the virus. Methods: In this study, we adopted an immunoinformatics-aided approach for developing a new multi-epitope vaccine construct (MEVC). In silico approach was taken for the identification of B-cell and T-cell epitopes in the Spike protein, for MEVC various cytotoxic T-lymphocyte, helper T-lymphocyte, and B-cell epitopes with the highest affinity for the respective HLA alleles were assembled and joined by linkers. Results: The computational data suggest that the MEVC is nontoxic, nonallergenic and thermostable and elicit both humoral and cell-mediated immune responses. Subsequently, the biological activity of MEVC was assessed by bioinformatic tools using the interaction between the vaccine candidate and the innate immune system receptors TLR3 and TLR4. The epitopes of the construct were analyzed with that of the strains belonging to various clades including the emerging variants having multiple unique mutations in S protein. Conclusions: Due to the advantageous features, the MEVC can be tested in vitro for more practical validation and the study offers immense scope for developing a potential vaccine candidate against SARS-CoV-2 in view of the public health emergency associated with COVID-19 disease caused by SARS-CoV-2.

Phylodynamic Pattern of Genetic Clusters, Paradigm Shift on Spatio-Temporal Distribution of Clades, and Impact of Spike Glycoprotein Mutations of SARS-CoV-2 Isolates from India.

INTRODUCTION: The COVID-19 pandemic is associated with high morbidity and mortality, with the emergence of numerous variants. The dynamics of SARS-CoV-2 with respect to clade distribution is uneven, unpredictable and fast changing. METHODS: Retrieving the complete genomes of SARS-CoV-2 from India and subjecting them to analysis on phylogenetic clade diversity, Spike (S) protein mutations and their functional consequences such as immune escape features and impact on infectivity. Whole genome of SARS-CoV-2 isolates (n = 4,326) deposited from India during the period from January 2020 to December 2020 is retrieved from Global Initiative on Sharing All Influenza Data (GISAID) and various analyses performed using in silico tools. RESULTS: Notable clade dynamicity is observed indicating the emergence of diverse SARS-CoV-2 variants across the country. GR clade is predominant over the other clades and the distribution pattern of clades is uneven. D614G is the commonest and predominant mutation found among the S-protein followed by L54F. Mutation score prediction analyses reveal that there are several mutations in S-protein including the RBD and NTD regions that can influence the virulence of virus. Besides, mutations having immune escape features as well as impacting the immunogenicity and virulence through changes in the glycosylation patterns are identified. CONCLUSIONS: The study has revealed emergence of variants with shifting of clade dynamics within a year in India. It is shown uneven distribution of clades across the nation requiring timely deposition of SARS-CoV-2 sequences. Functional evaluation of mutations in S-protein reveals their significance in virulence, immune escape features and disease severity besides impacting therapeutics and prophylaxis.

Comparison of Cytokine Expression Profile in Chikungunya and Dengue Co-Infected and Mono-Infected Patients' Samples.

Chikungunya (CHIKV) and Dengue (DENV) viruses cause an acute febrile illness which is hard to clinically differentiate and treat since both exhibit similar symptoms. Hence, this study was aimed at identifying the expression profiles of cytokines on co-infected samples and compare with CHIKV and DENV mono-infected samples. Serum samples of 292 suspected patients during 2009-2011 were analyzed. The presence of primary (IgM)/secondary (IgG) antibodies and early NS1 Dengue antigens were confirmed by capture ELISA. Molecular diagnosis and serotypes were discriminated by RT-PCR, confirmed by sequencing. All the plasma samples were assayed for cytokine expression by BDTM cytometry bead array (CBA) and compared with independent mono-infection viral load. Among the tested samples, 82 were confirmed as Dengue positive; 52 through IgM (17.8%), and 30 through IgG (10.2%). Additionally, 186 samples were confirmed as Chikungunya, 96 through IgM (32.6%) and 92 through IgG (31.5%) ELISA, respectively. Interestingly, 19 patients were co-infection positive in which, only 6 were confirmed for CHIKV and 7 for DENV by RT-PCR. Among 8 cytokines, IL-2, IL-8, IFNα, IFN γ, and IL-12 were found to be significantly different between co-infected and CHIKV mono-infected patients and correlated with viral load. DENV viral load was correlated with cytokine expression and a significant difference in IL-2 and IL-12 was observed between DENV mono-infected and DENV and CHIKV co-infected patients. Results indicated that apart from serological and molecular confirmation, cytokines could be used as a specific biomarker for the diagnosis of DENV and CHIKV. In the future, the role of independent cytokines can be determined to understand the pathogenesis and etiology of these dreadful diseases.

An Epidemiological Analysis of SARS-CoV-2 Genomic Sequences from Different Regions of India.

The number of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) cases is increasing in India. This study looks upon the geographic distribution of the virus clades and variants circulating in different parts of India between January and August 2020. The NPS/OPS from representative positive cases from different states and union territories in India were collected every month through the VRDLs in the country and analyzed using next-generation sequencing. Epidemiological analysis of the 689 SARS-CoV-2 clinical samples revealed GH and GR to be the predominant clades circulating in different states in India. The northern part of India largely reported the 'GH' clade, whereas the southern part reported the 'GR', with a few exceptions. These sequences also revealed the presence of single independent mutations-E484Q and N440K-from Maharashtra (first observed in March 2020) and Southern Indian States (first observed in May 2020), respectively. Furthermore, this study indicates that the SARS-CoV-2 variant (VOC, VUI, variant of high consequence and double mutant) was not observed during the early phase of virus transmission (January-August). This increased number of variations observed within a short timeframe across the globe suggests virus evolution, which can be a step towards enhanced host adaptation.

Anti-chikungunya activity of luteolin and apigenin rich fraction from Cynodon dactylon.

OBJECTIVE: To obtain luteolin and apigenin rich fraction from the ethanolic extract of Cynodon dactylon (L.) (C. dactylon) Pers and evaluate the fraction's cytotoxicity and anti-Chikungunya potential using Vero cells. METHODS: The ethanolic extract of C. dactylon was subjected to silica gel column chromatography to obtain anti-chikungunya virus (CHIKV) fraction. Reverse phase-HPLC and GC-MS studies were carried out to identify the major phytochemicals in the fraction using phytochemical standards. Cytotoxicity and the potential of the fraction against CHIKV were evaluated in vitro using Vero cells. Reduction in viral replication was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR) after treating the viral infected Vero cells with the fraction. RESULTS: Reverse Phase-HPLC and GC-MS studies confirmed the presence of flavonoids, luteolin and apigenin as major phytochemicals in the anti-CHIKV ethanolic fraction of C. dactylon. The fraction was found to exhibit potent viral inhibitory activity (about 98%) at the concentration of 50 µg/mL as observed by reduction in cytopathic effect, and the cytotoxic concentration of the fraction was found to be 250 µg/mL. RT-PCR analyses indicated that the reduction in viral mRNA synthesis in fraction treated infected cells was much higher than the viral infected control cells. CONCLUSIONS: Luteolin and apigenin rich ethanolic fraction from C. dactylon can be utilized as a potential therapeutic agent against CHIKV infection as the fraction does not show cytotoxicity while inhibiting the virus.

Development and evaluation of flavi-immunoglobulin M capture enzyme-linked immunosorbent assay.

In this study, we report the evaluation of In-house flavi virus immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (ELISA), which can be used as a screening test to determine the infecting flavivirus serotype over the current serological methods. A panel of 88 sera (inclusive of well characterized dengue, Japanese Encephalitis (JE) and West Nile virus (WNV) positive and negative samples tested and confirmed by commercial kit) was used for evaluation of the kit. The sensitivity and specificity of the In-house capture assay versus the commercial kit for the sero-diagnosis of dengue was 100% and 87% respectively, for JE IgM, it was found to be 90% and 100% respectively, and for West Nile it was 87.5% and 90.9%. Based on the study, we concluded that this flavivirus-serotyping ELISA provides rapid results and may be used as an accurate alternate to other serological tests for the specific diagnosis of flavivirus infections.

Dengue epidemiology in Thanjavur and Trichy district, Tamilnadu--Jan 2011-Dec 2011.

BACKGROUND: Dengue infection is emerging as a serious public health problem in Tamil Nadu. An enhanced surveillance system can generate information on the epidemiology of the disease, which is essential for planning and development of relevant control/preventive measures against Dengue. MATERIALS AND METHODS: A prospective descriptive study was undertaken between January 2011 to December 2011, by testing suspected Dengue patients attending Thanjavur Medical College and Trichy Hospital (TMCH, a major Government referral hospital in Thanjavur District, Tamil Nadu, India) to define the magnitude of Dengue burden, the natural history of this disease in terms of clinical presentation and outcome of the infections in hospitalized Dengue patients. The sera collected from suspected patients were analyzed for Dengue specific IgM and IgG antibodies by IgM antibody capture enzyme linked immunosorbent assay (ELISA) using NIV kit and IgGPanBio Duo Rapid Immunochromatographic Card Test (Brisbane, Australia). The clinical case definition by World Health Organization was adopted to categorize the Dengue cases. RESULTS: The total number of samples screened during the period was 200, out of which 79 (39.5%) were positive for IgM and IgG antibodies and 65 (32%) for IgM antibodies only. By clinical evaluation, Dengue fever was diagnosed in 43 patients, 18 had hemorrhagic manifestations and four patients had progressed to DSS. Though (DSS+DHF) was present in 22 patients, all of them recovered well. CONCLUSION: In developing countries like India, building of laboratory with advanced capacity for diagnosis and combat-mode ready preparedness for the management of Dengue cases in emergency situation may reduce Dengue-related mortality.

A novel indirect ELISA for diagnosis of dengue fever.

Background & objectives: Dengue fever (DF) is associated with significant morbidity and mortality in the tropical and sub-tropical regions of the world. Since there are no effective antiviral drugs for treatment, clinicians often rely on the accurate diagnosis of dengue fever to begin supportive therapy at early stages of the illness. The objective of this study was to develop an in-house dengue virus serotype 2 (DENV-2) non-structural protein- 5 (NS5) based indirect ELISA. Methods: DENV-2 was raised in Vero cells and the viral proteins were separated and subsequently the NS5 protein was eluted. Serum samples from primary and secondary dengue fever patients; and acute and convalescent samples from Japanese encephalitis (JE) and West Nile virus (WNV) cases were used to validate the ELISA. Results: The assay was found to be 100 per cent specific in detecting DENV-2 specific antibodies from patient’s serum. However, in terms of sensitivity, the assay could detect IgM antibodies only from 90 per cent of the primary dengue samples. The IgM/IgG ratio of the primary and secondary samples was 7.24 and 0.64, respectively. Interpretation & conclusions: The results indicate that the DENV-2 NS5 ELISA is dengue group specific and can be used to differentiate dengue infection from other circulating Flavivirus infections. This NS5 ELISA can also be used to distinguish between primary and secondary dengue fever on the basis of IgM/IgG ratios. Further studies with larger sample sizes and different DENV serotypes are required to validate the ELISA.

Anti-chikungunya activity of luteolin and apigenin rich fraction from Cynodon dactylon

Objective:To obtain luteolin and apigenin rich fraction from the ethanolic extract ofCynodon dactylon (L.) (C. dactylon) Pers and evaluate the fraction’s cytotoxicity and anti-Chikungunya potential using Vero cells.Methods:The ethanolic extract ofC. dactylon was subjected to silica gel column chromatography to obtain anti-chikungunya virus (CHIKV) fraction. Reverse phase-HPLC and GC-MS studies were carried out to identify the major phytochemicals in the fraction using phytochemical standards. Cytotoxicity and the potential of the fraction against CHIKV were evaluatedin vitrousing Vero cells. Reduction in viral replication was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR) after treating the viral infected Vero cells with the fraction.Results:Reverse Phase-HPLC and GC-MS studies confirmed the presence of flavonoids, luteolin and apigenin as major phytochemicals in the anti-CHIKV ethanolic fraction ofC. dactylon. The fraction was found to exhibit potent viral inhibitory activity (about 98%) at the concentration of 50 μg/mL as observed by reduction in cytopathic effect, and the cytotoxic concentration of the fraction was found to be 250 μg/mL. RT-PCR analyses indicated that the reduction in viral mRNA synthesis in fraction treated infected cells was much higher than the viral infected control cells.Conclusions:Luteolin and apigenin rich ethanolic fraction fromC. dactylon can be utilized as a potential therapeutic agent against CHIKV infection as the fraction does not show cytotoxicity while inhibiting the virus.

Development and evaluation of flavi-immunoglobulinM capture enzyme-linked immunosorbent assay.

In this study, we report the evaluation of In-house fl avi virus immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (ELISA), which can be used as a screening test to determine the infecting fl avivirus serotype over the current serological methods. A panel of 88 sera (inclusive of well characterized dengue, Japanese Encephalitis (JE) and West Nile virus (WNV) positive and negative samples tested and confi rmed by commercial kit) was used for evaluation of the kit. The sensitivity and specifi city of the In-house capture assay versus the commercial kit for the sero-diagnosis of dengue was 100% and 87% respectively, for JE IgM, it was found to be 90% and 100% respectively, and for West Nile it was 87.5% and 90.9%. Based on the study, we concluded that this fl avivirus-serotyping ELISA provides rapid results and may be used as an accurate alternate to other serological tests for the specifi c diagnosis of fl avivirus infections.

Dengue epidemiology in Thanjavur and Trichy district, Tamilnadu - Jan 2011-Dec 2011.

Background: Dengue infection is emerging as a serious public health problem in Tamil Nadu. An enhanced surveillance system can generate information on the epidemiology of the disease, which is essential for planning and development of relevant control/preventive measures against Dengue. Materials and Methods: A prospective descriptive study was undertaken between January 2011 to December 2011, by testing suspected Dengue patients attending Thanjavur Medical College and Trichy Hospital (TMCH, a major Government referral hospital in Thanjavur District, Tamil Nadu, India) to define the magnitude of Dengue burden, the natural history of this disease in terms of clinical presentation and outcome of the infections in hospitalized Dengue patients. The sera collected from suspected patients were analyzed for Dengue specific IgM and IgG antibodies by IgM antibody capture enzyme linked immunosorbent assay (ELISA) using NIV kit and IgGPanBio Duo Rapid Immunochromatographic Card Test (Brisbane, Australia). The clinical case definition by World Health Organization was adopted to categorize the Dengue cases. Results: The total number of samples screened during the period was 200, out of which 79 (39.5%) were positive for IgM and IgG antibodies and 65 (32%) for IgM antibodies only. By clinical evaluation, Dengue fever was diagnosed in 43 patients, 18 had hemorrhagic manifestations and four patients had progressed to DSS. Though (DSS + DHF) was present in 22 patients, all of them recovered well. Conclusion: In developing countries like India, building of laboratory with advanced capacity for diagnosis and combat-mode ready preparedness for the management of Dengue cases in emergency situation may reduce Dengue-related mortality.