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

Immune profile and responses of a novel dengue DNA vaccine encoding an EDIII-NS1 consensus design based on Indo-African sequences

The ongoing COVID-19 pandemic highlights the need to tackle viral variants, expand the number of antigens, and assess diverse delivery systems for vaccines against emerging viruses. In the present study, a DNA vaccine candidate was generated by combining in tandem envelope protein domain III (EDIII) of dengue virus serotypes 1-4 and a dengue virus (DENV)-2 non-structural protein 1 (NS1) protein-coding region. Each domain was designed as a serotype-specific consensus coding sequence derived from different genotypes based on the whole genome sequencing of clinical isolates in India and complemented with data from Africa. This sequence was further optimized for protein expression. In silico structural analysis of the EDIII consensus sequence revealed that epitopes are structurally conserved and immunogenic. The vaccination of mice with this construct induced pan-serotype neutralizing antibodies and antigen-specific T cell responses. Assaying intracellular interferon (IFN)-γ staining, immunoglobulin IgG2(a/c)/IgG1 ratios, and immune gene profiling suggests a strong Th1-dominant immune response. Finally, the passive transfer of immune sera protected AG129 mice challenged with a virulent, non-mouse-adapted DENV-2 strain. Our findings collectively suggest an alternative strategy for dengue vaccine design by offering a novel vaccine candidate with a possible broad-spectrum protection and a successful clinical translation either as a stand alone or in a mix and match strategy.

Molecular Characterization and Identification of Potential Inhibitors for 'E' Protein of Dengue Virus

Dengue is an arthropod-borne acute febrile illness caused by Dengue Virus (DENV), a member of Flaviviridae. Severity of the infection ranges from mild self-limiting illness to severe life-threatening hemorrhagic fever (DHF) and dengue shock syndrome (DSS). To date, there is no specific antiviral therapy established to treat the infection. The current study reports the epidemiology of DENV infections and potential inhibitors of DENV 'E' protein. Among the various serotypes, DENV-2 serotype was observed more frequently, followed by DENV-4, DENV-1, and DENV-3. New variants of existing genotypes were observed in DENV-1, 2, and 4 serotypes. Predominantly, the severe form of dengue was attributable to DENV-2 infections, and the incidence was more common in males and pediatric populations. Both the incidence and the disease severity were more common among the residents of non-urban environments. Due to the predominantly self-limiting nature of primary dengue infection and folk medicine practices of non-urban populations, we observed a greater number of secondary dengue cases than primary dengue cases. Hemorrhagic manifestations were more in secondary dengue in particularly in the pediatric group. Through different computational methods, ligands RGBLD1, RGBLD2, RGBLD3, and RGBLD4 are proposed as potential inhibitors in silico against DENV-1, -2, -3, and -4 serotypes.

Towards Integrated Management of Dengue in Mumbai

With increasing urbanisation, the dengue disease burden is on the rise in India, especially in large cities such as Mumbai. Current dengue surveillance in Mumbai includes municipal corporation carrying out specific activities to reduce mosquito breeding sites and the use of insecticides to suppress the adult mosquito populations. Clinical cases remain either underreported or misreported due to the restriction to government clinics, missing the large private health care sector. There is a need for an integrated approach to manage dengue outbreaks in Mumbai. There are various novel strategies available for use that can be utilised to improve disease detection, mosquito surveillance, and control of mosquito-borne diseases. These novel technologies are discussed in this manuscript. Given the complex ecosystem of mosquito-borne diseases in Mumbai, integrating data obtained from these technologies would support the ongoing mosquito control measures in Mumbai.

Severe Dengue Epidemic, Sri Lanka, 2017

In 2017, a dengue epidemic of unexpected magnitude occurred in Sri Lanka. A total of 186,101 suspected cases and 440 dengue-related deaths occurred. We conducted a comprehensive analysis of this epidemic by comparing national surveillance data for 2017 with data from the preceding 5 years. In all Sri Lanka districts, dengue incidence in 2017 increased significantly over incidence during the previous 5 years. Older schoolchildren and young adults were more clinically symptomatic than those at extremes of age. Limited virologic surveillance showed the dominant circulating variant was dengue virus type 2 cosmopolitan genotype in the most affected district. One quarter of total annual cases were reported 5 weeks after the southwest monsoon started. Changes in vector abundance were not predictive of the increased incidence. Direct government expenditures on dengue control activities in 2017 were US $12.7 million. The lessons learned from this outbreak are useful for other tropical nations facing increasing dengue incidence.

Prevalence of Dengue Serotypes and Its Correlation With the Laboratory Profile at a Tertiary Care Hospital in Northwestern India

Background and aim Dengue fever is an emerging arboviral public health problem in a large endemic population in the tropical and sub-tropical areas of the world, with varying degrees of clinical presentation. This study was aimed at analyzing the clinical and laboratory dynamics of the four dengue serotypes. Methods This institutional review board (IRB)-approved hospital-based observational study was performed with 100 in-patients with dengue infection above 12 years of age, without co-morbidities or known malignancy, in a tertiary care center in Northern India. Results Out of 100 patients, four had concurrent infection with two serotypes. Dengue virus serotype-2 (DENV 2) was the most common serotype (34%) and had the maximum percentage of cases of severe dengue (20.6%). The mean total leukocyte count did not differ between the serotypes. DENV 4 had a significantly higher mean neutrophil percentage and a significantly lower mean lymphocyte percentage than DENV 1 (p-value 0.001 and 0.02, respectively), with a higher percentage of cases of severe dengue (20% vs 14.3%, non-significant). Thrombocytopenia was present in all serotypes of infection. There was a significant difference in the derangement of liver function in DENV 2, 3, and 4 as compared to DENV 1. Mean serum albumin levels were significantly lower in DENV 3 and 4 infections. Cases with co-infection had a much higher derangement of liver function and lower mean serum albumin than infections with a single serotype. The mean blood urea and creatinine levels were in the normal range for all serotypes. No mortality occurred in our study. Conclusion DENV 2 is the most common serotype with maximum severity at our hospital. DENV 2 and DENV 4 have a high percentage of cases with severe dengue (20.6% and 20%, respectively). The mean lymphocyte percentage was significantly lower while hepatic involvement and hypoalbuminemia were greater in DENV 4. Initial serotyping in patients with dengue can help monitor the epidemiological trends and help estimate the clinical and laboratory trends of the different serotypes of dengue infection. Particular care should be taken in patients with co-infection.

Outbreaks of dengue in Central India in 2016: Clinical, laboratory & epidemiological study

Background & objectives:

Dengue virus (DENV) causes outbreaks and sporadic cases in tropical and subtropical countries. Documenting intricacies of DEN outbreaks is important for future interventions. The objective of this study was to report clinical, laboratory and epidemiological features of DEN outbreaks reported in different districts of Central India in 2016.

Methods:

In 2016, outbreaks (n=4) suspected of DEN were investigated by rapid response team. Door-to-door fever and entomological surveys were conducted. Blood samples were collected and tested using NS1 or IgM ELISA; real-time reverse transcription-polymerase chain reaction was done to identify serotypes of DEN virus (DENV). NS1-positive samples were tested for the presence of IgG by ELISA. Clinical and demographic data were collected and analyzed.

Results:

Outbreaks occurred in both urban and rural areas in monsoon season and Aedes aegypti was identified as the vector. Fever, chills, headache and myalgia were the major symptoms; no fatality was recorded. Of the 268 DEN suspects, 135 (50.4%) were found serologically positive. DEN positivity was higher (n=75; 55.56%) among males and in the age group of 16-45 yr (n=78; 57.8%). DENV 3 followed by DENV 2 were detected as the major responsible serotypes. High attack rates (up to 38/1000) and low cumulative IgG prevalence (14.9%) were recorded in rural areas.

Interpretation & conclusions:

Our study showed that DENV 3 was the major serotype responsible for outbreaks that occurred in monsoon. High attack rates and lower number of secondary infections in rural areas indicated that DENV is emerging in rural parts of Central India. Early diagnosis at local level and timely intervention by mosquito control activities are needed to avoid such outbreaks in future.

Incidence of dengue illness among children in an urban setting in South India: A population based study

OBJECTIVES

Our main objective was to estimate population based dengue incidence estimates in children with fever >3 days.

METHODS

The study used the 'National Surveillance System for Enteric Fever in India' (NSSEFI) cohort at the Vellore site. Children aged 6 months to 14 years from a peri-urban setting in Vellore were followed up for a year for the presence of fever. All children who had fever >3days were eligible for blood culture to diagnose typhoid. All children that presented with fever >3days on alternate days of the week were also tested for dengue. Dengue incidence estimates were then calculated.

RESULTS

There were 6648 children followed up with a cumulative observation period of 5800 child years. There were 11753 fever episodes with 3171 (27%) episodes lasting >3 days. Totally, 784 children with 868 episodes of fever were tested for Dengue. NS1 antigen or Dengue IgM or both were positive in 82 (9.4%) of those tested for Dengue. Dengue PCR was positive in 33/64 (51.6%) of the samples positive samples. The annual incidence rate of dengue was 49.5 per 1000 child years among children with fever >3 days.

CONCLUSIONS

There is high burden of dengue in peri-urban Vellore.

Co-circulation of four dengue serotypes at South Eastern Andhra Pradesh, India: A prospective study

Background

Dengue is one of the most important mosquito-borne viral diseases in the world. The emergence and spread of four dengue viruses (DENVs) (serotypes) represent a global pandemic. The four distinct serotypes are, namely, DENV-1, DENV-2, DENV-3 and DENV-4. Very few dengue serotyping studies have been reported from Andhra Pradesh. In this context, the present study focuses on the circulating serotypes of dengue in South-Eastern Andhra Pradesh.

Methodology

Study was done at Sri Venkateswara Institute of Medical Sciences, a teaching hospital in Tirupati, Andhra Pradesh. Acute phase dengue serum samples were collected and tested for NS1 antigen and anti-human IgM antibodies by enzyme-linked immunosorbent assay (ELISA). NS1-positive samples were further serotyped by reverse transcriptase real-time polymerase chain reaction (rRT-PCR).

Results

A total of 398 serum samples were received from clinically suspected dengue fever cases. Of these, 150 (37.7%) samples were positive for NS1 and/or IgM ELISA. The 96 NS1 antigen-positive samples were further processed for serotyping, of which 36 were negative by rRT-PCR. DENV-2 (41%) was the predominant serotype, followed by DENV-4 (37%), DENV-3 (12%) and DENV-1 (10%) in descending order.

Conclusion

This study reports the all four dengue serotypes' co-circulation. This is the first report from South Eastern Andhra Pradesh. Amongst four, DENV-2 was predominant followed by DENV-4. The information of predominant serotypes can guide in forecasting dengue outbreaks and improving control measures of vectors thus may be helpful in the prevention of outbreaks.