An epidemic of dengue haemorrhagic fever/dengue shock syndrome in tropical India

Dengue infection in India: A systematic review and meta-analysis

INTRODUCTION

Dengue is the most extensively spread mosquito-borne disease; endemic in more than 100 countries. Information about dengue disease burden, its prevalence, incidence and geographic distribution is critical in planning appropriate control measures against dengue fever. We conducted a systematic review and meta-analysis of dengue fever in India.

METHODS

We searched for studies published until 2017 reporting the incidence, the prevalence or case fatality of dengue in India. Our primary outcomes were (a) prevalence of laboratory confirmed dengue infection among clinically suspected patients, (b) seroprevalence in the general population and (c) case fatality ratio among laboratory confirmed dengue patients. We used binomial-normal mixed effects regression model to estimate the pooled proportion of dengue infections. Forest plots were used to display pooled estimates. The metafor package of R software was used to conduct meta-analysis.

RESULTS

Of the 2285 identified articles on dengue, we included 233 in the analysis wherein 180 reported prevalence of laboratory confirmed dengue infection, seven reported seroprevalence as evidenced by IgG or neutralizing antibodies against dengue and 77 reported case fatality. The overall estimate of the prevalence of laboratory confirmed dengue infection among clinically suspected patients was 38.3% (95% CI: 34.8%-41.8%). The pooled estimate of dengue seroprevalence in the general population and CFR among laboratory confirmed patients was 56.9% (95% CI: 37.5-74.4) and 2.6% (95% CI: 2-3.4) respectively. There was significant heterogeneity in reported outcomes (p-values<0.001).

CONCLUSIONS

Identified gaps in the understanding of dengue epidemiology in India emphasize the need to initiate community-based cohort studies representing different geographic regions to generate reliable estimates of age-specific incidence of dengue and studies to generate dengue seroprevalence data in the country.

Impediments of reporting dengue cases in India

Dengue has emerged as one of the most important mosquito-borne, fatal flaviviral disease, apparently expanding as a global health problem. An estimated 3.6 billion people are at risk for dengue, with 50 million infections per year occurring across 100 countries globally. The annual number of dengue fever cases in India is many times higher than it is officially reported. This under reporting would play a major role in the government's decision-making. Underestimating of the disease in India encumbers its people from taking preventive measures, discourages efforts to ensnare the sources of the disease and deliberates efforts for vaccine research. In this article, we highlight the probable impediments of under reporting leading to its impact on national and global public health and also offer key remedies to effectively address the issues across the clinics to the community level.

Evaluation of the diagnostic value of the tourniquet test in predicting severe dengue cases in a population from Belo Horizonte, State of Minas Gerais, Brazil

INTRODUCTION

Dengue is prevalent in many tropical and sub-tropical regions. The clinical diagnosis of dengue is still complex, and not much data are available. This work aimed at assessing the diagnostic accuracy of the tourniquet test in patients with suspected dengue infection and its positivity in different classifications of this disease as reported to the Information System for Notifiable Disease in Belo Horizonte, State of Minas Gerais, Brazil between 2001 and 2006.

METHODS

Cross-section analysis of the diagnostic accuracy of the tourniquet test for dengue, using IgM-anti-DENV ELISA as a gold standard.

RESULTS

We selected 9,836 suspected cases, of which 41.1% were confirmed to be dengue. Classic dengue was present in 95.8%, dengue with complications in 2.5% and dengue hemorrhagic fever in 1.7%. The tourniquet test was positive in 16.9% of classic dengue cases, 61.7% of dengue cases with complications and 82.9% of cases of dengue hemorrhagic fever. The sensitivity and specificity of the tourniquet test were 19.1% and 86.4%, respectively.

CONCLUSIONS

A positive tourniquet test can be a valuable tool to support diagnosis of dengue where laboratory tests are not available. However, the absence of a positive test should not be read as the absence of infection. In addition, the tourniquet test was demonstrated to be an indicator of dengue severity.

Influence of evolutionary events on the Indian subcontinent on the phylogeography of dengue type 3 and 4 viruses

During 1960-80 dengue disease profile in India was mild despite circulation of all four serotypes of dengue virus (DENV). Increase in disease severity with a concomitant change in the population of DENV-1 and 2 have been reported since then. To determine population dynamics of DENV-3 and 4, the envelope (E) gene sequence was determined for 16 Indian isolates of DENV-3 and 11 of DENV-4 and analyzed together with 97 DENV-3 and 43 DENV-4 global sequences. All Indian DENV-3 isolates belonged to genotype III, lineages C, D, E and F. Lineage F was newly identified and represented non-circulating viruses. Three non-conservative amino acid changes in domain I, II & III were identified during the transition from lineages F/E, associated with mild disease, to A-D, associated with severe disease. For DENV-4, the current viruses clustered in genotype I, lineage C, whilst the isolates from 1960s formed the new genotype V. A 1979 Indian isolate of DENV-4 was found to be an inter-genotypic recombinant of Sri Lankan isolate (1978) of genotype I and Indian isolate (1961) of genotype V. The rates of nucleotide substitution and time to the most recent common ancestor (tMRCA) estimated for DENV-3 (1782-1934) and DENV-4 (1719-1931) were similar to earlier reports. However, the divergence time for genotype III of DENV-3, 1938-1963, was a more accurate estimate with the inclusion of Indian isolates from the 1960s. By phylogeographical analysis it was revealed that DENV-3 GIII viruses emerged from India and evolved through Sri Lanka whilst DENV-4 emerged and dispersed from India. The present study demonstrates the crucial role that India/Sri Lanka have played in the evolution and dispersion of the major genotypes, GIII of DENV-3 and GI of DENV-4 which are more virulent and show higher dissemination potential.

Risk factors of dengue shock syndrome in children

This retrospective hospital-based study was conducted to evaluate the various risk factors associated with dengue shock syndrome (DSS) in patients (≤18 years of age) of dengue hemorrhagic fever (DHF). Medical records of these 483 patients with DHF (IgM serology positive) were analyzed with reference to shock for various clinical and biochemical parameters. Of the 483 children, 405 were categorized in DHF group (grade I, 282 children; grade II, 123 children) and 78 in DSS group (grade III, 59 children; grade IV, 19 children). Using univariate and multivariate logistic regression and p-value of <0.05 as significant, the presence of spontaneous bleeding, hepatomegaly, signs of capillary leakage like ascitis and pleural effusion, leucopenia <4000 mm(3) and age >5 years were found out to be significant risk factors of shock in pediatrics patients of DHF.

Classifying dengue: a review of the difficulties in using the WHO case classification for dengue haemorrhagic fever

BACKGROUND

The current World Health Organisation (WHO) classification of dengue includes two distinct entities: dengue fever (DF) and dengue haemorrhagic fever (DHF)/dengue shock syndrome; it is largely based on pediatric cases in Southeast Asia. Dengue has extended to different tropical areas and older age groups. Variations from the original description of dengue manifestations are being reported.

OBJECTIVES

To analyse the experience of clinicians in using the dengue case classification and identify challenges in applying the criteria in routine clinical practice.

METHOD

Systematic literature review of post-1975 English-language publications on dengue classification.

RESULTS

Thirty-seven papers were reviewed. Several studies had strictly applied all four WHO criteria in DHF cases; however, most clinicians reported difficulties in meeting all four criteria and used a modified classification. The positive tourniquet test representing the minimum requirement of a haemorrhagic manifestation did not distinguish between DHF and DF. In cases of DHF thrombocytopenia was observed in 8.6-96%, plasma leakage in 6-95% and haemorrhagic manifestations in 22-93%. The low sensitivity of classifying DHF could be due to failure to repeat the tests or physical examinations at the appropriate time, early intravenous fluid therapy, and lack of adequate resources in an epidemic situation and perhaps a considerable overlap of clinical manifestations in the different dengue entities.

CONCLUSION

A prospective multi-centre study across dengue endemic regions, age groups and the health care system is required which describes the clinical presentation of dengue including simple laboratory parameters in order to review and if necessary modify the current dengue classification.