Geographical Distribution Of Dengue Research Articles

Causes of Vision Loss Associated with Dengue Fever in Bihar, India - A Case Series.

The incidence and geographic distribution of dengue has increased dramatically in recent years across various parts of the world. Previously, ocular findings in dengue fever were considered rare. We report a spectrum of ocular manifestations presenting with vision loss in the last dengue epidemic in an eastern state of India. This is a retrospective interventional case series of patients with vision loss who were diagnosed with dengue eye disease in the 2022 epidemic. Systemic and ophthalmic examinations were completed on all patients and were analyzed. Fifteen patients had presented with vision loss. The mean age was 41.7 ± 10.8 years, and patients were mostly males. Three patients presented with panophthalmitis and orbital cellulitis. Eight patients were diagnosed with optic neuropathy. Four patients had macular involvement: macular chorioretinitis, macular subhyaloid hemorrhage, and macular hemorrhages in two patients. All patients with optic neuropathy gave a history of mild fever and had remained undiagnosed. The rest had been diagnosed with the more severe dengue hemorrhagic fever. Vision recovered partially or fully in patients with optic neuropathy and macular disease. No eye could be salvaged in any panophthalmitis patients. Thrombocytopenia (platelet count <100 × 109 per liter of blood) was significantly associated with ocular hemorrhage and panophthalmitis, but thrombocytopenia was not significantly seen in optic neuropathy. We conclude that optic neuropathy may be an underreported cause of vision loss in dengue fever. An eye examination is advocated in all patients with dengue eye disease.

Vector Control Interventions to Prevent Dengue: Current Situation and Strategies for Future Improvements to Management of Aedes in India

Dengue is the most widespread vector-borne infectious disease of humans, existing in around 125 tropical and subtropical countries worldwide. The causative agent, a Flavirus, is transmitted from one person to another by female mosquitoes of the genus Aedes, primarily Ae. aegypti and Ae. albopictus, which breed in small, still bodies of freshwater such as storage tanks, buckets, plant pots and discarded household waste. Encouraging progress has been made in recent years towards the diagnosis and timely management of this debilitating and sometimes fatal disease. However, in the absence of an antiviral therapy or vaccine that is available and affordable in a low income setting, the means to combat dengue currently rely upon vector control measures that are directed against the immature aquatic stages, larvae and pupae, or adult mosquitoes. Although a number of different methods are in use, vector control has failed to prevent outbreaks from occurring and to avert an expansion of the geographical distribution of dengue. This is due to several limitations of present technologies that relate to dwindling financial resources, development of insecticide resistance, failure of long term sustainability and insufficient community involvement. In this context, there is a pressing need for an evidence-based selection process to determine how best to detect and exterminate the breeding of Aedes mosquitoes. This review considers existing vector control strategies as well as discussing some of the novel approaches that are in preparation, placing particular emphasis on relevance to the worsening public health issue of dengue endemicity in India.

Dengue in Malaysia: Factors Associated with Dengue Mortality from a National Registry.

BackgroundThe increasing incidence and geographical distribution of dengue has had significant impact on global healthcare services and resources. This study aimed to determine the factors associated with dengue-related mortality in a cohort of Malaysian patients.MethodsThis was a retrospective cohort study of patients in the Malaysian National Dengue Registry of 2013. The outcome measure was dengue-related mortality. Associations between sociodemographic and clinical variables with the outcome were analysed using multivariate analysis.ResultsThere were 43 347 cases of which 13081 were serologically confirmed. The mean age was 30.0 years (SD 15.7); 60.2% were male. The incidence of dengue increased towards the later part of the calendar year. There were 92 probable dengue mortalities, of which 41 were serologically confirmed. Multivariate analysis in those with positive serology showed that increasing age (OR 1.03; CI:1.01–1.05), persistent vomiting (OR 13.34; CI: 1.92–92.95), bleeding (OR 5.84; CI 2.17–15.70) and severe plasma leakage (OR 66.68; CI: 9.13–487.23) were associated with mortality. Factors associated with probable dengue mortality were increasing age (OR 1.04; CI:1.03–1.06), female gender (OR 1.53; CI:1.01–2.33), nausea and/or vomiting (OR 1.80; CI:1.17–2.77), bleeding (OR 3.01; CI:1.29–7.04), lethargy and/or restlessness (OR 5.97; CI:2.26–15.78), severe plasma leakage (OR 14.72; CI:1.54–140.70), and shock (OR 1805.37; CI:125.44–25982.98), in the overall study population.ConclusionsOlder persons and those with persistent vomiting, bleeding or severe plasma leakage, which were associated with mortality, at notification should be monitored closely and referred early if indicated. Doctors and primary care practitioners need to detect patients with dengue early before they develop these severe signs and symptoms.

Global temperature constraints on Aedes aegypti and Ae. albopictus persistence and competence for dengue virus transmission.

BackgroundDengue is a disease that has undergone significant expansion over the past hundred years. Understanding what factors limit the distribution of transmission can be used to predict current and future limits to further dengue expansion. While not the only factor, temperature plays an important role in defining these limits. Previous attempts to analyse the effect of temperature on the geographic distribution of dengue have not considered its dynamic intra-annual and diurnal change and its cumulative effects on mosquito and virus populations.MethodsHere we expand an existing modelling framework with new temperature-based relationships to model an index proportional to the basic reproductive number of the dengue virus. This model framework is combined with high spatial and temporal resolution global temperature data to model the effects of temperature on Aedes aegypti and Ae. albopictus persistence and competence for dengue virus transmission.ResultsOur model predicted areas where temperature is not expected to permit transmission and/or Aedes persistence throughout the year. By reanalysing existing experimental data our analysis indicates that Ae. albopictus, often considered a minor vector of dengue, has comparable rates of virus dissemination to its primary vector, Ae. aegypti, and when the longer lifespan of Ae. albopictus is considered its competence for dengue virus transmission far exceeds that of Ae. aegypti.ConclusionsThese results can be used to analyse the effects of temperature and other contributing factors on the expansion of dengue or its Aedes vectors. Our finding that Ae. albopictus has a greater capacity for dengue transmission than Ae. aegypti is contrary to current explanations for the comparative rarity of dengue transmission in established Ae. albopictus populations. This suggests that the limited capacity of Ae. albopictus to transmit DENV is more dependent on its ecology than vector competence. The recommendations, which we explicitly outlined here, point to clear targets for entomological investigation.

The role of climate variability and change in the transmission dynamics and geographic distribution of dengue

The mounting evidence for anthropogenic changes in global climate raises many pressing questions about the potential effects on biological systems, and in particular the transmission of infectious diseases. Vector-borne diseases, such as dengue, may be particularly sensitive to both periodic fluctuations and sustained changes in global and local climates, because vector biology and viral replication are temperature- and moisture-dependent. This paper reviews the current state of knowledge on the associations between climate variability, climate change and dengue transmission, and the tools being used to quantify these associations. The underlying causes of dengue's recent global expansion are multifactorial and poorly understood, but climatic factors should be considered within the context of the sociodemographic, economic and immunological determinants that have contributed to dengue's spread. These factors may mediate the direct effects of climate on dengue and many may operate at a very local level. Translating theoretical models of dengue transmission based on historical data into predictive models that can inform public health interventions is a critical next step and efforts should be focused on developing and refining models at smaller spatial scales to characterize the relationships between both climatic and non-climatic factors and dengue risk.

Dengue illness: clinical features and pathogenesis

The incidence and geographical distribution of dengue has gradually increased during the past decade. This review is an update on dengue virus infections, based on our clinical and laboratory experiences in the Philippines and on other relevant literature. The differential diagnosis of this disease is discussed, especially for use by clinicians where dengue is not endemic. The complex pathogenesis of thrombocytopenia and increased vascular permeability in dengue illness is also discussed. Our recent data suggest that platelet-associated immunoglobulins involving anti-dengue virus activity play a pivotal role in the development of dengue hemorrhagic fever (DHF), as well as thrombocytopenia in secondary dengue virus infections. Further elucidation is needed on the involvement of platelet-associated immunoglobulins on the molecular mechanisms of thrombocytopenia and the increased vascular permeability.

Ocular manifestations of dengue fever in an East Indian epidemic

Background: The incidence and geographic distribution of dengue has increased dramatically in recent years. Previously, ocular findings in dengue fever were considered rare. We report a spectrum of ocular manifestations of this potentially fatal disease and its association with laboratory parameters. Methods: 134 patients hospitalized with a diagnosis of dengue fever during an epidemic were included. Systemic and ophthalmic examinations were completed on all patients. Results: The mean age was 31.3 years and 63.4% were males. All patients presented with fever. Six (4.5%) patients had retrobulbar pain and none of the patients presented with any visual complaints. Ocular findings were present in 54 (40.3%) patients. Subconjunctival haemorrhage was the commonest eye finding seen in 50 patients, of whom 84% had characteristic petechial type of haemorrhages. Fundus findings present in 10 (7.5%) patients included dilatation and tortuosity of vessels, superficial retinal haemorrhages, cotton-wool spots, and hard exudates; the macula, however, was spared in all patients. Only 6 of the patients with posterior segment involvement returned for follow-up examination and it was found that retinal changes had resolved without any specific treatment within 2 to 8 weeks time. Of all laboratory parameters evaluated, marked thrombocytopenia (platelet count <50000/µl_) emerged to be significantly associated with ocular haemorrhage. Interpretation: Multiple subconjunctival haemorrhages, especially petechial type, are a common manifestation of dengue infection. Dengue fever patients with marked thrombocytopenia are predisposed to spontaneous ocular haemorrhages.

A Case of Dengue from Pune, India

Dengue is an acute infectious disease, caused by a single stranded ribonucleic acid (RNA) virus of the family of Flaviviridae, genus Flavivirus, transmitted by Aedes mosquitos, the most important vectors being Aedes aegypti and Aedes albopictus. There are four serotypes, DEN-1, DEN-2, DEN-3, DEN-4 that are nearly human specific. The geographical distribution of dengue is pantropical, except for Madagascar and some African regions. It is endemo-epidemic in tropical and subtropical countries included between 25 degrees north latitude and 25 degrees south latitude, particularly in southeast Asia and epidemic in the Caribbean, West-Africa, tropical American and Pacific Islands. Further spread will depend on the invasion of Aedes aegypti into new areas in South America. Maintenance of dengue is supported by an increasing demography, uncontrolled urbanization and climatic conditions favorable to the vectors. Spread of dengue is primarily caused by modern transportation, especially aircraft. No vaccine and no specific treatment exist so that mosquito control is the only way to reduce the incidence of dengue around the world. Dengue is, obviously, an important risk for travelers going to endemic areas.

Ocular manifestations of dengue fever in an East Indian epidemic

Background: The incidence and geographic distribution of dengue has increased dramatically in recent years. Previously, ocular findings in dengue fever were considered rare. We report a spectrum of ocular manifestations of this potentially fatal disease and its association with laboratory parameters. Methods: 134 patients hospitalized with a diagnosis of dengue fever during an epidemic were included. Systemic and ophthalmic examinations were completed on all patients. Results: The mean age was 31.3 years and 63.4% were males. All patients presented with fever. Six (4.5%) patients had retrobulbar pain and none of the patients presented with any visual complaints. Ocular findings were present in 54 (40.3%) patients. Subconjunctival haemorrhage was the commonest eye finding seen in 50 patients, of whom 84% had characteristic petechial type of haemorrhages. Fundus findings present in 10 (7.5%) patients included dilatation and tortuosity of vessels, superficial retinal haemorrhages, cotton-wool spots, and hard exudates; the macula, however, was spared in all patients. Only 6 of the patients with posterior segment involvement returned for follow-up examination and it was found that retinal changes had resolved without any specific treatment within 2 to 8 weeks time. Of all laboratory parameters evaluated, marked thrombocytopenia (platelet count <50000/µl_) emerged to be significantly associated with ocular haemorrhage. Interpretation: Multiple subconjunctival haemorrhages, especially petechial type, are a common manifestation of dengue infection. Dengue fever patients with marked thrombocytopenia are predisposed to spontaneous ocular haemorrhages.

Dengue: an arthropod-borne disease of global importance.

Dengue viruses cause a variable spectrum of disease that ranges from an undifferentiated fever to dengue fever to the potentially fatal dengue shock syndrome. Due to the increased incidence and geographical distribution of dengue in the last 50 years, dengue is becoming increasingly recognised as one of the world's major infectious diseases. This article will review clinical and diagnostic aspects of dengue virus infections. It also presents our current knowledge of the pathophysiology of severe dengue and addresses the importance of dengue virus infections in those travelling to parts of the world where dengue is endemic.