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Background: Dengue is an arboviral disease caused by dengue virus. Symptomatic dengue infection causes a wide range of clinical manifestations, from mild dengue fever (DF) to potentially fatal disease, such as dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). We conducted a literature review to analyze the risks of DHF and current perspectives for DHF prevention and control., Methods: According to the PRISMA guidelines, the references were selected from PubMed, Web of Science and Google Scholar database using search strings containing a combination of terms that included dengue hemorrhagic fever, pathogenesis, prevention and control. Quality of references were evaluated by independent reviewers., Results: DHF was first reported in the Philippines in 1953 and further transmitted to the countries in the region of South-East Asia and Western Pacific. Plasma leakages is the main pathophysiological hallmark that distinguishes DHF from DF. Severe plasma leakage can result in hypovolemic shock. Various factors are thought to impact disease presentation and severity. Virus virulence, preexisting dengue antibodies, immune dysregulation, lipid change and host genetic susceptibility are factors reported to be correlated with the development of DHF. However, the exact reasons and mechanisms that triggers DHF remains controversial. Currently, no specific drugs and licensed vaccines are available to treat dengue disease in any of its clinical presentations., Conclusion: This study concludes that antibody-dependent enhancement, cytokine dysregulation and variation of lipid profiles are correlated with DHF occurrence. Prompt diagnosis, appropriate treatment, active and continuous surveillance of cases and vectors are the essential determinants for dengue prevention and control., Competing Interests: Declaration of competing interest The author reports no conflicts of interest in this work., (Copyright © 2020. Published by Elsevier B.V.)

Background & Objectives: An outbreak of dengue-like illness was reported from Wadi area within the Nagpur Municipal Corporation during September-October 2017 with five deaths. Major symptoms reported were high fever (103-106 o F), acute joint pains, myalgia, drowsiness, breathlessness, etc. An investigation was conducted to confirm the etiological agent, its characterization and the vectors involved in the outbreak., Methods: Serological analysis was conducted to detect dengue (DEN)/chikungunya IgM antibodies in 158 sera samples. Nested-PCR was carried out to serotype eight ELISA positive samples. Adult and larval mosquito collections were conducted in the affected areas to determine species composition and mosquito density., Results: Dengue IgM antibodies were detected in 44 sera samples. Molecular typing revealed involvement of DEN-2 and DEN-3 serotypes. Dengue hemorrhagic fever symptoms were observed in two patients. Aedes aegypti breeding was found rampant with Breteu index and house index ranging from 23 to 70 and 17 to 56, respectively. Major breeding habitats encountered were, used tyres, cement tanks and refrigerator trays., Interpretation & Conclusion: Clinical symptoms, detection of anti-DEN IgM antibodies in high number of samples and heavy breeding of Ae. aegypti confirmed it was a dengue outbreak.

Background: Incidence of Dengue infection is on the increase in Sri Lanka with it being associated with significant maternal and neonatal morbidity in pregnancy., Case Presentation: A 33-year-old pregnant woman at 38 weeks of gestation, presented with acute onset of fever, was later diagnosed with Dengue illness. Due to the emergence of warning symptoms and signs and rapidly dropping platelet count, the baby was delivered by urgent caesarian section. She went into the critical phase during the postoperative period and due to concealed bleeding, required blood transfusion. On the 5th day of life, the neonate was also diagnosed with possible dengue by vertical transmission and required blood and PLT transfusions for recovery., Conclusions: This case report illustrates how a high index of suspicion, early diagnosis, close monitoring, timely intervention and critical consideration of physiological changes of pregnancy when interpreting clinical situation, led to achieving a successful outcome.

Background: A case-cohort study, using a novel assay and data from three dengue vaccine efficacy trials, highlighted differences in vaccination outcomes according to baseline serostatus. Based on these results, we explored, with a model, the benefits and risks associated with vaccination., Research Design and Methods: Parameters of a previously developed transmission model were estimated with subject-level data from a case-cohort study. The model was used to assess vaccination outcomes for a range of transmission settings over 5-30 years, with or without indirect protection., Main Outcome Measures: Symptomatic dengue cases, dengue hospitalizations, and severe dengue cases., Results: The model is consistent with previous results indicating a transitory period at increased risk for dengue-seronegative vaccine recipients (setting-dependent duration) and long-term benefits for dengue-seropositive recipients. At the population level, benefits to seropositive individuals over 10 years outweighed the risk to those seronegative in moderate to high transmission settings (≥50% seropositivity at age 9), especially in high transmission settings (no excess hospitalizations in dengue-seronegative for ≥80% seropositivity at age 9). Results were more favorable when longer time horizons or indirect protection were considered., Conclusions: Results indicate a public health benefit associated with dengue vaccination especially in high-transmission settings, even with the initial excess risks to dengue-seronegative patients which diminish over time.

To determine the association of climatic factors and dengue hemorrhagic fever and to develop the prediction approach of future dengue transmission. The study used totally monthly dengue hemorrhagic fever cases at Health Office Kendari, Southeast Sulawesi, Indonesia. Monthly meteorological data, consisting of temperature, rainfall, and humidity, was obtained from the Meteorology, Climatology and Geophysics Agency in Kendari district. All data analysis, including Spearman and Poisson distribution, was carried out in R Studio (version 3.3.2) utilizing the R statistical language version 2.15. The highest rate of dengue hemorrhagic fever cases was found in January, February, and March. Temperature averages at lag 2 (p = 0.53, p < 0.0001), lag 3 (p = 0.59, p < 0.0001), and lag 4 (p = 0.41, p < 0.01)) correlated with the incident rate of DHF. The average temperature at lag 2 was found to have a positive impact on the incidence of DHF by Poisson function. This study provides preliminary evidence of the influence of climatic factors on dengue transmission.

Background: Mosquito-borne dengue virus (DENV) is maintained in a sylvatic, enzootic cycle of transmission between canopy-dwelling non-human primates and Aedes mosquitoes in Borneo. Sylvatic DENV can spill over into humans living in proximity to forest foci of transmission, in some cases resulting in severe dengue disease. The most likely vectors of such spillover (bridge vectors) in Borneo are Ae. albopictus and Ae. niveus. Borneo is currently experiencing extensive forest clearance. To gauge the effect of this change in forest cover on the likelihood of sylvatic DENV spillover, it is first necessary to characterize the distribution of bridge vectors in different land cover types. In the current study, we hypothesized that Ae. niveus and Ae. albopictus would show significantly different distributions in different land cover types; specifically, we predicted that Ae. niveus would be most abundant in forests whereas Ae. albopictus would have a more even distribution in the landscape., Results: Mosquitoes were collected from a total of 15 sites using gravid traps and a backpack aspirator around Kampong Puruh Karu, Sarawak, Malaysian Borneo, where sylvatic DENV spillover has been documented. A total of 2447 mosquitoes comprising 10 genera and 4 species of Aedes, were collected over the three years, 2013, 2014 and 2016, in the three major land cover types in the area, homestead, agriculture and forest. Mosquitoes were identified morphologically, pooled by species and gender, homogenized, and subject to DNA barcoding of each Aedes species and to arbovirus screening. As predicted, Ae. niveus was found almost exclusively in forests whereas Ae. albopictus was collected in all land cover types. Aedes albopictus was significantly (P = 0.04) more abundant in agricultural fields than forests. Sylvatic DENV was not detected in any Aedes mosquito pools, however genomes of 14 viruses were detected using next generation sequencing., Conclusions: Land cover type affects the abundance and distribution of the most likely bridge vectors of sylvatic DENV in Malaysia Borneo. Conversion of forests to agriculture will likely decrease the range and abundance of Ae. niveus but enhance the abundance of Ae. albopictus.

In recent decades, Dengue fever and its deadly complications, such as Dengue hemorrhagic fever, have become one of the major mosquito-transmitted diseases, with an estimate of 390 million cases occurring annually in over 100 tropical and subtropical countries, most of which belonging to the developing world. Empirical evidence indicates that the most effective mechanism to reduce Dengue infections is to combat the disease-carrying vector, which is often implemented via chemical pesticides to destroy mosquitoes in their adult or larval stages. The present paper considers an SIR epidemiological model describing the vector-to-host and host-to-vector transmission dynamics. The model includes pesticide control represented in terms of periodic impulsive perturbations, as well as seasonal fluctuations of the vector growth and transmission rates of the disease. The effectiveness of the control strategy is studied numerically in detail by means of path-following techniques for non-smooth dynamical systems. Special attention is given to determining the optimal timing of the pesticide applications, in such a way that the number of infections and the required amount of pesticide are minimized., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The neuroteratogenic nature of Zika Virus (ZIKV) infection has converted what would have been a tropical disease into a global threat. Zika is transmitted vertically via infected placental cells especially in the first and second trimesters. In the developing central nervous system (CNS), ZIKV can infect and induce apoptosis of neural progenitor cells subsequently causing microcephaly as well as other neuronal complications in infants. Its ability to infect multiple cell types (placental, dermal, and neural) and increased environmental stability as compared to other flaviviruses (FVs) has broadened the transmission routes for ZIKV infection from vector-mediated to transmitted via body fluids. To further complicate the matters, it is genetically similar (about 40%) with the four serotypes of dengue virus (DENV), so much so that it can almost be called a fifth DENV serotype. This homology poses the risk of causing cross-reactive immune responses and subsequent antibody-dependent enhancement (ADE) of infection in case of secondary infections or for immunized individuals. All of these factors complicate the development of a single preventive vaccine candidate or a pharmacological intervention that will completely eliminate or cure ZIKV infection. We discuss all of these factors in detail in this review and conclude that a combinatorial approach including immunization and treatment might prove to be the winning strategy.

Background: Dengue fever is an important arboviral disease. The clinical manifestations vary from a mild non-specific febrile syndrome to severe life-threatening illness. The virus can usually be detected in the blood during the early stages of the disease. Dengue virus has also been found in isolated cases in the cerebrospinal fluid, urine, nasopharyngeal sections and saliva. In this report, we describe the isolation of dengue virus from the upper respiratory tract of four confirmed cases of dengue., Methods: We reviewed all laboratory reports of the isolation of dengue virus from respiratory specimens at the clinical microbiology laboratory of the Kaohsiung Veterans General Hospital during 2007 to 2015. We then examined the medical records of the cases from whom the virus was isolated to determine their demographic characteristics, family contacts, clinical signs and symptoms, course of illness and laboratory findings., Results: Dengue virus was identified in four patients from a nasopharyngeal or throat culture. Two were classified as group A dengue (dengue without warning signs), one as group B (dengue with warning signs) and one as group C (severe dengue). All had respiratory symptoms. Half had family members with similar respiratory symptoms during the period of their illnesses. All of the patients recovered uneventfully., Conclusions: The isolation of dengue virus from respiratory specimens of patients with cough, rhinorrhea and nasal congestion, although rare, raises the possibility that the virus is capable of transmission by the aerosol route among close contacts. This concept is supported by studies that show that the virus can replicate in cultures of respiratory epithelium and can be transmitted through mucocutaneous exposure to blood from infected patients. However, current evidence is insufficient to prove the hypothesis of transmission through the respiratory route. Further studies will be needed to determine the frequency of respiratory colonization, viable virus titers in respiratory secretions and molecular genetic evidence of transmission among close contacts.

Background: In the past few decades, several researchers have proposed highly accurate prediction models that have typically relied on climate parameters. However, climate factors can be unreliable and can lower the effectiveness of prediction when they are applied in locations where climate factors do not differ significantly. The purpose of this study was to improve a dengue surveillance system in areas with similar climate by exploiting the infection rate in the Aedes aegypti mosquito and using the support vector machine (SVM) technique for forecasting the dengue morbidity rate., Methods and Findings: Areas with high incidence of dengue outbreaks in central Thailand were studied. The proposed framework consisted of the following three major parts: 1) data integration, 2) model construction, and 3) model evaluation. We discovered that the Ae. aegypti female and larvae mosquito infection rates were significantly positively associated with the morbidity rate. Thus, the increasing infection rate of female mosquitoes and larvae led to a higher number of dengue cases, and the prediction performance increased when those predictors were integrated into a predictive model. In this research, we applied the SVM with the radial basis function (RBF) kernel to forecast the high morbidity rate and take precautions to prevent the development of pervasive dengue epidemics. The experimental results showed that the introduced parameters significantly increased the prediction accuracy to 88.37% when used on the test set data, and these parameters led to the highest performance compared to state-of-the-art forecasting models., Conclusions: The infection rates of the Ae. aegypti female mosquitoes and larvae improved the morbidity rate forecasting efficiency better than the climate parameters used in classical frameworks. We demonstrated that the SVM-R-based model has high generalization performance and obtained the highest prediction performance compared to classical models as measured by the accuracy, sensitivity, specificity, and mean absolute error (MAE).

During 2010 and 2011, the Loreto region of Peru experienced a dengue outbreak of unprecedented magnitude and severity for the region. This outbreak coincided with the reappearance of dengue virus-2 (DENV-2) in Loreto after almost 8 years. Whole-genome sequence indicated that DENV-2 from the outbreak belonged to lineage II of the southeast Asian/American genotype and was most closely related to viruses circulating in Brazil during 2007 and 2008, whereas DENV-2 previously circulating in Loreto grouped with lineage I (DENV-2 strains circulating in South America since 1990). One amino acid substitution (NS5 A811V) in the 2010 and 2011 isolates resulted from positive selection. However, the 2010 and 2011 DENV-2 did not replicate to higher titers in monocyte-derived dendritic cells and did not infect or disseminate in a higher proportion of Aedes aegypti than DENV-2 isolates previously circulating in Loreto. These results suggest that factors other than enhanced viral replication played a role in the severity of this outbreak., (© The American Society of Tropical Medicine and Hygiene.)

In 2009, a severe epidemic of dengue disease occurred in Sri Lanka, with higher mortality and morbidity than any previously recorded epidemic in the country. It corresponded to a shift to dengue virus 1 as the major disease-causing serotype in Sri Lanka. Dengue disease reached epidemic levels in the next 3 years. We report phylogenetic evidence that the 2009 epidemic DENV-1 strain continued to circulate within the population and caused severe disease in the epidemic of 2012. Bayesian phylogeographic analyses suggest that the 2009 Sri Lankan epidemic DENV-1 strain may have traveled directly or indirectly from Thailand through China to Sri Lanka, and after spreading within the Sri Lankan population, it traveled to Pakistan and Singapore. Our findings delineate the dissemination route of a virulent DENV-1 strain in Asia. Understanding such routes will be of particular importance to global control efforts., (© The American Society of Tropical Medicine and Hygiene.)

Objective: To describe the case of a patient with term pregnancy and infection with hemorrhagic dengue and vertical transmission to the newborn., Clinical Case: Thirty-two year old patient with pregnancy at 38 weeks was admitted with fever 2 days earlier (38 degrees C). During her stay she continued with fever of 39 degrees C and platelets of 85,000/mm3. Serology for dengue NS1 antigen was reported positive. Labor was induced getting a new-born, male, 3,220 g, who breathed and cried at birth. During the postpartum period continued with fever, malaise, retro-ocular pain, generalized rash in upper and lower limbs, bleeding gums and petechial on the soft palate and thrombocytopenia of 5,000/mm3, later. At 8 days of stay, platelet concentration increased to 42,000/mm3 without requiring platelet concentrates and she was discharged after ten days in hospital with platelets of 94,000/mm3. The 4th day of extra-uterine live (EUL), neonate shows generalized rash over the trunk; The 5th day starts with 38 degrees C fever and thrombocytopenia (78,000/mm3). Dengue serological tests reported positive for Ag NS1 and negative for Abs IgM and IgG. Neonate was admitted to NICU, he continued with a decrease in platelet of 14,000/mm3- and ecchymotic areas by pressure and veno-punction sites. Four platelet concentrates were transfused. At 10th day of EUL platelet count was reported with 387,000/mm3., Conclusions: In an endemic area, such as Sinaloa state, in a pregnant woman with fever and thrombocytopenia, we should be alert to possibility of a DV infection and its complications. Although rare, such as this case, infection can be transmitted to fetus (vertical transmission) and produce a primary congenital dengue, even in its severe hemorrhagic types.

Using a novel analytical approach, weather dynamics and seasonal dengue virus transmission cycles were profiled for each Thailand province, 1983-2001, using monthly assessments of cases, temperature, humidity, and rainfall. We observed systematic differences in the structure of seasonal transmission cycles of different magnitude, the role of weather in regulating seasonal cycles, necessary versus optimal transmission "weather-space," basis of large epidemics, and predictive indicators that estimate risk. Larger epidemics begin earlier, develop faster, and are predicted at Onset change-point when case counts are low. Temperature defines a viable range for transmission; humidity amplifies the potential within that range. This duality is central to transmission. Eighty percent of 1.2 million severe dengue cases occurred when mean temperature was 27-29.5°C and mean humidity was > 75%. Interventions are most effective when applied early. Most cases occur near Peak, yet small reductions at Onset can substantially reduce epidemic magnitude. Monitoring the Quiet-Phase is fundamental in effectively targeting interventions pre-emptively.

Various simple mathematical models have been used to investigate dengue transmission. Some of these models explicitly model the mosquito population, while others model the mosquitoes implicitly in the transmission term. We study the impact of modeling assumptions on the dynamics of dengue in Thailand by fitting dengue hemorrhagic fever (DHF) data to simple vector–host and SIR models using Bayesian Markov chain Monte Carlo estimation. The parameter estimates obtained for both models were consistent with previous studies. Most importantly, model selection found that the SIR model was substantially better than the vector–host model for the DHF data from Thailand. Therefore, explicitly incorporating the mosquito population may not be necessary in modeling dengue transmission for some populations.

A 31-year-old Hmong (Thai hilltribe) multiparous (G5P2) female with dengue hemorrhagic fever delivered a low birth weight male infant at 34 weeks estimated gestational age. The mother had fever for a total of 6 days, along with hepatomegaly, hepatic dysfunction and thrombocytopenia. Serology showed acute secondary dengue infection. She had no serious complications. The infant (birth weight 1,850 grams) developed a fever 140 hours postpartum of 37.8 degrees C for one day, then developed drowsiness, poor feeding and apnea. Hepatomegaly, thrombocytopenia, hepatic dysfunction and moderate coagulopathy were detected, with consequential shock and anemia due to gastrointestinal and pulmonary hemorrhage. Vigorous treatment with mechanical ventilation, packed red cells (PRC), fresh frozen plasma (FFP) and platelet concentrate transfusions were given and the child recovered successfully and commenced breast-feeding. At six months of age the child's growth and development were normal except for an impaired hearing screening test.

Immunological laboratory tests play an important role in establishing the depth of extent of this or that infectious disease. Scheduled immunological monitoring (serological screening) is made to find out whether there are antibodies (Abs) against the causative agents of individual feral herd infections. The immunological examination is aimed at detecting Abs against the pathogens of infectious diseases of bacterial (Ixodes tick-borne borrelioses, tularemia, leptospiroses, human granulocytic anaplasmosis), viral (hemorrhagic fever with renal syndrome, tick-borne viral encephalitis, West Nile fever), and rickettsial (Q-fever) etiologies. The performed serological screening could yield data on the practically widespread of hemorrhagic fever with renal syndrome in the Ulyanovsk Region and show high rates of Abs to Ixodes tick-borne borrelioses (5.75), coxiellosis (3.7%), and human granulocytic anaplasmosis (4.3%).

Dengue virus is distributed in tropical and subtropical regions and transmitted by mosquitoes of the genus Aedes. In September 2010 two cases of indigenous dengue fever were diagnosed in metropolitan France for the first time and next DENV infection was diagnosed in a German traveler returning from a trip to Croatia. The Aedes albopictus mosquitoes were found in several European countries (for example in greenhouses in Netherlands). The indigenous DENV infections in Europe are rare diseases, probably acquired after bites of infected mosquitoes imported by airplanes from endemic areas. Nonspecific symptoms including: fever (up to 39 degrees C), chills, arthralagia, headache, myalgia and abnormalities in laboratory tests such as: thrombocytopaenia, leukopaenia and liver tests cause problems with differential diagnosis ofhematologic and hepatologic syndromes. The most serious complications are associated with dengue shock syndrome with mortality rate of 50%.

The epidemiology of dengue is characterised by irregular epidemic outbreaks and desynchronised dynamics of its four co-circulating virus serotypes. Whilst infection by one serotype appears to convey life-long protection to homologous infection, it is believed to be a risk factor for severe disease manifestations upon secondary, heterologous infection due to the phenomenon of Antibody-Dependent Enhancement (ADE). Subsequent clinical infections are rarely reported and, since the majority of dengue infections are generally asymptomatic, it is not clear if and to what degree tertiary or quaternary infections contribute to dengue epidemiology. Here we investigate the effect of third and subsequent infections on the transmission dynamics of dengue and show that although the qualitative patterns are largely equivalent, the system more readily exhibits the desynchronised serotype oscillations and multi-annual epidemic outbreaks upon their inclusion. More importantly, permitting third and fourth infections significantly increases the force of infection without resorting to high basic reproductive numbers. Realistic age-prevalent patterns and seroconversion rates are therefore easier reconciled with a low value of dengue's transmission potential if allowing for more than two infections; this should have important consequences for dengue control and intervention measures.

Objective: This study aimed to examine whether spatial-temporal patterns of dengue can be used to identify areas at risk of dengue hemorrhagic fever (DHF)., Methods: Three indices - probability of case-occurrence, mean duration per wave, and transmission intensity - were used to differentiate eight local spatial-temporal patterns of dengue during the 2002 epidemic in Kaohsiung, Taiwan. DHF densities (DHF cases/km(2) per 100 dengue cases) in each spatial-temporal typed area were compared., Results: Areas with three high indices correlated with the highest DHF density: (1) high transmission intensity only; (2) long duration of wave only, and (3) high transmission intensity plus long duration of wave. However, cumulative incidences of dengue cases were not correlated with DHF densities., Conclusion: Three spatial-temporal indices of dengue could provide useful information to identify areas at high risk of DHF.

Dengue and dengue hemorrhagic fever are increasing public health problems with an estimated 50-100 million new infections each year. Aedes aegypti is the major vector of dengue viruses in its range and control of this mosquito would reduce significantly human morbidity and mortality. Present mosquito control methods are not sufficiently effective and new approaches are needed urgently. A "sterile-male-release" strategy based on the release of mosquitoes carrying a conditional dominant lethal gene is an attractive new control methodology. Transgenic strains of Aedes aegypti were engineered to have a repressible female-specific flightless phenotype using either two separate transgenes or a single transgene, based on the use of a female-specific indirect flight muscle promoter from the Aedes aegypti Actin-4 gene. These strains eliminate the need for sterilization by irradiation, permit male-only release ("genetic sexing"), and enable the release of eggs instead of adults. Furthermore, these strains are expected to facilitate area-wide control or elimination of dengue if adopted as part of an integrated pest management strategy.

Dengue (Df) and Chikungunya fever (Cf) arbovirosis are booming in the world, because of the plasticity of their pathogens, mutant RNA viruses making the acquisition of sustainable herd immunity and vaccination difficult in humans, and the plasticity of their vectors, the female mosquitoes of the genus Aedes (Stegomya), capable of adapting to different environments. This review summarizes the viral life cycle and epidemiology of these arboviruses, pathogenesis and pediatric aspects of their clinical forms and the basic principles of their treatment and prevention., (Copyright 2009 Elsevier Masson SAS. All rights reserved.)

The vector for dengue fever and chikungunya, Aedes albopictus, was recently identified in Southeastern France, although the usual vector for dengue fever is Aedes aegypti, raising the possibility of cases occurring among the local population via viraemic individuals returning from endemic areas. Dengue fever is usually transmitted by Aedes aegypti. It is due to an arbovirus-flavivirus of which four different serotypes are known: Den 1 to 4. Each serotype is responsible for specific prolonged immunity but no cross-reactivity exists between serotypes. Clinically, the onset is abrupt with frontal headache, retro-orbital pain, myalgia, joint pain, prostration and, in many cases, a macular rash usually sparing the face and extremities. Haemorrhagic signs may occur, such as petechiae, purpura, epistaxis or bleeding gingivae. Two severe forms of dengue fever, particularly among children below 3 years of age, include dengue haemorrhagic fever (DHF) and DHF with shock (dengue shock syndrome). If a case is suspected in metropolitan France, the diagnosis should be systematically confirmed by positive specific IgM, RT-PCR or viral isolation. Treatment of dengue fever, whether in its uncomplicated form or with hemorrhagic manifestations or shock, remains symptomatic. There is no specific anti-viral treatment. A case should be notified to allow French health authorities to take the appropriate measures for vector control.

Background & Objective: Dengue haemorrhagic fever (DHF) is the major cause of sustained morbidity/ mortality among human cases of dengue in dengue endemic areas of Rajasthan. Screening of mosquitoes collected from disease endemic settings and typing the virus could provide significant epidemiological information for prospective risk of DHF. We therefore carried out a study on different dengue virus types as occurring in field collected Aedes aegypti mosquitoes from four dengue endemic districts of Rajasthan, India., Methods: Adult Ae. aegypti were collected from the human dwellings of urban, peri-urban and rural settings of four dengue endemic districts of Rajasthan, India. The field collected adults were fed on 4 per cent glucose solution and kept in the laboratory for 3-4 days. The adult field collected Ae. aegypti, were subjected to indirect fluorescence antibody test (IFAT) following standard procedure. Commercially acquired monoclonal antibodies against DEN types 1, 2, 3 and 4 were used. The remnants of IFA test subjected mosquitoes were made into viral suspension which was inoculated into the cell culture medium and mouse brain to confirm the presence of virus as shown by IFA test., Results: Of the 498 adult Ae. aegypti tested, 78 (15.6%) were positive by IFA test. Among urban areas, desert area (Jodhpur) showed highest (21.6%) mosquito infectivity followed by 7.1 per cent in forest and river area (Kota) and least (3.2%) in semi-arid area (Jaipur). Among rural settings also, desert area showed maximum (25.0%) natural infection in mosquitoes followed by rural setting-1 of semi-arid area (24.1%). Among urban setting of desert area, all the four dengue types viz., DEN-1, 2, 3 and 4 were detected. In semi-arid area, urban settings showed presence of DEN-3, whereas among rural settings, rural-1 showed all the four DEN types, rural-2 showed DEN-1 and DEN-3, rural-4 showed DEN-3 and DEN-4, and rural-3 showed no mosquito infections. In forest and river area, among urban settings only, three DEN types, 1, 2 and 4 were observed., Interpretation & Conclusion: In desert and semi-arid areas of Rajasthan, where people possess tendency of over- and sustained storage of domestic water, present observations on occurrence of all four dengue virus types may have important bearing on the epidemiology of DHF in the area.

Dengue is currently the most common arboviral infection worldwide. Due to global climate change and other factors, the vector of the virus - the Aedes mosquito - has spread considerably over the past decades. Dengue is endemic in almost all tropical and sub-tropical regions of the world; meaning that approximately 40% of the world population is at risk of acquiring a dengue infection. The clinical features of dengue vary from a non-specific febrile illness (dengue fever) to at times fatal serious conditions such as dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS). Considering the limited possibilities of prevention it is anticipated that the incidence of dengue will increase in the future. It is expected that health-care providers in non-endemic regions will encounter dengue-infected patients with increasing frequency in their practices.

Objective: Clinicians in resource-poor countries need to identify patients with dengue using readily-available data. The objective of this systematic review was to identify clinical and laboratory features that differentiate dengue fever (DF) and/or dengue haemorrhagic fever (DHF) from other febrile illnesses (OFI) in dengue-endemic populations., Method: Systematic review of the literature from 1990 to 30 October 2007 including English publications comparing dengue and OFI., Results: Among 49 studies reviewed, 34 did not meet our criteria for inclusion. Of the 15 studies included, 10 were prospective cohort studies and five were case-control studies. Seven studies assessed all ages, four assessed children only, and four assessed adults only. Patients with dengue had significantly lower platelet, white blood cell (WBC) and neutrophil counts, and a higher frequency of petechiae than OFI patients. Higher frequencies of myalgia, rash, haemorrhagic signs, lethargy/prostration, and arthralgia/joint pain and higher haematocrits were reported in adult patients with dengue but not in children. Most multivariable models included platelet count, WBC, rash, and signs of liver damage; however, none had high statistical validity and none considered changes in clinical features over the course of illness., Conclusions: Several individual clinical and laboratory variables distinguish dengue from OFI; however, some variables may be dependent on age. No published multivariable model has been validated. Study design, populations, diagnostic criteria, and data collection methods differed widely across studies, and the majority of studies did not identify specific aetiologies of OFIs. More prospective studies are needed to construct a valid and generalizable algorithm to guide the differential diagnosis of dengue in endemic countries.

In this paper, we discuss a two-age-classes dengue transmission model with vaccination. The reason to divide the human population into two age classes is for practical purpose, as vaccination is usually concentrated in one age class. We assume that a constant rate of individuals in the child-class is vaccinated. We analyze a threshold number which is equivalent to the basic reproduction number. If there is an undeliberate vaccination to infectious children, which worsens their condition as the time span of being infectious increases, then paradoxically, vaccination can be counter productive. The paradox, stating that vaccination makes the basic reproduction number even bigger, can occur if the worsening effect is greater than a certain threshold, a function of the human demographic and epidemiological parameters, which is independent of the level of vaccination. However, if the worsening effect is to increase virulence so that one will develop symptoms, then the vaccination is always productive. In both situations, screening should take place before vaccination. In general, the presence of class division has obscured the known rule of thumb for vaccination.

Dengue is the most important mosquito borne virus infection in the tropics. Based on the effects of global warming, it is expected that dengue epidemic areas will further expand in the next decades unless effective and affordable vaccines are made available soon. At the moment, several vaccine developers have utilized live-attenuated live tetravalent vaccines and two of them have already completed phase two trials. However, the risk of antibody-dependent enhancement infection is not well elucidated and thus further and careful evaluation of the safety on proposed candidate vaccines are essential. At the moment, Bill and Melinda Gates Foundation strongly support the vaccine development through the Pediatric Dengue Vaccine Initiative.

A statistical model for predicting monthly Dengue Hemorrhagic Fever (DHF) cases from the city of Makassar is developed and tested. The model uses past and present DHF cases, climate and meteorological observations as inputs. These inputs are selected using a stepwise regression method to predict future DHF cases. The model is tested independently and its skill assessed using two skill measures. Using the selected variables as inputs, the model is capable of predicting a moderately-severe epidemic at lead times of up to six months. The most important input variable in the prediction is the present number of DHF cases followed by the relative humidity three to four months previously. A prediction 1-6 months in advance is sufficient to initiate various activities to combat DHF epidemic. The model is suitable for warning and easily becomes an operational tool due to its simplicity in data requirement and computational effort.

Background: Dengue is the most prevalent mosquito-borne virus, and potentially fatal dengue hemorrhagic fever (DHF) occurs mainly in secondary infections. It recently was hypothesized that, due to the presence of cross-immunity, the relationship between the incidence of DHF and transmission intensity may be negative at areas of intense transmission. We tested this hypothesis empirically, using vector abundance as a surrogate of transmission intensity., Methodology/principal Findings: House Index (HI), which is defined as the percentage of households infested with vector larvae/pupae, was obtained from surveys conducted on one million houses in Thailand, between 2002 and 2004. First, the utility of HI as a surrogate of transmission intensity was confirmed because HI was correlated negatively with mean age of DHF in the population. Next, the relationship between DHF incidence and HI was investigated. DHF incidence increased only up to an HI of about 30, but declined thereafter. Reduction of HI from the currently maximal level to 30 would increase the incidence by more than 40%. Simulations, which implemented a recently proposed model for cross-immunity, generated results that resembled actual epidemiological data. It was predicted that cross-immunity generates a wide variation in incidence, thereby obscuring the relationship between incidence and transmission intensity. The relationship would become obvious only if data collected over a long duration (e.g., >10 years) was averaged., Conclusion: The negative relationship between DHF incidence and dengue transmission intensity implies that in regions of intense transmission, insufficient reduction of vector abundance may increase long-term DHF incidence. Further studies of a duration much longer than the present study, are warranted.

We report epidemiology of dengue infection as revealed through a hospital based surveillance for dengue infection over a 3 year period in Lucknow, U.P., India. In 2003-2005, children with acute febrile encephalopathy (AFE) and in 2005-2006, children with acute undifferentiated febrile illness (AUFI) were enrolled. IgM antibodies to dengue were tested by ELISA in acute serum. A total of 118/563 (20.9%) patients tested positive for dengue antibodies. Dengue transmission occurred round the year in the Lucknow region with peak in postmonsoon season and occurred equally in rural and urban areas. All the surrounding districts were affected, with no distinct high prevalence areas.

Since the reinfestation of South American countries by Ae. aegypti, dengue fever (DF) and dengue hemorrhagic fever (DHF) have become a major public health concern. The aim of this paper was to review the information related with Aedes vectors and dengue in Argentina since the reintroduction of Ae. aegypti in 1986. The geographic distribution of Ae. albopictus is restricted to the Northeast, and that of Ae. aegypti has expanded towards the South and the West in comparison with the records during the eradication campaign in the 1960s. Since 1998, 4,718 DF cases have been reported concentrated in the provinces of Salta, Formosa, Misiones, Jujuy and Corrientes. Despite the circulation of three dengue virus serotypes (DENV-1, -2 and -3) in the North of the country, DHF has not occurred until the present. The information published over the last two decades regarding mosquito abundance, temporal variations, habitat characteristics, competition, and chemical and biological control, was reviewed. Considering the available information, issues pending in Argentina are discussed. The presence of three DENV, the potential spread of Ae. albopictus, and the predicted climate change suggest that dengue situation will get worse in the region. Research efforts should be increased in the Northern provinces, where DHF is currently an actual risk.

Dengue is a spectrum of disease caused by four serotypes of the most prevalent arthropod-borne virus affecting humans today, and its incidence has increased dramatically in the past 50 years. Due in part to population growth and uncontrolled urbanization in tropical and subtropical countries, breeding sites for the mosquitoes that transmit dengue virus have proliferated, and successful vector control has proven problematic. Dengue viruses have evolved rapidly as they have spread worldwide, and genotypes associated with increased virulence have expanded from South and Southeast Asia into the Pacific and the Americas. This review explores the human, mosquito, and viral factors that contribute to the global spread and persistence of dengue, as well as the interaction between the three spheres, in the context of ecological and climate changes. What is known, as well as gaps in knowledge, is emphasized in light of future prospects for control and prevention of this pandemic disease.

A serological survey of primary school children from six schools in Chachoengsao Province, Thailand, was performed at the end of the peak of dengue transmission. GIS analysis of sero-positive cases was carried out to determine transmission foci. Vector control implementation was conducted in the foci and also within 100 meters around the foci in the treated areas by community participation in collaboration with the local government. Vector control strategies included source reduction together with the use of screen covers, a combination of Bacillus thuringiensis subsp. israelensis and Mesocyclops thermocyclopoides, and lethal ovitraps. Implementation of vector control strategies in the foci was continued until the end of the rainy season. Vector control effectiveness was monitored using entomological, serological, and clinical parameters. Results showed a significant reduction of dengue vectors as well as a decrease in sero-positive children and clinical cases in treated areas when compared with untreated areas.

Dengue fever and dengue haemorrhagic fever (DF/DHF) have become a serious public health problem in many parts of India in recent years. Several vertical national programmes for communicable diseases, which include vector-borne diseases such as malaria and filariasis have been in operation for over five decades in India. The remarkable increase in dengue fever and DHF related deaths during the last decade has necessitated an effective surveillance system to detect the cases and adopt appropriate control measures against dengue vectors. Although the existence of all the four serotypes of dengue virus was proved as early as in 1960s, it was only after 1990, several outbreaks of DF/DHF were reported in Tamil Nadu. Further, dengue, once considered as urban problem has now penetrated into rural areas also, due to various changes in the environment. The geographic spread, increase in number of cases, reporting system, laboratory diagnosis, monitoring of vector density and investigation of outbreaks in Tamil Nadu during the last decade are comprehensively documented and discussed here to further strengthen the surveillance network to prevent possible major outbreaks of DF/DHF.

Dengue virus transmission has increased dramatically in the past 2 decades, making this virus one of the most important mosquito-borne human pathogens. The emergence of dengue hemorrhagic fever in most tropical countries has made its control a public health priority, but no vaccines or treatments exist. Little is understood about dengue virus pathogenesis, because no other animals develop symptoms of disease, and research, therefore, has been limited to studies involving patients. Although epidemiologic and evolutionary studies have pointed to host and viral factors in determining disease outcome, only recently developed models could prove the importance of viral genotypes in causing severe epidemics. The influence of host immune status and mosquito vectorial capacity are also being tested in mathematical models to determine virus population dynamics. Therefore, new technologies are allowing us to better understand how specific virus variants cause more disease than others, and these virus variants should be targeted for detection, control, and treatment.