SciCombinator

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Concept: Dengue

198

Dengue poses a substantial economic and disease burden in Southeast Asia (SEA). Quantifying this burden is critical to set policy priorities and disease-control strategies.

Concepts: Southeast Asia, Dengue

168

The occurrence of dengue haemorrhagic fever (DHF) is thought to result from a complex interplay between the virus, host genetics and host immune factors. Existing published data are not consistent, in part related to relatively small sample sizes. We set out to determine possible associations between dengue virus (DEN-V) NS3 specific T cells and cytokine and chemokine levels and the pathogenesis of severe disease in a large cohort of individuals with DHF.

Concepts: Immune system, DNA, Sample size, Virus, Ribavirin, Fever, Dengue fever, Dengue

105

Dengue is a mosquito-transmitted virus infection that causes epidemics of febrile illness and hemorrhagic fever across the tropics and subtropics worldwide. Annual epidemics are commonly observed, but there is substantial spatiotemporal heterogeneity in intensity. A better understanding of this heterogeneity in dengue transmission could lead to improved epidemic prediction and disease control. Time series decomposition methods enable the isolation and study of temporal epidemic dynamics with a specific periodicity (e.g., annual cycles related to climatic drivers and multiannual cycles caused by dynamics in population immunity). We collected and analyzed up to 18 y of monthly dengue surveillance reports on a total of 3.5 million reported dengue cases from 273 provinces in eight countries in Southeast Asia, covering ∼10(7) km(2). We detected strong patterns of synchronous dengue transmission across the entire region, most markedly during a period of high incidence in 1997-1998, which was followed by a period of extremely low incidence in 2001-2002. This synchrony in dengue incidence coincided with elevated temperatures throughout the region in 1997-1998 and the strongest El Niño episode of the century. Multiannual dengue cycles (2-5 y) were highly coherent with the Oceanic Niño Index, and synchrony of these cycles increased with temperature. We also detected localized traveling waves of multiannual dengue epidemic cycles in Thailand, Laos, and the Philippines that were dependent on temperature. This study reveals forcing mechanisms that drive synchronization of dengue epidemics on a continental scale across Southeast Asia.

Concepts: Epidemiology, Infectious disease, Southeast Asia, Philippines, Fever, Dengue fever, Dengue, Viral hemorrhagic fever

42

Zika virus co-circulates with dengue in tropical and sub-tropical regions. Cases of co-infection by dengue and Zika have been reported, the implication of this co-infection for an integrated intervention program for controlling both dengue and Zika must be addressed urgently. Here, we formulate a mathematical model to describe the transmission dynamics of co-infection of dengue and Zika with particular focus on the effects of Zika outbreak by vaccination against dengue among human hosts. Our analysis determines specific conditions under which vaccination against dengue can significantly increase the Zika outbreak peak, and speed up the Zika outbreak peak timing. Our results call for further study about the co-infection to direct an integrated control to balance the benefits for dengue control and the damages of Zika outbreak.

Concepts: Mathematics, Tropics, Tropic of Cancer, Control, Mathematical model, Dengue, Zika fever

33

Chikungunya and dengue infections are spatio-temporally related. The current review aims to determine the geographic limits of chikungunya, dengue and the principal mosquito vectors for both viruses and to synthesise current epidemiological understanding of their co-distribution.

Concepts: Microbiology, Aedes aegypti, The Current, Mosquito control, Dengue

30

Background. Dengue virus (DENV) causes hundreds of millions of infections annually. Four dengue serotypes exist and previous infection with one serotype increases the likelihood of severe disease with a second, heterotypic DENV infection.Methods. In a randomized, placebo-controlled study, the safety and immunogenicity of four different admixtures of a live attenuated tetravalent (LATV) dengue vaccine were evaluated in 113 flavivirus-naïve adults. Serum neutralizing antibody levels to all four dengue viruses were measured on days 0, 28, 42, and 180. Clinicaltrials.gov: NCT01072786Results. A single dose of each LATV admixture induced a trivalent or better neutralizing antibody response in 75% to 90% of vaccinees. There was no significant difference in the incidence of adverse events between vaccinees and placebo-recipients other than rash. A trivalent or better response correlated with rash and with non-Black race (p<0.0001). Black race was significantly associated with a reduced incidence of vaccine viremia.Conclusions. TV003 induced a trivalent or greater antibody response in 90% of flavivirus-naïve vaccinees and is a promising candidate for the prevention of dengue. Race was identified as a factor influencing the infectivity of the LATV viruses, reflecting observations of the effect of race on disease severity in natural dengue infection.

Concepts: Immune system, Clinical trial, Virus, Infection, Immunology, Dengue fever, Measles, Dengue

28

Zika virus is a member of the flavivirus genus that had not been associated with severe disease in humans until the recent outbreaks, when it was linked to microcephaly in newborns in Brazil and to Guillain-Barré syndrome in adults in French Polynesia. Zika virus is related to dengue virus, and we report here that a category of antibodies isolated from dengue patients and targeting a conformational epitope potently neutralize Zika virus. The crystal structure of two of these antibodies in complex with the envelope protein of Zika virus reveals the details of a conserved epitope, which is also the site of interaction of the envelope protein dimer with the precursor prM protein during virus maturation. Comparison of the Zika and dengue virus immunocomplexes provides a lead for rational, epitope-focused design of a universal vaccine capable of eliciting potent cross-neutralizing antibodies to protect against Zika and dengue viruses simultaneously.

Concepts: Immune system, Antibody, Protein, Virus, Antigen, Epitope, Viruses, Dengue

28

Dengue viruses (DENV) infect 50 to 100 million people worldwide per year, of which 500,000 develop severe life-threatening disease. This mosquito-borne illness is endemic in most tropical and subtropical countries and has spread significantly over the last decade. While there are several promising vaccine candidates in clinical trials, there are currently no approved vaccines or therapeutics available for treatment of dengue infection. Here, we describe a novel small-molecule compound, ST-148, that is a potent inhibitor of all four serotypes of DENV in vitro. ST-148 significantly reduced viremia and viral load in vital organs and tended to lower cytokine levels in the plasma in a nonlethal model of DENV infection in AG129 mice. Compound resistance mapped to the DENV capsid © gene, and a direct interaction of ST-148 with C protein is suggested by alterations of the intrinsic fluorescence of the protein in the presence of compound. Thus, ST-148 appears to interact with the DENV C protein and inhibits a distinct step(s) of the viral replication cycle.

Concepts: Protein, Microbiology, Virus, Malaria, Virology, Fever, Measles, Dengue

27

Dengue fever is re-emerging as a major scourge in south-east Asian countries affecting about 50-100 million people and causing about 25,000 mortality annually. India as a whole is under the risk of infection of this disease. We genetically characterized viruses causing Dengue infections in Kerala, one of the worst affected states of the Country during the disease outbreaks 2008-2010. All the 4 serotypes of the virus: DENV-1, DENV-2, DENV-3 & DENV-4 were found to be prevalent in the state. The genotypes recognized for these were III, IV, III and I respectively. The phylogenetic analysis evidenced that the re-emergence of serotype DENV-4 reported in Maharashtra and Andhra Pradesh recently, is spreading to different regions of the Country. The circulation of all the 4 Dengue serotypes in Kerala, may lead to increase in the prevalence of more severe complications of this emerging disease, such as Dengue Hemorrhagic fever and Dengue shock syndromes.

Concepts: Disease, Virus, Infection, Ribavirin, Fever, Dengue fever, Dengue, States and territories of India

24

During a dengue epidemic in northern Mexico, enhanced surveillance identified 53 laboratory-positive cases in southern Texas; 26 (49%) patients acquired the infection locally, and 29 (55%) were hospitalized. Of 83 patient specimens that were initially IgM negative according to ELISA performed at a commercial laboratory, 14 (17%) were dengue virus positive by real-time reverse transcription PCR performed at the Centers for Disease Control and Prevention. Dengue virus types 1 and 3 were identified, and molecular phylogenetic analysis demonstrated close identity with viruses that had recently circulated in Mexico and Central America. Of 51 household members of 22 dengue case-patients who participated in household investigations, 6 (12%) had been recently infected with a dengue virus and reported no recent travel, suggesting intrahousehold transmission. One household member reported having a recent illness consistent with dengue. This outbreak reinforces emergence of dengue in southern Texas, particularly when incidence is high in northern Mexico.

Concepts: Epidemiology, Molecular biology, Virus, Infection, Mexico, Americas, Central America, Dengue