Dengue fever and Dengue Hemorrhagic fever: A review of history, transmission, treatment and prevention
Available from: Matheus Ismerim
- "It is considered a major public health concern because it is largely dispersed in urban areas (Porto et al., 2008). Given that 50 to 80 million people are infected with dengue anually in over 100 countries, vector control is extremely important and consists of eliminating breeding sites and applying insecticides (Lingon, 2005; Mendonça et al., 2009). However, synthetic insecticides have been observed to have low efficiency due to resistance of insect populations (Barreto, 2005). "
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ABSTRACT: Dengue fever and schistosomiasis are major public health issues for which vector control using larvicide and molluscicide substances present in plants provides a promising strategy. This study evaluated the potential toxicity of the extract of hydroethanol Schinopsis brasiliensis Engl., Anacardiaceae, stem bark and its chloroform, hexane, ethyl acetate, and hydromethanol fractions against Artemia salina and Aedes Aegypti larvae and snails Biomphalaria glabrata. All of the assays were performed in triplicate and the mean mortality rates were used to determine the LC50 and LC90 values using the probit method. The hydroethanol hydromethanol extract and fraction were free of toxicity towards A. salina (LC50 > 1000 μg/ml), while chloroform fraction was moderately toxic (LC50 313 μg/ml); ethyl acetate and hexane fractions displayed low toxicity, with LC50 557 and 582 μg/ml, respectively. Chloroform, hexane, and ethyl acetate fractions showed larvicidal potential towards A. aegypti (LC50 values of 345, 527 and 583 μg/ml, respectively), while chloroform and ethyl acetate fractions were highly toxic to B. glabrata (LC90 values of 68 and 73 μg/ml, respectively). Based on these findings, ethyl acetate, chloroform, and hexane fractions should be further investigated for their potential use against the vectors of dengue and schistosomiasis.
Available from: Jose Maria Barbosa Filho
- "Dengue is an infectious disease caused by an arbovirus transmitted to humans by the bite of female mosquitoes of the genus Aedes. Among many vectors, Aedes aegypti L. (Diptera: Culicidae) is the one of utmost epidemiological importance (Ligon, 2005; Coelho et al., 2009). Over the past 60 years the incidence, distribution , and clinical severity of dengue have increased dramatically; resulting in the most important viral disease transmitted by arthropod vectors in terms of mortality and morbidity (Rigau-Pérez et al., 1998; Rosen, 1999). "
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ABSTRACT: The aim of this study was to evaluate the larvicidal activity of Mentha x villosa essential oil (MVEO) and its major constituent, rotundifolone, against larvae of Aedes aegypti. Additionally, a set of 15 analogues of the rotundifolone were evaluated to identify the molecular characteristics which contribute to the larvicidal effect. The results from the present study showed that the MVEO exhibited outstanding toxic effects against Ae. aegypti larvae (LC50=45.0ppm). Rotundifolone exhibited reasonable larvicidal activity (LC50=62.5ppm). With respect to comparative study of rotundifolone and its analogues, all tested compounds were less potent than rotundifolone, except (-)-limonene. In general, replacement of C-C double bonds by epoxides groups decreases the larvicidal potency. The presence of α,β-unsaturated carbonyls contributes to the larvicidal toxicity. The addition of hydroxyl groups in the chemical structure resulted in less potent compounds. Furthermore, the enantioselectivity seems to play an important role for the larvicidal toxicity.
Available from: Tzong-shiann Ho
- "Early recognition of dengue is challenging because the initial symptoms are often non-specific, viremia may be below detectable levels and serological tests confirm dengue late in the course of illness
. Prompt diagnosis during the febrile stage is essential for adjusting appropriate management
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ABSTRACT: Early diagnosis of dengue virus infection during the febrile stage is essential for adjusting appropriate management. This study is to identify the predictive markers of clinical and laboratory findings in the acute stage of dengue infection during a major outbreak of dengue virus type 1 that occurred in southern Taiwan during 2007. A retrospective, hospital-based study was conducted at a university hospital in southern Taiwan from January to December, 2007. Patient who was reported for clinically suspected dengue infection was enrolled. Laboratory-positive dengue cases are confirmed by enzyme-linked immunosorbent assay of specific dengue IgM, fourfold increase of dengue-specific IgG titers in convalescent serum, or by reverse transcription-polymerase chain reaction (RT-PCR) of dengue virus.
The suspected dengue cases consist of 100 children (<= 18 years) and 481 adults. Among the 581 patients, 67 (67%) children and 309 (64.2%) adults were laboratory-confirmed. Patients who had laboratory indeterminate were excluded. Most cases were uncomplicated and 3.8% of children and 2.9% of adults developed dengue hemorrhagic fever or dengue shock syndrome (DHF/DSS). The overall mortality rate in those with DHF/DSS was 7.1%, and the average duration of hospitalization was 20 days. The most common symptoms/signs at admission were myalgia (46.8%), petechiae (36.9%) and nausea /vomiting (33.5%). The most notable laboratory findings included leukopenia (2966 +/- 1896/cmm), thrombocytopenia (102 +/- 45 x 103/cmm), prolonged activated partial thromboplastin time (aPTT) (45 +/- 10 s), and elevated serum levels of aminotransferase (AST, 166 +/- 208 U/L; ALT, 82 +/- 103 U/L) and low C - reactive protein (CRP) (6 +/- 11 mg/L). Based on the clinical features for predicting laboratory-confirmed dengue infection, the sensitivities of typical rash, myalgia, and positive tourniquet test are 59.2%, 46.8%, and 34.2%, while the specificities for above features are 75.4%, 53.5% and 100%, respectively. The positive predictive value (PPV) for combination of leukopenia, thrombocytopenia (< 150 x 103/cmm), elevated aminotransferase (AST/ALT > 1.5) and low CRP (< 20 mg/L) is 89.5%, while the negative predictive value is 37.4%. Furthermore, the PPV of the combination was increased to 93.1% by adding prolonged aPTT (>38 secs).
Leukopenia, thrombocytopenia, elevated aminotransferases, low CRP and prolonged aPTT, were useful predictive markers for early diagnosis of dengue infection during a large outbreak in southern Taiwan.
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