It has been demonstrated that DENV infection induced the expression of cathepsin-B, a putative cystatin, and a hypothetical ankyrin repeat-containing protein genes [38]

It has been demonstrated that DENV infection induced the expression of cathepsin-B, a putative cystatin, and a hypothetical ankyrin repeat-containing protein genes [38]. the development of animal models will enormously help improving the therapeutic interventions and potentially contribute to finding new preventive measures intended for population at risk. Keywords: Dengue, Aedes Aegypti, Dengue hemorrhagic fever, Hemorrhagic shock syndrome, Genetic susceptibility, Vaccine development == Background == Dengue fever is a major cause of illness and death worldwide. The disease is caused by dengue virus which gets transmitted to humans by the bites of infected mosquitoes, Aedes (Ae. ) aegyptiandAe. albopictus[1]. The disease represents a global health issue as it is endemic in around 100 countries, most of which are in tropical and sub-tropical areas. Over the last decades, the incidence rate and the geographic distribution of dengue have rapidly increased (almost 30-fold). Data from the World Health Organization (WHO) estimates up to 100 million cases of dengue fever each year [2]. However , a recent published work by Bhatt et al. (2013) suggested that the burden of dengue is far more than the WHO estimation and Cetrimonium Bromide(CTAB) indicated that 390 million infections of dengue computer virus could have happened every year [3]. Changes in dengue epidemiology and the increase in incidence rates (with and without co-morbidities) have led the WHO to propose a new dengue classification system according to disease severity (Fig. 1) [2]. == Fig. 1 . == WHO dengue case classification (Adopted from; Dengue Guidelines intended for diagnosis, treatment, prevention and control, New edn. Geneva: WHO; 2009) == Etiology and mode of transmission == Dengue fever is caused by infection with dengue virus (DENV). The DENV is a vector-borne virus transmitted to humans primarily by bites from two mosquito species, Ae. aegyptiorAe. albopictus. DENV is a single positive-stranded RNA computer virus belonging to Flavivirus genus of theFlaviviridaefamily and has 4 major serotypes (DENV 14) that are antigenically distinct from each other. Each DENV serotype is phylogenetically distinct suggesting that each serotype could be considered a separate computer virus [4]. Three dengue serotypes out of four (DENV 13) have been found in Middle Eastern countries including Saudi Arabia and Yemen. Interestingly, DENV-1 strain isolated in Cetrimonium Bromide(CTAB) Saudi Arabia exhibited a high genetic similarity with DENV-1 strain isolated from Asian population, suggesting a widespread of the Asian genotype, probably through Asian pilgrims [5, 6]. A recently published article has unveiled a new serotype (DENV-5), to be added to the existing ones [7]. This discovery is still controversial and little-known enough to conclude how the 5thdengue serotype might add to the burden associated with dengue infection. Mosquitoes transmit the computer virus by feeding on blood of infected persons. At first, the computer virus infects and replicates in S1PR2 the mid-gut epithelium of the mosquito and then spreads to other organs until it reaches the salivary glands after 1014 days where it can be inoculated to another person during subsequent blood meal. Vertical transmission of DENV in mosquitoes, i. e. from mosquito to larvae has been reported by a number of research groups. In India, Angel & Joshi (2008) reported the detection of dengue virus by indirect fluorescence antibody test (IFAT) in laboratory reared mosquitoes originating from larvae collected from urban and rural areas [8]. A similar study was conducted in Brazil by Martins et al. (2012) and confirmed the isolation of DENV-type 3 inAe. albopictuslarvae and DENV-type 2 inAe. aegyptilarvae [9]. Similar findings were also reported in Mexico [10] and Indonesia [11]. On the other hand, mother-to-infant transmission of dengue virus via cord blood or breast milk remains controversial [1214]. == Clinical manifestations == Based on the results from several studies, the WHO has launched a new dengue classification. This classification divides dengue cases into a) cases with/without warning signs and b) severe dengue cases [2]. However , it is important to note that numerous research groups have debated the rational of this classification as it does not fit their unique local settings. The criteria for dengue case classification are presented in Fig. 1 . Clinically, dengue infection has a broad spectrum of features. The vast majority of cases are asymptomatic and passes unnoticed. Typically, the symptoms start to be prominent after an incubation period of 310 days [15]. The severity of the clinical manifestations varies from mild Cetrimonium Bromide(CTAB) symptoms to severe life threatening symptoms in the case of dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) [16]. Predicting the progression of the mild signs to a severe DHF/DSS remains a challenge due to non-specificity of clinical presentation and the incomplete understanding of pathophysiology of the disease and its Cetrimonium Bromide(CTAB) underlying molecular mechanisms. == Dengue with warning signs == The early signs of the disease are non-specific. According to the WHO classification (2009), DF is characterized by febrile episode (40 C for 27 days).