Understanding the Dengue Virus : Symptoms, Transmission, and Prevention.

The dengue virus is a mosquito-borne virus that belongs to the Flavivirida family. It is primarily transmitted to humans through the bites of infected Aedes mosquitoes, particularly Aedes aegypti and Aedes albopictus. The virus has four distinct serotypes (DENV-1, DENV-2, DENV-3, and DENV-4), and infection with one serotype provides lifelong immunity to that serotype but not to the others. Dengue virus infection can cause a wide range of symptoms, from mild fever to severe conditions like dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), which can be life-threatening. There is no specific antiviral treatment for dengue, and prevention focuses on controlling mosquito populations and preventing bites.

1. Dengue Viruses S. Nahidha Begum II. M.Sc Microbiology Sacred Heart College

2. Dengue Viruses Introduction Dengue is a viral infection transmitted by mosquitoes. There are four serotypes of the dengue virus: DEN-1, DEN-2, DEN-3, and DEN-4. The illness caused by dengue ranges from mild fever to severe, life-threatening conditions.

3. Properties of Dengue Virus Arbovirus Belongs to the family Flaviviridae and genus Flavivirus Transmitted by arthropods, primarily mosquitoes. Dengue Serotypes Four serotypes: DEN-1, DEN-2, DEN-3, DEN-4. Serotypes differ in genetic makeup, antigenic properties, and geographic distribution. Mosquito Vector The primary vector is Aedes aegypti, a mosquito that bites during the day.

4. Structure of Dengue Virus Shape: Spherical and enveloped, approximately 50 nm in diameter. Envelope: Contains glycoproteins that facilitate virus attachment and entry into host cells. Genome: Composed of a single-stranded, positive-sense RNA, roughly 11 kb in length. Proteins: Encodes for three structural and seven non-structural proteins necessary for virus replication.

5. Dengue Virus Replication Mechanism Attachment: Virus attaches to host cell receptors, initiating endocytosis. Uncoating: The virus releases its RNA genome into the cytoplasm. Translation: The viral RNA is translated into polyproteins. Proteolytic Processing: Polyproteins are cleaved into individual viral proteins by cellular and viral proteases. Replication: Genomic RNA is used as a template for synthesizing new RNA and viral proteins. Assembly and Release: New virus particles are assembled and released from the cell.

6. Pathogenesis of Dengue Virus Infection of Dendritic Cells: The virus enters dendritic cells in the skin via mosquito bites. Dissemination via Lymphatics: The virus spreads through the lymphatic system to other tissues. Platelet Activation: Infected platelets activate and release inflammatory cytokines and chemokines.

7. Transmission Modes of Dengue Virus Mosquito Bites: Transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Vertical Transmission: From mother to fetus during pregnancy or childbirth. Blood Transfusion: Through infected blood transfusion or organ transplantation. Sexual Transmission: Rare, but possible.

8. Symptoms and Clinical Manifestations Mild Dengue Fever: Fever Headache Retro-orbital pain Muscle and joint pain Rash Severe Dengue Fever: Severe headache Joint and muscle pain

9. Symptoms and Clinical Manifestations Bleeding manifestations Plasma leakage Organ impairment Dengue Shock Syndrome: Severe plasma leakage Hypotension Shock Organ failure

10. Laboratory Diagnosis Serology : Detection of IgM and/or IgG antibodies to dengue virus. Molecular : RT-PCR to detect viral RNA. Virus Isolation : Growth in cell culture or animal models.

11. Treatment and Prevention Treatment: No specific treatment; supportive care with antipyretics and analgesics. Prevention: Mosquito control Use of protective clothing and mosquito repellents Vaccination: CYD-TDV vaccine (a live recombinant tetravalent vaccine) provides partial protection against dengue.

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