dengue KISHORE SOWRAN microbiology presentation.pptx

Microbiology

1. CAUSATIVE AGENT OF DENGUE BY: KISHORE SOWRAN R S 223-A

2. Taxonomy - Classification within the Flaviviridae family: Dengue virus is classified into the genus Flavivirus along with other medically important viruses such as Zika virus and Yellow fever virus. - Subtypes: Dengue virus comprises four distinct serotypes (DENV-1, DENV-2, DENV-3, and DENV-4), each with its unique genetic characteristics and antigenic properties. - Importance of understanding taxonomy for epidemiology and vaccine development: Taxonomic classification facilitates epidemiological surveillance, vaccine development, and understanding of viral evolution and emergence of new strains.

3. Morphology - Dengue virus is an enveloped, single-stranded RNA virus with a spherical shape. - Structure: The viral particle consists of a nucleocapsid core surrounded by a lipid bilayer envelope derived from the host cell membrane. - Viral Components: Key components include the capsid protein, which encapsulates the viral RNA genome, and envelope glycoproteins (E and prM ), involved in viral entry and immune evasion.

4. Epidemiology Dengue fever is endemic in over 100 countries, predominantly in tropical and subtropical regions of Asia, the Americas, and Africa. - Distribution: Dengue transmission is influenced by factors such as climate, urbanization, population movement, and vector ecology, leading to varying patterns of transmission intensity and geographic spread. - Incidence: Dengue incidence has been increasing globally, with millions of cases reported annually and periodic outbreaks occurring in endemic areas. - Impact on public health and healthcare systems: Dengue places a substantial burden on healthcare systems, with significant economic and social consequences, particularly in resource-limited settings.

5. Etiology - Etiology of Dengue Virus Infection: Dengue virus is primarily transmitted to humans through the bite of infected Aedes mosquitoes, primarily Aedes aegypti and Aedes albopictus. - Transmission: Mosquito-borne transmission occurs when mosquitoes acquire the virus by feeding on viremic humans and subsequently transmit it to other susceptible individuals. - Reservoirs: Humans are the primary reservoir for Dengue virus, but non-human primates may also play a role in sylvatic transmission cycles. - Factors contributing to dengue virus transmission dynamics: Urbanization, population growth, travel, and climate change contribute to the spread and persistence of Dengue virus transmission cycles.

6. Cultural Properties - Cultural and Societal Aspects of Dengue Virus: Cultural beliefs, practices, and socioeconomic factors influence dengue prevention and control efforts in affected communities. - Impact on Communities: Dengue outbreaks can lead to social stigma, economic hardship, and disruption of daily life, particularly in marginalized communities. - Cultural Practices: Water storage habits, waste management practices, and mosquito control measures may vary across cultures and affect dengue transmission dynamics. - Importance of cultural sensitivity in dengue prevention efforts: Effective prevention strategies should consider cultural norms, beliefs, and community engagement to promote sustainable behavior change and reduce dengue transmission.

7. Virulence Factors - Virulence Factors of Dengue Virus: Dengue virus possesses several virulence factors that contribute to its pathogenicity and ability to cause disease in humans. - Role of Viral Proteins: Key viral proteins such as NS1 (non-structural protein 1), NS3, and NS5 play crucial roles in viral replication, immune evasion, and modulation of host immune responses. - Host Immune Response: Dengue virus infection triggers complex interactions between the virus and the host immune system, leading to immune-mediated tissue damage, cytokine dysregulation, and vascular leakage. - Relationship between virulence factors and disease severity: Viral virulence factors influence disease outcomes, with certain viral strains and host factors predisposing individuals to more severe forms of dengue, including dengue hemorrhagic fever and dengue shock syndrome.

8. Pathogenicity - Pathogenic Mechanisms of Dengue Virus: Dengue virus infects and replicates in target cells of the immune system, leading to systemic viral dissemination and tissue damage. - Target Cells: Dengue virus primarily infects monocytes, macrophages, and dendritic cells, disrupting normal immune function and contributing to immunopathogenesis. - Immune Evasion Strategies: Dengue virus employs various strategies to evade host immune responses, including antigenic variation, inhibition of interferon signaling , and modulation of host cell apoptosis. - Mechanisms of tissue damage and disease progression: Dengue pathogenesis involves a complex interplay between viral factors, host immune responses, and vascular dysfunction, leading to manifestations such as plasma leakage, thrombocytopenia, and hemorrhage .

9. Lab Diagnosis - Laboratory Diagnosis of Dengue Virus Infection: Timely and accurate diagnosis of dengue virus infection is essential for patient management, outbreak response, and surveillance purposes. - Diagnostic Tests: Laboratory tests for dengue diagnosis include detection of viral antigens (e.g., NS1 antigen test), nucleic acid amplification tests (e.g., PCR), and serological assays (e.g., IgM/IgG antibody tests). - Importance of early and accurate diagnosis for patient management: Early diagnosis enables appropriate clinical management, including fluid resuscitation, monitoring for warning signs, and timely referral for severe cases requiring hospitalization. - Challenges and limitations of laboratory diagnostics: Diagnostic tests for dengue may vary in sensitivity, specificity, and availability, and interpretation of results may be complicated by cross-reactivity with other flaviviruses and timing of specimen collection.

10. Treatment - Treatment of Dengue Virus Infection: Currently, there is no specific antiviral therapy for dengue virus infection, and management primarily focuses on supportive care to alleviate symptoms and prevent complications. - Supportive Care: Supportive measures include fluid management to prevent dehydration, analgesics for pain relief, antipyretics to control fever, and monitoring for signs of severe dengue requiring hospitalization. - Role of Antiviral Therapies: Investigational antiviral drugs and immunomodulatory agents are being evaluated in clinical trials, but no approved antiviral therapy is available for routine clinical use. - Importance of early intervention and close monitoring for severe cases: Early recognition of warning signs and prompt medical intervention are critical for preventing progression to severe dengue and reducing mortality rates associated with severe dengue complications.

11. Prevention - Prevention Strategies for Dengue Virus Infection: Dengue prevention relies on integrated approaches targeting vector control, personal protection measures, and community engagement to reduce mosquito-borne transmission. - Vector Control: Strategies include environmental management to eliminate mosquito breeding sites (e.g., removing stagnant water containers, covering water storage containers), insecticide spraying in high-risk areas, and biological control methods (e.g., larviciding ). - Personal Protection Measures: Individuals can protect themselves from mosquito bites by using mosquito repellents, wearing long-sleeved clothing and pants, using bed nets, and staying indoors during peak mosquito activity periods. - Community Engagement: Engaging communities in dengue prevention efforts through educational campaigns, community clean-up drives, and mobilizing local resources fosters ownership and sustainability of vector control initiatives.