Dengue Fever : Diagnosis and management .

Dengue fever

1. Title: Dengue: The Most Rapidly Spreading Mosquito-Borne Viral IllnessSubtitle: Epidemiology, Clinical Manifestations, and VectorsPresenter's Name : Dr ATTA Ur Rahman

2. Introduction to Dengue Definition: Dengue is a febrile illness caused by a flavivirus transmitted by mosquitoes. Global Prevalence: Endemic in Asia, the Pacific, Africa, and the Americas. Dengue Virus SerotypesAnnual Infections:400 million total infections 100 million clinically apparent cases

3. Dengue Transmission Principal Vector: Aedes aegyptiBreeds in standing water (e.g., containers, air coolers, tyre dumps)Secondary Vector: Aedes albopictusFound in some South-East Asian countriesVisual: [Insert image of Aedes aegypti mosquito and breeding sites]

4. Dengue Virus Serotypes Four Serotypes: DEN-1, DEN-2, DEN-3, DEN-4 Immunity: Type-specific immunity is life-long. Cross-immunity against other serotypes lasts only a few months.

5. Severe Dengue: DHF and DSS Dengue Hemorrhagic Fever (DHF)Occurs in individuals with prior immunity to a different dengue serotype.Dengue Shock Syndrome (DSS)Associated with severe cases, leading to capillary leak and disseminated intravascular coagulation (DIC).Pathogenesis:Increased uptake of the virus by Fc receptor-expressing cells.Cytokine release causing severe symptoms.

6. Changing Epidemiology Demographic Shifts:Previously common in small children and those aged 2–15.Now more common in children under 2 years and individuals aged 16–45 or older.Geographical Spread:Increasing prevalence in rural areas.Case Fatality: Higher in women

7. Clinical Features Asymptomatic Cases: Common in children.Symptomatic Disease: Referred to as “Dengue” when specific symptoms or signs are present.Initial Symptoms: Undifferentiated fever termed ‘dengue-like illness.

8. Typical Clinical Features Rash: Often follows the initial febrile phase as the fever subsides.Laboratory Findings:LeucopeniaNeutropeniaThrombocytopeniaElevated ALT/AST levels

9. Disease Progression and Warning Signs Uncomplicated Course: Common in many symptomatic infections.Complications: Can lead to severe dengue, especially with atypical features.Warning Signs:Justify intense medical management.Monitor for progression to severe dengue (DHF/DSS).

10. Atypical and Severe Dengue Atypical Features: Increasingly seen, especially in:InfantsOlder patientsRural areasSevere Dengue: Includes DHF, DSS, and other complications:DHF: Dengue Hemorrhagic FeverDSS: Dengue Shock SyndromeMortality Risk: High, requires urgent management.

11. The Critical Phase (3–7 Days After Fever Onset) Signs of DHF/DSS: May develop during this period.Tourniquet Test:Positive test indicates capillary fragility and thrombocytopenia.Progression Indicators:Capillary Leak: Leads to DSS, evidenced by:Raised haematocritTachycardiaHypotensionPleural effusionsAscitesSevere Outcomes: Can progress to metabolic acidosis, multi-organ failure (including ARDS).

12. Hemorrhagic Manifestations Minor Hemorrhage:PetechiaeEcchymosesEpistaxisMajor Hemorrhage:Gastrointestinal bleedingVaginal bleedingSevere Complications: Cerebrovascular bleeding.

13. Serological Diagnosis Seroconversion:IgM Antibodies: Indicative of recent infection.IgG Antibodies: A fourfold rise in titres confirms dengue.Cross-Reactivity:Antibodies may cross-react with other flaviviruses, such as:Yellow Fever VirusJapanese Encephalitis VirusWest Nile Virus

14. Molecular Diagnosis Virus Isolation: Dengue Virus: Can be isolated from blood or cerebrospinal fluid (CSF).PCR Detection:Dengue RNA: Identified using PCR techniques, highly specific.Specialist Laboratories: Typically perform these tests.

15. NS1 Antigen Detection ELISA Kits:Detect NS1 viral antigen.Widely available in endemic areas.Sensitivity: Less than PCR but still useful for diagnosis.Usage: Common in early stages of dengue infection.

16. Comparison of Diagnostic Methods Serology vs. PCR vs. ELISA:Serology: Good for confirming past infections; potential cross-reactivity.PCR: High sensitivity and specificity; detects active infection.ELISA: Convenient for early detection but less sensitive than PCR.

17. Management and Prevention of Dengue. Supportive TreatmentPrimary Focus: Supportive care is crucial in managing dengue.Fluid Replacement: Key to preventing dehydration and managing shock.Management of Shock and Organ Dysfunction:Critical determinant of morbidity and mortality.Intensive care support can reduce mortality rates to 1% or less.

18. Medications to Avoid Aspirin:Risk: Increases the risk of bleeding.Recommendation: Should be avoided in dengue cases.Glucocorticoids:Effectiveness: Not beneficial in treating dengue.Antivirals:Current Status: No effective antivirals for dengue are available.

19. Prevention Strategies: Mosquito Control Elimination of Breeding Sites:Key Actions: Remove standing water in containers, tire dumps, and other breeding sites.Insecticide Use:Purpose: Destroy adult Aedes mosquitoes.Application: Critical in reducing mosquito populations.

20. Vaccination: Current and Future Live Attenuated Tetravalent Chimeric Vaccine:Licensing: Approved in 2019.Target Group: Recommended for children who have already had a first dengue infection and live in endemic areas.Vaccine Limitations:Consideration: Only for those with prior dengue exposure.Future Vaccines:Development: Other vaccines are currently under research.

21. Comprehensive Prevention Approach Combination of Strategies:Supportive Care: Essential for patient survival.Preventive Measures: Focus on mosquito control and vaccination.Public Awareness: Critical for community involvement in prevention.

22. Thank you