DENGUE VIRUS

• Dengue virus is responsible for dengue fever.

• Transmitted to human through the bite of infected Aedes mosquitoes( Aedes aegypti, Aedes albopictus).

MORPHOLOGY

• Shape: Spherical shape.

• Size: Approximately 50 – 70 nanometers (nm).

• Symmetry: Icosahedral symmetry

• Envelope: Envelope present in dengue virus

• Single-stranded RNA virus.

• The genome contains three structural proteins (Capsid, Envelope, & Membrane) & seven non-structural protein.

• The Dengue virus has four main serotype DEN-1, DEN-2, DEN-3, and DEN-4.

PATHOGENESIS

• Dengue virus is the most common arbovirus found in India.

• Also called Break-bone fever.

  # Source of infection:

  • People infected with Dengue virus serve as the reservoir or source of infection & Aedes aegypti mosquito.

    # Mode of transmission:

  • Aedes mosquitoes (Aedes aegypti and Aedes albopictus).

  # Incubation period:

  • approximately from 4 to 14 days.

• Primary dengue infection occur when a person is infected with dengue virus for first time with any one serotype.

• Month to year later a more severe form of dengue illness may appear called secondary dengue infection.

# Clinical classification:

1. Mild dengue

o Characterized by fever, headache, joint & muscle pain

o illness is generally self limiting & not cause severe complication

2. Severe dengue

o Characterized by high fever, muscle & joint pain

o Lymphodenopathy

o Loss of appetite

3. Dengue Hemorrhagic fever(DHF)

o DHF is severe form of dengue characterized by

o Low platelet count (thrombocytopenia)

o High grade fever

o Hepatomegaly

o Hematocrit

4. Dengue shock syndrome(DSS)

o All the criteria of DHF is present in DSS the additional manifestation of shocks are

o Rapid & week pulses

o Hypotension

o Cold & clammy skin

# Symptoms:

o Fever

o Headache

o Joint and Muscle Pain

o Pain Behind the Eyes

o Nausea

o Vomiting

o Fatigue

o Loss of Appetite

o Abdominal Pain

o Difficulty in breathing

o Swollen Lymph Nodes

LABORATORY DIAGNOSIS

1. Specimen:

o Whole blood

o Serum

2. Isolation of virus:

o Isolation of virus is difficult but serology play a major role in diagnosis.

o Dengue virus can be isolated from blood or serum onto cell culture.

3. Molecular test:

o Polymerase chain reaction

o Reverse transcriptase polymerase chain reaction

4. Serological test:

o Enzyme linked immunosorbent assay (ELIZA)

5. Neutralization test:

o Virus neutralization test (VNT)

6. Complete blood test:

o Platelet count usually decrease in number.

TREATMENT

• No specific antiviral treatment for Dengue fever is available.

• In severe cases intravenous fluids (IV) may be administered to maintain fluid balance.

• Paracetamol for reduce pain & fever

• In severe cases platelet transfusion also helpful

PROPHYLAXIS

• Vaccination is best option for prophylaxis

PREVENTION

• Wear long sleeved clothes such as shirt, paint, shocks, etc.

• Empty water daily from those area where water hold.

• Use bed net for sleeping especially in those area where aedes aegypti mosquito present

• Use insect protection gel & sprays.