classification, epidemiology, morphology, pathogenesis, target tissue, Vector of DENGUE virus, symtoms

1. DANGUE
VIRUS
PRESENTED BY
NAVEED UR REHMAN
BS 5TH MICROBIOLOGY

2. Objectives:
1. Introduction
2. Classification
3. What is the Dengue Virus?
4. Epidemiology
5. Morphology of Dengue virus
6. Pathogenesis
7.Target tissues
8.Vector of Dengue virus
9.Symptoms
10.Morbidity and Mortality
11.Diagnostic tests
12.Treatment 13.Prevention

3. Objectives:
1. Introduction 11. Diagnostic tests
2. Classification treatment
3. What is the Dengue Virus? Prevention
4. Epidemiology
5. Morphology of Dengue virus
6. Pathogenesis
7. Target tissues
8. Vector of Dengue virus
9. Symptoms
10. Morbidity and Mortality

4. Introduction
 Dangue virus (DENV) is the cause of dengue fever
 It is a mosquito-borne disease
 It is single positive-stranded RNA virus
 Five serotypes of the virus have been found
 All of which cause the full spectrum of disease

5. Classification
Group: Group IV ((+)ssRNA
Order: Unassigned
Family: Flaviviridae
Genus: Flavivirus
Species: Dengue virus

6. What is the Dengue Virus?
 It is Arbovirus, it can transmitted through arthropods i.e. mosquitoes
 Aedes aegypti is a vector for Dengue virus
 It is a pathogen that causes
 Break bone fever and dandy fever
 Dengue hemorrhagic fever (DHF)
 Can lead to Dengue shock syndrome (DSS)

7.  Most these disease are cause by four different serotypes (DEN-
1,2,3,4)
 First reported epidemics in 1780 in Asia, Africa, and North America

8. Epidemiology
Dengue occurs throughout much of the tropical and
subtropical areas of world

9. Dengue became a world wide problem in the 1950’s
though it rarely affects the US.

10. Morphology of Dengue virus
 Its is an enveloped virus
 It has a roughly spherical shape
 It is ssRNA virus
 It has E and M protein on
envelope membrane

11.  E protein are found as a dimer on the surface of the mature viral
particle
 It is important in the initial attachment of this particle to the host cell
 M (membrane) protein, which is important in the formation and
maturation of the viral particle

12. Pathogenesis
 Humans are initially infected through a mosquito vector
 Initial interaction with cell occurs with the viruses ability to
infect cell
 Primary target, Phagocytes
 Virus uses cell receptor molecule to enter cell
 Cell receptor molecules include:
 Glycosaminoglycan
 Heparan Sulfate (Expressed in almost all cell types)

13.  Virus replicates in target organs
 Virus is released and circulates in blood
 Alternate mosquito then bites host and receives virus

14. Target tissues
 Dengue induces cytokine production in cells
 Cytotoxic factor effects endothelial cells involved in most of the following:
 Heart
 Liver
 Kidneys
 Lungs
 Intestines
 Spleen
 Lymph node
 Brain
 Skin (inflammatory rashes)

15. Vector of Dengue virus
 Its vector is female Aedes aegypti.
 Characteristics of the
Aedes Mosquito:
 One distinct physical feature – black and white
stripes on its body and legs.
 Bites during the day.
 Lays its eggs in clean, stagnant water.
Close-up of an Aedes mosquito

16.  Only the female Aedes mosquito feeds on blood
 They need the protein found in blood to produce
eggs.
 Male mosquitoes feed only on plant nectar.
 On average, a female Aedes mosquito can lay
about 300 eggs during her life span of 14 to 21
days.

17. Life cycle of the Aedes Mosquito
1-2 days
Stagnant water
Pupae
4-5 days
Larvae Eggs
2-3 days

18. How Do Aedes Mosquitoes Transmit
Diseases...
Mosquito bites and sucks
blood containing the virus
from an infected person.
Virus is carried in its
body.
And passes the virus
to healthy people
when it bites them.

19. Symptoms
 Fever
 Headache
 Muscle and joint pain
 Dehydration
 Nausea and/or Hematemesis (vomiting of blood)
 Epistaxis (Bleeding from the nose, mouth,
or gums)
 Haematuria (Blood in Urine)
 Pain behind the eyes
 Respiratory distress
 Petechia (Skin rash) and/or Purpura (Lesions)

20. The more severe form of Dengue is
Dengue Hemorrhagic Fever.

21. Morbidity and Mortality
 More than 2.5 Billion people live in areas that have a risk of
infection
 Over 100 million cases of Dengue infection are reported each year
globally
 500,000 cases pertain to DHF
 DHF has a 5% fatality rate for those infected
 People at high risk are children and the elderly

22. Diagnostic tests
 Virus isolation by infection of mice using infected mosquitoes
 Detection of IgM antibodies in the blood by PCR or Viral isolation
(Serology)
 ELISA (Enzyme-Linked Immunoabsorbent assay)
 Stripe test

23. Treatment
 There is no specific treatment
 Symptomatic treatment is possible
 Vaccination
 Only one vaccine for dengue is currently approved in three countries
(Brazil, Mexico, Philippines).
 Several vaccines are under development by private and public
researchers
 Developing a vaccine against the disease is challenging

24.  With four different serotypes of the dengue virus that can cause
the disease, the vaccine must immunize against all four types to
be effective.
 Vaccination against only one serotype could possibly lead to
severe dengue hemorrhagic shock (DHS) when infected with
another serotype due to antibody-dependent enhancement.
 When infected with dengue virus, the immune system produces
cross-reactive antibodies that provide immunity to that particular
serotype.

25.  However, these antibodies are incapable of neutralizing other
serotypes .
 Upon reinfection and actually increase viral replication.
 When macrophages consume the ‘neutralized’ virus, the virus is able
to replicate within the macrophage, causing disease
 These cross-reactive, ineffective antibodies ease access of virus into
macrophages, which induces more severe disease (dengue
hemorrhagic fever, dengue shock syndrome).

26. Prevention
Prevent Aedes from Breeding!
Remove ALL sources of stagnant water.
Deny the Aedes mosquito of any chance
to breed.

27. Change water in vases on alternate days.

28. Remove water from flowerpot plates on alternate
days.

29. Turn over all pails and water storage containers.

30. Use a mosquito net

31. Use insecticides spray and lotions

32. Thank you