The document discusses dengue fever, including its origins, epidemiology, transmission, clinical features, diagnosis, and laboratory tests. It provides details on dengue virus serotypes, the disease progression and definitions of dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. Rapid tests and other laboratory diagnostics for dengue are also outlined.

1. Dr. Arifa Akram Barna
Medical officer
Department of Virology
Institute of Epidemiology Disease Control and Research,
DGHS, DHAKA.
Bangladesh
Scenario

2. • The origins of the word dengue are not clear, but one
theory is that it is derived from of Swahili language
“Ki-Dinga pepo” meaning one type of Fever with
severe bone pain and rashes.
• The disease was first reported in Africa during the
19th century.
Origin

3. Epidemiology
• About 112 countries including Bangladesh had
been facing dengue throughout the world.
• Annual incidence is about 100 million people.
Among them, over 500,000 are cases of
Dengue haemorrhagic fever (DHF) and Dengue
shock syndrome (DSS).
• Mortality rate in complicated dengue is about
50%.

4. Bangladesh situation
•First Outbreak in 1960 as Dhaka fever
•In 2000 a huge outbreak of Dengue occurred in Bangladesh
with about 5541 cases with 93 deaths
•Occurs almost in every year
Both vectors are common
(Aedes aegypti Aedes albopictus) &
Aedes albopictus is found commonly in Chittagong

6. One distinct physical feature – black and
white stripes on its body and legs
.

7. Seasonality
Tropical regions are its favorite zones.
Occurs in rainy season
- (May to September)
High humidity
-Longer mosquito survival

8. Dengue is now endemic in > 100 countries
in different parts of the world

9. Causative agent
• Flaviviridae family
• RNA, single stranded, enveloped virus
• 4serotypes i.e Den-1, Den-2, Den-3 and Den-4.
Incubation period
• Ranges from 3-14 days, most often 4-7 days.

10. Transmission
Transmitted by the bite of infected
several species of mosquito within the genu
Aedes, principally A. aegypti and Ades
albopictus. Both Vectors are
common in Bangladesh.

11. Clinical features
Dengue Fever starts with:
1. High fever (1040
F) with chills
2. Headache
3. Pain upon moving the eyes
4. Muscle pain (backache) and joint pain
5. Nausea and vomiting
6. A characteristic rash appears along with
the fever and spreads from the
extremities to entire body except the
face.

12. Clinical course
• This painful "breakbone" and febrile phase lasts 2-7 days
• followed by a rapid drop in body temperature (defervescence) with
profuse sweating.
• A second rapid rise in temperature follows.

13. There are actually four dengue clinical syndromes:
1. Undifferentiated fever
2. Classic dengue fever
3. Dengue hemorrhagic fever, or DHF and
4. Dengue shock syndrome, or DSS.

14. Clinical Case Definition for Dengue Hemorrhagic Fever
4 Necessary Criteria:
1. Fever, or recent history of acute fever
2. Hemorrhagic manifestations
3. Low platelet count (100,000/mm3 or less)
4. Objective evidence of “leaky capillaries:”
• elevated hematocrit (20% or more over baseline)
• low albumin
• pleural or other effusions

15. Clinical Case Definition for Dengue Shock
Syndrome:
4 criteria for DHF
+
Evidence of circulatory failure manifested indirectly by
all of the following:
•Rapid and weak pulse
•hypotension
•Cold, clammy skin and altered mental status

16. Hemorrhagic Manifestations of Dengue
•Skin hemorrhages:
petechiae, purpura, ecchymoses
•Gingival bleeding
•Nasal bleeding
•Gastrointestinal bleeding:
Hematemesis, melena, hematochezia
•Hematuria
•Increased menstrual flow

17. Haemorragic Menifestation

18. Warning signs that may occur at or after defervescence
(the presence of one or more of these signs indicates the
need for immediate medical evaluation):
• Abdominal pain or tenderness
• Persistent vomiting
• Clinical fluid accumulation (i.e., pleural effusion or ascites)
• Mucosal bleeding
• Lethargy or restlessness
• Liver enlargement (≥2cm)
• Increases in hematocrit concurrent with rapid decrease in
platelet count

19. Laboratory diagnosis
The following laboratory tests are done to diagnose
dengue fever and DHF:
• Virus isolation in cell culture
• Nucleic acid detection by PCR
• Viral antigen detection NS1
• Serology
• Others

22. Virus isolation by cell culture:
• when the samples are collected within 6 days
Viral antigen detection by ELISA/ dot blot assay
• Viral antigen detection helps in early diagnosis of the disease
a) Viral non-structural protein 1 (NS1) antigen
– Appears at Day 1 of fever and declines to undetectable
levels by 5–6 days
b) Viral envelope protein antigen

23. RT-PCR
• Is a valuable diagnostic tool with high sensitivity and
specificity
• It also avoids interference due to cross-reactivity of
dengue serotypes with other flaviviruses
• These tests are more accurate than antigen
detection, but are not widely available due to greater
cost

24. Serology
Following serological tests are done:
• Rapid test for detection of IgM and IgG antibody
• IgM antibody capture (MAC)-ELISA
• Haemagglutination-Inhibition test
• Neutralization test
• Dot-blot immunoassay
• Complement fixation test

25. Dengue serotyping
Serotypes of Dengue virus are determined using following test:
• Immunofluorescent staining.
• PCR
Others
• CBC including total leucocyte count, total platelet count and
haematocrit
• Chest X-Ray
• USG
• Serum albumin,LFT, serum electrolyte

26. Rapid test (ICT)
• Qualitative presumptive detection of IgM and IgG in
human serum, plasma and whole blood.
Assay procedure
• Add 10µl of serum using a micropipette.
• Allow the sample to absorb entirely into the
specimen pad within the circular
• Add 2 drops of buffer
• Read the result exactly 15 minutes after adding the
buffer to the cassette.
• Any trace of a pink line in the test area indicates a
positive result.

27. Rapid test (ICT)

28. Interpretation of results
Primary infection---
• Pink bands appear in the IgM and Control regions
• suggestive of primary dengue infection.
Secondary infection----
• Pink bands appear in the IgM, IgG and Control
regions.
• suggestive of a secondary dengue infection

29. Negative----
• A pink band appear in the Control region only.
• No detectable IgG and IgM antibodies to
dengue. The result does not exclude dengue
infection. Retest in 3-4 days if dengue infection
is suspected
Invalid---
• No pink band appears in the Control region.
• The test is invalid and should be repeated.

30. Change water in vases on alternate days.

31. Remove water from flowerpot plates on
alternate days.