dengue and its features

1. DENGUE
Dr.MADHUMITA SINGH
PG GENERAL MEDICINE
1

2. DENGUE IS ALSO KNOWN AS
Philippine hemorrhagic fever
Thai hemorrhagic fever
Singapore hemorrhagic fever
Onyong- Nyang Fever
West Nile Fever
Dandy fever
Break Bone Fever
Dengue like Disease
2

3. CAUSATIVE AGENT
Dengue virus is a Arbovirus from the
genus Flavivirus
Single stranded RNA virus
Four species – Den 1,2,3,4
Infection with one serotype provides
lifelong immunity for that species.
Transmitted by mosquito ,Aedes aegypti
closely associated with human
habitation.
3

4. ADES AEGYPTI MOSQUITO
Lays its eggs in clean, stagnant water.
One distinct physical feature – black and white
stripes on its body and legs – Tiger mosquito
Bites during the day.
On average, a female Aedes mosquito can lay
about 300 eggs during her life span of 14 to 21
days.
Only the female Aedes mosquito feeds on blood.
This is because they need the protein found in
blood to produce eggs. Male mosquitoes feed only
on plant nectar
4

5. Dengue virus life cycle

6. 5

7. EPEDIOMOLOGY
Rapid expansion of urbanization
Inadequate closed drainage
↑ movement of human population within and
between countries
Insecticide resistance in mosquito vector
population are few of the reasons for ↑ dengue
transmission in recent years
6

8. 7

9. CLINICAL FEATURES
a) Classic Dengue – Break Bone fever
Incubation period is 4 – 6 days ( range 3 -14)
Abrupt onset of fever, chills, headache, retro
orbital pain and backache
Fever is 39 – 40◦ C; remission of 2days followed by
second febrile phase for 1 -2 d.
Biphasic curve or saddle back fever.
Fever lasts for 5- 7 days
8

10. Transient generalized erythematous rash – first 24 – 48
hrs. This morbilliform rash appears on trunk, spreads to
face and limbs sparing palms and soles. It lasts for 1 - 5
days.
Generalised myalgias, arthralgia and constitutional
symptoms like anorexia, nausea, vomiting and dysgeusia
may be +nt.
Relative bradycardia and generalised lymphadenopathy
may be +nt.
Marked leucopenia and thrombocytopenia.
↓ Platelets is due to impaired megakaryocyte production
& ↑ platelet destruction.
9

11. 10

12. 11

13. 12

14. b) Dengue Hemorrhagic fever
Is defined as acute febrile illness with minor
or major bleeding, thrombocytopenia (platelet
≤ 1.0 lakh/mm) & evidence of plasma leakage-
>hemoconcentration (↑hematocrit ) & pleural
or other effusions ( serositis).
Primarily in children and young adults.
Susceptibility ↓ after 12 yrs of age.
DHF, DSS develops arround 3rd to 7th day
+ve Tournquet test – inflate the BP cuff
13

15. on upper arm to midway between systolic and
diastoic BP for 5 min. +ve test > 20 petechiae/ 2.5
cm square. Also known as Hess Test.
Petechiae, bruised skin ,S/c bleeding in
venipuncture site seen in most cases.
Transudate due to excessive capillary leakage leads
to pleural effusion & ascites.
Progressively ↓platelet count, ↑ hematocrit
indicate probability of impending shock.
14

16. 15

17. c) Dengue shock syndrome
DSS is DHF with signs of circulatory failure
Warning signs are intense, sustained abdominal
pain,persistent vomiting, restlessness or lethargy &
sudden change from fever to hypothermia with
sweating and prostration.
Pt. may recover with i/v fluids, but shock may
recur.
Once shock sets in ,mortality is high, 12 -44%
16

18. WHO case definitions
Probable case – An acute febrile illness
with 2 or more of following – Headache,
retro-orbital pain, myalgia & arthralgia,
nausea & vomiting, skin rash, hemorrhagic
manifestations ;
AND
supportive serology
OR
occurrence at the same location & time
as other confirmed cases of Dengue.
17

19. Confirmed Case
Confirmation of the Dengue case is based on Lab
criteria. Virus isolation from serum or tissue
samples.
OR
Demonstration of 4 fold rise in IgG or IgM antibody
titers
in paired serum samples.
OR
Demonstration of Dengue antigen in tissue, CSF by
immunocytochemistry or detection of genomic
sequence
by PCR.
18

20. CRITERIA FOR DHF
19

21. CRITERIA FOR DSS
DSS requires all the DHF criteria in
addition a circulatory failure manifested by
- Rapid and weak pulse
- Narrow pulse pressure ( < 20 mm Hg)
- Hypotension, For age > 5yrs < 90 mm Hg
for age < 5 yrs < 80 mm Hg
- Cold dry skin, restlessness
20

23. LAB DIAGNOSIS
1. Culture of the virus from serum obtained during
febrile phase. Remains detectable in blood during
febrile period.
2. Serologic diagnosis – by demonstrating a rise in
antibody titer in paired sera drawn 7 to 14 days
apart (This could be by any method like
haemagglutination inhibition, complement fixation
or, neutralizing anibodies)
Rise in IgM antibody is more specific for recent
infection; rising titer more specific.
21

24. 3. Newer techniques like RT-PCR ( reverse
transcriptase polymerase chain reaction) are very
sensitive & specific for detecting viral RNA.
4. Thrombocytopenia & hemoconcentration
5. Drop in platelets to , 1.0lakh/mm3 is seen between
3rd to 8th day of illness
6. Hemoconcentration, with ↑ in hematocrit by 20% is
definitive evidence of ↑ vascular permeability &
plasma leakage
22

25. 7. Leucopenia (↓ TLC) & neutropenia; towards
the end of febrile phase
8. Relative lymphocytosis
9. Deranged RFT & LFT & prolonged PT is seen
in severe cases of DHF
23

26. 24

27. DIFFERENTIAL DIAGNOSIS
Any acute febrile illness with
thrombocytopenia
1. Malaria
2. Leptospirosis
3. Infectious mononucleosis
4. Chickungunya
5. Viral hepatitis
6. Sepsis
7. Meningococcimeia
8. Influenza
9. Other hemorrhagic fever
25

28. 26

29. CLINICAL MARKERS OF DENGUE
Continuous fever
Characteristic myalgia ( retro orbital &
interscapular)
Palatal petechiae
Conjunctival suffusion
Magenta colored tongue
Maculopapular rash
Facial flush
Hypotention
Hemorrhage
Dengue fever Adhikari Prabha; Dengue fever,
Medicine Update, Vol 16,2006, API
19- Sep-13
27

30. TREATMENT
Symptomatic - Paracetamol for fever &
myalgia.
Aspirin, NSAIDS avoided due to risk of erosive
gastritis and bleeding.
Rest
Oral rehydration
In DHF careful & repeated estimation of
volume status & fluid replacement is corner-
stone of management. Use isotonic i/v fluids. 28

31. TREATMENT 2
Because patients have loss of plasma they
must be given isotonic solution or plasma
expanders.
Platelets are replaced if the count is less than
10000 /mm3 or clinical bleeding is +nt. It is
better to give Single donor apheresis Platelets
(SDAP) as compared to RDP to lower the risk of
alloimmunization
29

32. TREATMENT 3
Besides bleeding other complications are
ARDS,renal failure, hepatic failure &
encephalopathy.
30

33. PREVENTION AND CONTROL
It is by control of mosquitoes which live & breed in
stagnant water in and around the house.
Lays eggs preferentially in jars, discarded containers,
coconut shells, old tires etc.
Year round breeding
Tropical regions like India are its favorite zones.
How to prevent mosquito spread?
Do not allow empty vessels, coconut shells, plastic
containers, flower pots, tires etc to collect rain water
in them
Frequently (once in 2-3 days) empty all water storage
containers
31

34. PREVENTION AND CONTROL 2
Vector control can be done by simple measures like
using insect repellants, indoor space spray
insecticides .
How to prevent mosquito bites?
Screen your homes with mosquito screens like
Netlon .
Wear full clothing – long sleeves
Apply mosquito repellents like Odomos, Goodnignt
Keep Dengue fever patient under mosquito net
32

35. Vaccination against dengue
The first dengue vaccine, Dengvaxia® (CYD-TDV) developed by
Sanofi Pasteur was licensed in December 2015 and has now
been approved by regulatory authorities in ~20 countries.
WHO position on the CYD-TDV vaccine( WHO UPDATED-9
NOV.2019)
As described in the WHO position paper on the Dengvaxia
vaccine (September 2018) the live attenuated dengue vaccine
CYD-TDV has been shown in clinical trials to be efficacious and
safe in persons who have had a previous dengue virus infection
(seropositive individuals). However, it carries an increased risk
of severe dengue in those who experience their first natural
dengue infection after vaccination (those who were
seronegative at the time of vaccination). Vaccination should be
considered as part of an integrated dengue prevention and
control strategy.
33

36. REFERENCES
 THE BMJ CLINICAL REVIEW-2015 UPDATES AND 2004 UPDATES
 WHO RECENT PUBLICATION (2019, 4TH, NOVEMBER)
 HARRISONS PRINCIPAL OF INTERNAL MEDICINE 20TH EDITION
 API TEXT BOOK OF MEDICINE

37. 34