All about dengue

1. DR ANJANA NAIR A

3.  Genus: Flavi virus
 4 serotypes: DENV -1,2,3,4
 Cross protection only for few
months
 Life long protection
 Genotypes (Subtypes) DENV1-3
 DENV 2-2
 DENV 3-4
 DENV 4-4

4.  3 structural protein genes: C, M, E
 Non structural protein genes:
NS1,2A, 2B,3,4A,4B,5
 NS1- diagnostic value

5.  Female Aedes mosquito(Aegypti, Albopictus)
 Aedes- day time feeder (&twilight), 400 m
 Eggs in damp places--------- 7days- adult emerges
 Dry------ 1year
 Rain---- survival of vectors longer

7.  Rain - Temp, humidity
 16- 30 C
 60-80 % humidity
 Altitude
 Cool shady places

8.  Humans, lower primates
 Infants
 Travel, migration

11.  Extrinsic incubation period : 8-10 days
 Intrinsic incubation period : 4-7 days (3-14)
 Blood transfusion, organ transplantation
 Congenital

13. CYTOKINE TSUNAMI!!
Mononuclear
cells

14.  “A double edged sword”
 non neutralising cross reacting antibodies
 Ab-Ag(virus) complex ----- enhanced uptake by Ig receptor containing cells

15. Widen gap
junctions(transien
t endothelial
dysfunction)

18. DENGUE FEVER WITHOUT WARNING
SIGNS
DENGUE FEVER WITH WARNING SIGNS
SEVERE DENGUE FEVER
DENGUE FEVER (DF)
DENGUE HEMORRHAGIC FEVER(DHF)
DENGUE SHOCK SYNDROME (DSS)

20.  Clinical features: An acute febrile illness of 2-7 days duration + 2/more of following:
- Headache
-Retro orbital pain
-Myalgia/bone pain
-Arthralgia
-Rash
- Hemorrhagic manifestations

21.  DF +
 + Hemorrhagic manif evidenced by 1/more of foll:
- Positive tourniquet test
- Petechiae, ecchymoses or purpura
-Bleeding from mucosa, GIT, injn sites or other sites
 + Thrombocytopenia ( < 1 lkh /mm3)
 + evidence of plasma leakage manifested by 1/more of foll:
- rise in avg HCT for age and sex >/= 20 %
- > 20 % drop in HCT following vol replacement compared to baseline
- signs of plasma leakage (pleural effusion, ascites, hypoproteinemia)

22.  Test to assess Capillary fragility
 BP cuff to mid point b/w SBP & DBP (120/80 100)
 5 MINS
 >/= 10 petechiae in 1 square inch over forearm
 DHF: 20
 Neg/ mild positive in profound shock

23.  All the previous criteria + circulatory failure :
- Restlessness
- Cold clammy skin
-rapid,thready pulse
- Narrow pulse pressure( </= 20 mmHg)
- Hypotension for age (SBP < 90 mmHg)
- reduced urine o/p

24. WARNING SIGNS AND
SYMPTOMS
 Persistent vomiting
 Abdominal pain/tenderness
 Clinical fluid accumulation-(Pleural effusion/ Ascites)
 Mucosal Bleeding
 Lethargy, Restlessness
 hepatomegaly > 2 cm
 Increase in HCT with rapid fall in Platelet count

25.  Severe plasma leakage – shock or fluid accumulation + resp distress
 Severe bleeding
 Severe organ involvement ( AST/ALT >/= 1000 u/l, impaired consciousness, organ
failure)

26.  Unusual presentations
 Comorbidities/coinfections

27.  A case compatible with clinical criteria during outbreak or
 Non ELISA based NS1 antigen/IgM positive(RDT)

28.  A case compatible with clinical criteria + 1 or more of:
 Isolation of virus ( culture) from serum, plasma or leucocytes
 IgM Ab by ELISA positive in single serum sample
 Antigen by NS1 ELISA
 IgG sero conversion in paired sera after 2 weeks with 4 fold rise in titre
 Viral nucleic acid detection by PCR

29. Febrile
Critical
Convalescent

30.  High grade - 2-7 days, Biphasic (5 %)
 Head ache, eye pain ( 60-70 %)
 Rash (50 %)- 1st > 2 nd – D2- D5- macular/maculopapular- face,trunk, extremities, pruritus
+/-
 Breakbone fever
 O/E: Conj redness, pharyngeal erythema, lymphadenopathy, hepatomegaly, bleeds
 Leucopenia, thrombocytopenia, raised AST (2-5 times), synthetic liver function (aPTT
normal)

31.  D3-D7
 36- 48 hrs
 Plasma leakage, Bleeding , Shock( early- narrow PP)
 Mod- Severe thrombocytopenia
 Rising HCT
 aPTT inc, fibrinogen low( transient)
 Imaging- CXR, USG Abdomen, chest

32.  Leaked ECF returns to circulation
 After D6-D7
 For days-weeks
 Rash- white islands in red sea( pruritic)-5 days
 Complication: Pulmonary oedema

33.  Viral Hgic fevers- Ebola, Marburg, Lassa, YF, CCHF, Hanta
 Chikungunya
 Zika Virus
 Malaria
 Enteric fever
 Leptospirosis
 Viral hepatitis
 Rickettsial infection
 Influenza
 COVID
 Meningococcal infection

35.  1st 5 days- Nucleic acid by RTPCR
 Antigen – NS1 – 1st week (1-5)
 IgM – after 4 days(ELISA) (2-3 months)
 IgM seroconversion b/w paired acute and recovery phase(10-14 days after acute
phase)
 4fold / greater rise in Ab titre.
 Serology unreliable in : Vaccinated( recent months),recent infection/ vaccination
with an antigenically related flavi virus- yellow fever , Japanese encephalitis, zika
virus.
 Virus culture

38.  No comorbidities/ high risk factors
 Near normal blood counts (Plt > 1,00,000)
 Tolerating oral fluids
 Adequate urine output
 No Warning signs

39.  Bed Rest
 Tepid sponging
 Antipyretics- Paracetamol ( No NSAIDSs)
 ORS
 Warning signs during critical phase

40.  Fluid management guided by PR,BP,PP,RR,GCS, Temp,Urine o/p,HCT
 Improvement in VS and HCT: Taper fluids
 VS worsening + HCT falling : Internal bleeding- Blood transfusion

41. Chart 1. volume replacement algorithm for patients with moderate Dengue Fever (DHF grades I & II)
41

42.  Vitals every 2-3 hours
 HCT every 4-6 hours
 Urine o/p every 4-8 hours
 Goal: Urine o/p: 0.5-1 ml/kg/hr

43. Chart 2. Volume replacement algorithm for patients with Severe Dengue Fever (DHF grades III)
43

44.  VS every 1-2 hours
 HCT every 4-6 hours( Bleeding- every 1-2 hours)
 Reassess clinical status at completion of crystalloid infusion
 Colloid: 10% Dextran 40 in NS preferred

45. Chart 3. Volume replacement algorithm for patients with Severe Dengue Fever (DHF IV (DSS))
45

46.  VS every 15 mins till stable and hourly thereafter
 HCT every 1-2 hours
 Reassess clinical status every 1-2 hours

47.  NO bleeding- plt <10,000
 Bleeding +/- thrombocytopenia
 Severe bleed + coagulopathy- PRBC/FFP
 No role for Whole blood in managing thrombocytopenia

48. 48
CRITERIA FOR DISCHARGE OF PATIENTS
• Absence of fever for at least 24 hours without the
use of anti-fever therapy
• No respiratory distress from pleural effusion or
ascites
• Platelet count > 50 000/ cumm
• Return of appetite
• Good urine output
• Minimum of 2 to 3 days after recovery from shock
• Visible clinical improvement

49. 1)PERSONAL PROTECTION-
 Mosquito repellants(DEET)
 Insecticides
 Vaccines

50.  CYD-TDV(Dengvaxia)- Live attenuated
-4 Chimeric yellow fever- 17D dengue vaccine viruses (preM, E proteins replace the
same in YF 17D backbone virus)
-WHO- 9-45 years with confirmed previous dengue infection who live in endemic areas.
(Not for seronegative individuals)
-0,6,12 months
-Not for travellers visiting enedemic areas
 TAK-003- Tetravalent vaccine
 Attenuated lab derived DENV2 virus- genetic back bone for all 4 viral strains, other 3
are chimeras generated by replacing preM and E genes of TDV-2 with those from
DENV1,3 and 4
-Both in seronegative and seropositive individuals

51. 2)MOSQUITO CONTROL
 Reduce breeding sites
 Larva control- Copepods feed on larva
 Endosymbiotic control- Mosquitos infected with Wolbachia less vulnerable to
DENV

52.  Which is the cardinal feature that distinguishes DHF from DF??
a) Thrombocytopenia (<1,00,000)
b) Bleeding manifestations (Positive tourniquet test)
c) Evidence of plasma leakage
d) Both b and c
e) All of the above