Dengue Fever

Jasmial Nand

Paediatrics

2014

Outline

1. References

2. Introduction

3. Pathogenesis

4. Classification

5. Clinical Course

6. Assessment

7. Investigations

8. Differentials

9. Management

10. Additional Points

11. References

1. References

• Medscape

• Up-to-Date

• WHO Publication

• Dengue Case Management

• CWM ED CME Presentation

• Journal articles

• Tropical Medicine and Int’ Health (2001, 2004)

• Indian Journal of Pediatrics (2006)

• Clinical Microbiology Review (2009)

2. Introduction

• The most common arbovirus globally

• Tropics at risk (approx. 2.5-3 Billion)

• 4 distinct serotypes (1-4)

• Flavivirus (ss RNA)

• Vector-borne (Genus Aedes) but other routes possible

• Common species are aegypti, albopictus and polynesiensis.

• Transmission/ Outbreak patterns

• Usually self limiting, MR <1%,

3. Pathogenesis

Martina B E E et al.

Clin. Microbiol. Rev.

2009;22:564-581

4. Classification

Infection

Asymptomatic Symptomatic

Undifferentiated Dengue Fever

NO Warning Signs

With Warning Signs

Severe Dengue

50-90%

4. Classification (II)

• Dengue fever without warning signs

• Hx of being in endemic area.

• Fever and 2 of the following

• Aches and pains

• Nausea & vomitting

• Rash

• Tourniquet test positive

• Leukopenia

4. Classification (III)

• Dengue with Warning signs

• Fluid accumulation clinically (ascitis, pleural effusion)

• Liver enlargement

• Lethargy (or restlessness)

• Lab (High HCT &/or Low PLT)

• Abdominal pain (or tenderness)

• Vomiting (persistent)

• Insignificant bleeding (Mucosal bleeding)

“Flavi”

4. Classifications (IV)

• Severe Dengue

1. Severe plasma leakage leading to

• Shock

• Fluid accumulation with respiratory distress

2. Severe bleeding as evidenced by a doctor

3. Severe organ involvement

• Liver: AST or ALT >1000

• CNS: Impaired consciousness

• Heart and other organ dysfunctions

5. Clinical Course

• Incubation period (3-7 days)

• Febrile phase (2-7 days)

• Critical phase (1-3 days)

• Marked by defervescence , leukopenia and thrombocytopenia.

• Recovery phase (or Severe Dengue.)

• May have bradycardia. Important to avoid fluid overload!

• Patients can and will present in any of the 3 stages so good history and timeline is critical to know where the patient stands and what to expect next.

5. Clinical Course (II)

• Severe Dengue

• Recognising shock is important. Case fatality as high 12%

• Usually on day 4/5 of illness.

• Pulse pressure is <20mmHg

• Poor capillary perfusion• Cold extremities

• Delayed cap. Refill

• Tachycardia

• Hypotension is often a late sign

6. Assessment

• History

• Important to determine timeline, family history and past infections in mother for infants.

• N.B. Maternal antibodies only protect for first 6 months.

• Physical Exam

• Vitals must be carefully observed and mental state

• Tourniquet test (>20 petechiae/inch2)

• Usu. Non-specific but maculopapular rash, conjunctival injection, pharyngeal oedema, lymphadenopathy and hepatomegaly may be seen in upto 50% of cases.

7. Investigations• Serology:

• Within 3 days NS1 Strip test

• > 3days IgM (Potential for false positive present for 6 days though)

• IgG will indicate secondary infection (A fourfold titre increase is needed)

• Bloods

• FBC- Leukopenia, Changes in HCT.

• PLT- <150,000

• Peripheral blood smear- Transformed lymphocytes

• Albumin- low due to extravasation

• Liver function tests

• Urine output

• CXR, AXR, USS- to pick up fluid accumulation

8. Differentials

Febrile Stage

• Leptospirosis

• Measles

• Typhoid

• Malaria

Critical Phase

• AFI

• As before

• Surgical

• Acute abdomen

• Upper GI Bleed

Use the timeline to differentiate. And these factors favour Dengue: High fever, rash, retro-orbital pain thrombocytopenia, leukopenia, absence of cough, and absence of sore-throat.

9. Management

Steps to take

1. Diagnosis, and classification of phase and severity

2. Deciding if to be sent home, inpatient or emergency referral and treatment.

3. Disease notification

9. Management (II)

• Group A- Outpatient

• No warning signs

• Stable socio-economic status

• Group B- Inpatient

• Warning signs

• Infants

• Poor socio-economic situation

• Malnutrition, concurrent infections

• Group C- Emergency Inpatient

• Severe dengue- Plasma leakage, shock, fluid accumulation, severe bleeds, organ impairment.

9. Management (III)

Group A

• As doctor/clinic

• ORS, PCT, Bedrest, Vigilance

• Schedule daily followups. Monitor FBC, dehydration, warning signs and defervescence

• Family advice

• Control fever (PCT 10-15mg/kg Q6H)

• Prevent dehydration

• Prevent spread within household

• Watch for warning signs as temp drops after 3-8 days.

9. Management (IV)

Group B• Admit. Assess fluid status, FBC and vitals every 4 hours

• Continually monitor for shock and severe dengue

• IV fluids- Crystalloids at 6ml/kg/hr first 2 hours and then reassess and drop to 2-3ml/kg/hr. Maintain urine output and perfusion. Usu. Will pass soon into recovery or severe dengue.

• If HCT and BP stable reduce fluids

• If patient worsens increase to 20ml/kg for 1 hour and assess.

• If danger signs picked up proceed to Group C management

9. Management (V)

Group C- Compensated Shock• Admit to PICU or NICU

• Obtain investigations, assess fluid status and monitor vitals as per ward protocol

• Fluid: 20ml/kg crystalloid over 1 hour and reduce to 10ml/kg for next hour if responsive and then 2-3ml/kg/hr for next 6-8 hours.

• If not improving, change to colloid solution 10-15ml/kg over 1 hour. Revert to crystalloids asap

• Once signs of reabsorbtion seen (bradycardia, rash) taper fluids down to maintenance levels to prevent hypervolaemia.

9. Management (VI)

Group C- Hypotensive Shock or Hemorrhagic

• Admit to Nice or PICU, resuscitate as before.

• If after colloids patient still deteriorates (HCT, etc) transfusion ma be necessary, if HCT drops sharply.

• 5-10ml whole blood slowly over 2-4 hours and monitor HCT.

• Avoid IM injections and movement to prevent further bleeding

9. Management (VII)

Fluid Overload

• Signs• Resp. distress

• Cyanosis

• Ascitis

• Periorbital or soft tissue oedema

• Treatment• Inotropic agents may be needed with small colloid

boluses. Avoid diuretics

• Aspirating large effusions

• PPV before pulmonary oedema develops

9. Management (VIII)

Discharge Criteria

• Clinically

• No fever for 48 hours

• Gen. well-being, appetite, hemodynamic status, urine output all improved and no respiratory distress

• Labs

• Increasing trend of platelets

• Stable HCT without intravenous fluids.

10. Additional Points

• Atypical presentations make for worse prognosis .

• Interestingly, the latest outbreak in Fiji saw a rise in Guillain-Barre syndrome. Currently under investigation.

• Children with suspected dengue can deteriorate very fast and a high index of suspicion is needed on our part.

• Plasma leakage is the most specific and life-threatening feature of severe dengue. Watch for the critical period carefully (Deferevescence) and don’t overload with fluid.

• Primary prevention is the way out as vaccines are not approved yet. Commed’s important afterall!

11. References

• Medscape

• Up-to-Date

• WHO Publication

• Dengue Case Management

• CWM ED CME Presentation

• Journal articles

• Tropical Medicine and Int’ Health (2001, 2004)

• Indian Journal of Pediatrics (2006)

• Clinical Microbiology Review (2009)

The End