Dengue Haemorrhagi

c Fever

WHO SEARO 2011

By : Luthfia Rahmadita10 / 304682 / KU / 14101

KEY FACTS• Some 2.5 billion people – two fifths of the world's population in tropical and subtropical

countries – are at risk.• An estimated 50 million dengue infections occur worldwide annually.• An estimated 500 000 people with DHF require hospitalization each year. A very large

proportion (approximately 90%) of them are children aged less than five years, and about 2.5% of those affected die.

• Dengue and DHF is endemic in more than 100 countries in the WHO regions of Africa, theAmericas, the Eastern Mediterranean, South-East Asia and the Western Pacific. The South-East Asia and Western Pacific regions are the most seriously affected.

• Epidemics of dengue are increasing in frequency. During epidemics, infection rates among those who have not been previously exposed to the virus are often 40% to 50% but can also reach 80% to 90%.

• Primarily an urban disease, dengue and DHF are now spreading to rural areas worldwide.

Dengue Virus

• The dengue viruses are members of the genus Flavivirus and family Flaviviridae. These small (50 nm) viruses contain single-strand RNA as genome.

• Genome: core (C), membrane-associated protein (M), envelope protein (E), nonstructural protein (NS) genes

• There are four virus serotypes, which are DENV-1, DENV-2, DENV-3 and DENV-4

• Aedes (Stegomyia) aegypti (Ae. aegypti) and Aedes (Stegomyia) albopictus (Ae. albopictus) are the two most important vectors of dengue

Transmission

Transmission of DHF• For transmission to occur the female Ae. aegypti must bite an infected

human during the viraemic phase of the illness that manifests two days before the onset of fever and lasts 4–5 days after onset of fever. After ingestion of the infected blood meal the virus replicates in the epithelial cell lining of the midgut and escapes into haemocoele to infect the salivary glands and finally enters the saliva causing infection during probing. The genital track is also infected and the virus may enter the fully developed eggs at the time of oviposition. The extrinsic incubation period (EIP) lasts from 8 to 12 days and the mosquito remains infected for the rest of its life. The intrinsic incubation period covers five to seven days. During dry season: extrinsic incubation period shortened, mosquitoes bite more frequently due to dehydration

Clinical Manifestation

Diagnosis Criteria

Disease Course

Laboratory Diagnosis

• Virus isolation– serotypic/genotypic characterization

• Viral nucleic acid detection• Viral antigen detection• Immunological response based tests

– IgM and IgG antibody assays• Analysis for haematological parameters

• Thrombocytopenia, below 100 000 per μl, may be occasionally observed in dengue fever but is a constant feature in DHF. Thrombocytopenia is usually found between the third and eighth day of illness often before or simultaneously with changes in haematocrit.

• Haemoconcentration with an increase in the haematocrit of 20% or more (for the same patient or for a patient of the same age and sex) is considered to be a definitive evidence of increased vascular permeability and plasma leakage.

• IgM / IgG ratio is to determined whether primary of secondary dengue infection.

Management

Dengue Fever1.Bed rest2.Adequate fluid intake: milk, fruit juice, ORS, isotonic electrolyte solution (no plain water)3.Keep body temperature below 39°C. If temperature goes beyond 39°C, give paracetamol (10mg/kg/dose, max 4gr/day)4.Tepid sponging of forehead, armpits, and extremities

Management

DHF Grade I, II (Non-shock Cases)

1.Same as DF management2.Fluid allowance (oral + IV) is about maintenance (for one day) + 5% deficit (oral and IV fluid together), to be administered over 48 hours

p.s. deficit of 5% is 50ml/kg

Management

DHF Grade III, IV (Shock Cases/DSS)

1.Fluid resuscitation: 10ml/kg in children or 300-500ml in adults over 1 hour or by bolus

2. continued for a minimum duration of 24 hours and discontinued by 36 to 48 hours. Excessive fluids will cause massive effusions due to the increased capillary permeability.

3. Lab investigations:

A — Acidosis: Blood gas analysis

B — Bleeding: Haematocrit

C — Calcium: Electrolyte, Calcium ion

S — Blood Sugar: RBG

Isotonic crystalloid solutions should be used throughout the critical period except in the very young infants <6 months of age in whom 0.45% sodium chloride may be usedHyper-oncotic colloid solutions (osmolarity of >300 mOsm/l) such as dextran 40 or starch solutions may be used in patients with massive plasma leakage, and those not responding to the minimum volume of crystalloidPlatelet transfusion is not recommended for thrombocytopenia (no prophylaxis platelet transfusion). It may be considered in adults with underlying hypertension and very severe thrombocytopenia (less than 10 000 cell/mm3).The duration of intravenous fluid therapy should not exceed 24 to 48 hours for those with shock. However, for those patients who do not have shock, the duration of intravenous fluid therapy may have to be longer but not more than 60 to 72 hours.

Complications

• Fluid overload• Encephalopathy• Renal failure• DIC• Acute pulmonary oedem• Encephalitis • Hepatic and renal dysfunction• Acidosis metabolic• Electrolite and metabolic imbalance

CRITERIA FOR DISCHARGING PATIENTS

Absence of fever for at least 24 hours without the use of anti-fever therapy.Return of appetite.Visible clinical improvement.Satisfactory urine output.A minimum of 2–3 days have elapsed after recovery from shock.No respiratory distress from pleural effusion and no ascites.Platelet count of more than 50 000/mm3. If not, patients can be recommended to avoid traumatic activities for at least 1–2 weeks for platelet count to become normal. In most uncomplicated cases, platelet rises to normal within 3–5 days.

Prevention and Control

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