Causes of viral haemorrhagic fever :

1. Dengue
2. Yellow fever
3. Lassa fever
4. Ebola fever
5. Marburg fever
6. Crimean-Congo haemorrhagic fever.
7. Rift Valley fever.
8. Kyasanur fever
9. Bolivian and Argentinian haemorrhagic fever
10. Hantan fever (haemorrhagic fever with renal syndrome).

Case of Definition of dengue fever :

Define :  Dengue fever is an acute febrile illness of 2-7 days duration sometimes with two peaks having the following manifestations

1. Sudden onset continuous fever. And
2. Two or more of the following features

• Retro orbital pain severe myalgia / arthralgia/back pain.
• Severe headache
• Hemorrhagic manifestation.
• Nausea/vomiting/abdominal pain.
• Rash

Causative organism of dengue fever :

Dengue virus, which is a flavi virus. It has 4 serotypes.

Vector :

• Aedes aegypti.
• Aedes albopictus.

Types/manifestations of dengue infection :

1. Asymptomatic infection
2. Symptomatic infection :

• Undifferentiated fever (viral syndrome).
• Classical dengue fever.
• Dengue haemorrhagic fever
• Expanded dengue syndrome.

Symptoms of dengue fever :

1. Fever : 

• Three is sharp rise of temperature frequently associated with flushed face and headache.
• Temperature usually between 39° C to 40° C.
• Lasting 2-7 days is most cases.

  2. Rash:

• First 2 3 days – diffuse flushing or fleeting eruption may be seen in face, neck and chest
• 3rd and 4th day a conspicuous rash that may be maculopapular or rubelliform.
• Afebrile period or defervescence – Petechiae surrounding scattered pale, round areas of normal skin may appear over the dorsum of the feet, on the legs and on the hands and arms.

3. Other feature :

• Retro-orbital pain on eye movement or eye pressure.
• Photophobia.
• Backache and pain in the muscles and joints/bone.
• Anorexia and altered taste sensation, constipation, colicky abdominal pain and abdominal tenderness.

Investigations of dengue fever :

1. Complete blood count: Leukopenia & thrombocytopenia.
2. ELISA to detect NSI antigen
3. Antibody titre : Four-fold rise in IgG titre
4. Isolation of dengue virus from blood.
5. Detection of dengue virus RNA by PCR.

Treatment of dengue fever :

• Symptomatic treatment.
• Aspirin should be avoided due to bleeding risk.
• Volume replacement and blood transfusions may be indicated in patients with shock.
• Corticosteroids have not been shown to help.
• No existing antivirals are effective.

Management of dengue shock syndrome :

1. Immediate volume replacement by crystalloid solution (10-20 ml/kg/h for 1-2 hour).
2. If improved, then reduction of crystalloid 20 to 10, to 6, to 3 ml/kg/h and maintain the I/V therapy: for 24-48 hour.
3. If no improvement, then immediate oxygen inhalation and do the hematocrit level.

• If hematocrit rises, I/V colloid infusion, if improves then I/V crystalloid solution continued for 24-48 hour.
• If hematocrit decrease, blood transfusion and if improves then crystalloid infusion should be continued up to 24-48 hour.

Case definition of dengue shock syndrome :

Dengue shock syndrome is a presentation of dengue syndrome when a case of dengue manifests circulatory failure with one or more of following features :

1. Hypotension for age.
2. Cold clammy skin, restless, rapid weak pulse.
3. Narrow pulse pressure.
4. Profound shock.

Prevention of dengue fever :

• Breeding places of Aedes mosquitoes should be abolished.
• Adult mosquitoes are destroyed by insecticides.
• There is no licensed vaccine available.

Criteria of severe dengue fever :

1.. Severe plasma leakage leading to :

• Shock (dengue shock syndrome).
• Fluid accumulation with respiratory distress.

2.  Severe haemorrhagic manifestations, e.g. GI haemorrhage.

3. Severe organ involvement :

• Liver AST or ALT 21000 U/L
• CNS : inpaired consciousness, meningoencephalitis, seizures.
• Cardiomyopathy, conduction defects, arryhythmias.
• Other organs, e.g, acute kidney injury, pancreatitis, acute lung injury, disseminated intravascular coagulopathy, rhabdomyolysis.

Complications of dengue fever :

1. Dengue haemorrhagic fever and dissiminated intravascular coagulation.
2. Dengue shock syndrome.
3. Severe organ involvement : hepatitis, cerebral haemorrhage or oedema, encephalitis, cranial nerve palsy, rhabdomyolysis, myocarditis.

Indications for hospital admission :

1. Very weak, poor appetite or severe dehydration.
2. Presence of warning signs
3. Significant bleeding
4. WBC 5000 cell/mm’ in high risk group (Infants, elderly, pregnancy, prolonged shock, significant bleeding, underlying disease, neurological manifestations).
5. Platelet count 100000 cell/mm and presence of weakness, poor appetite.
6. Rising het 10-20%
7. No clinical improvement and weakness when no fever
8. Less urine in 4-6 hours.
9. Extreme family anxiety
10. Shock or impending shock-

• No fever but rapid pulse
• Capillary refill
• Cold, clammy extremities, skin motling.
• Imitable, restless, confusion
• Pulse pressure 20 mmhg.
• Fainting postural hypotension.