Dengue fever is an acute febrile illness lasting 2-7 days, presenting symptoms such as headache, rash, and hemorrhagic manifestations, primarily transmitted by female Aedes mosquitoes. The clinical spectrum includes dengue fever, dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS), with DHF and DSS involving severe complications like plasma leakage and bleeding. Treatment is mainly supportive, with careful monitoring of platelet counts and hematocrit, while serious cases may require intravenous fluids and blood transfusions.

1. Dengue fever
Dengue fever is an acute febrile illness of 2-7 days
duration ( sometimes with two peaks) with two or
more of the following manifestations:
» headache
» retro-orbital pain
» myalgia /arthralgia
» rash
» haemorrhagic manifestation ( petechiae
and positive tournquet test)
» leukopenia

2. Transmission:
• The disease is transmitted by female Aedes
mosquitoes which are daytime feeders.
• Mosquitoes acquire the virus when they
feed on a carrier of the virus. The mosquito
can transmit dengue if it immediately bites
another host.
• The mosquito remains infected for the
remainder of its 15-to 65-day lifespan.

3. Aedes egypti:

4. Manifestation of Dengue infection
All dengue virus (Den 1,2,3 and 4) infections may
be :
» Asymptomatic.
» Undifferentiated fever
» Dengue fever
» Dengue haemorrhagic fever
» Dengue shock syndrome.

5. Clinical patterns of dengue infection:
► DF
► DHF
► DSS

6. Dengue fever:
• Dengue has an incubation period of 3-14
days( average 4-7 days).
• Following the by 5 to 7 day of acute febrile
illness develops.
• Recovery is usually complete by 7-10
days.
• DHF or DSS usually develops around the
3rd to 7th day of the illness.

7. Symptoms:

8. DHF
In this case there is haemorrhagic tendency
evidence by one or more of the following:
¤ Positive tourniquet test.
¤ Petechiae, ecchymosis or purpura
¤ Bleeding from mucosa ( mostly
epistaxis or bleeding from gums)
¤ Haematemesis or melena.
¤ Thrombocytopenia
¤ Evidence of plasma leakage due to
increased capillary permeability.

9. Bleeding sites:

10. Dengue shock syndrome
This condition is characterized by all criteria
of DHF plus signs of circulatory failure
manifested by rapid and weak pulse,
narrow pulse pressure( < or equal to 20
mmHg); hypotension for age; cold clammy
skin and restlessness.

11. Pathophysiology:
• Pathophysiological abnormalities that occur in
DHF and DSS are plasma leakage and
bleeding.
• Plasma leakage is caused by increased capillary
permeability and may be manifested by
haemoconcentration, as well as pleural effusion
and ascites.
• Bleeding is caused by capillary fragility and
thrombocytopenia and may present in various
ways, ranging from petechial skin hemorrhage to
life-threatening GIT bleeding.

12. DHF & DSS:

13. Laboratory criteria for diagnosis:
Laboratory criteria for diagnosis include one
or more of the following:
►Isolation of dengue virus fro serum,
leukocytes, or autopsy sample.
►4-fold or greater change in IgM or IgG
antibody titres to one or more dengue
virus antigens.
►detection of the virus genome in
autopsy tissues, serum or CSF by PCR.

14. Treatment:
• DF is usually a self-limited illness, and
only supportive care is required.
• Paracetamol may be used to treat patients
with symptomatic fever.
• Aspirin and NSAIDs and corticosteroids
should be avoided.
• Platelet count and hematocrit should be
measured daily from the third day of the
illness.

15. Treatment (contin.):
• Patients who develop signs of dehydration such
as tachycardia, prolonged capillary refill time,
cool skin, small pulse, altered mental status,
decreased urine output, rise in hematocrit,
narrowed pulse pressure or hypotension, require
admission for I.V fluid administration.
• Intravascular volume deficits should be
corrected with isotonic fluids such as Ringer
lactate.
• If these fail, plasma expander may be used.
• Patients with internal or GIT bleeding may need
blood transfusion.

16. Treatment (contin.):
• I.V fluids should be stopped when hematocrit level falls
below 40%.
• The patients may be discharged when they meet the
following criteria:
- Afebrile for 24 hours without antipyretics.
- Good appetite, clinically improved.
- Adequate urine output
- Stable hematocrit
- 48 hours after recovery from shock.
- Absence respiratory distress
- Platelet count greater than 50000.