3. Dengue Fever
• A virus infection caused by the dengue
virus
• There are 4 kinds of dengue viruses
• Mosquito transmits this viral disease
4. Areas infested with Aedes aegypti
Areas with Aedes aegypti and recent epidemic dengue
5. Global Status
• New infections annually: 50 million
• Deaths: 24,000 annually
• People at risk: 2.5-3 billion
• Hospitalized cases: 500,000/year
– 90% of those affected are children
• Disease burden: 465,000 Disability
Adjusted Life Years (DALY)
6. Dengue in the Philippines
• Endemic
– 5% mortality rate
– estimated 25,000 deaths/year
• Occurrence: sporadic throughout the
year and high cases usually occur during
the rainy seasons
– June-November
9. Aedes aegypti
• The transmitter of the disease
• “tiger mosquito”
• A daybiting mosquito which lays eggs in
clear and stagnant water found in flower
vases, cans, rain barrels, old rubber tires
• The adult mosquitoes rest in dark places
of the house
10. How do Aedes Mosquitoes
Transmit Disease?
Virus is carried in its
body.
Mosquito bites and sucks And passes the virus
blood containing the virus to healthy people
from an infected person. when it bites them.
11. Incubation Period
• The incubation period of dengue fever
after the mosquito bite is usually 4 to 7
days
13. • Virus strain
• Pre-existing anti-dengue antibody
– previous infection
– maternal antibodies in infants
• Host genetics
• Age
• Higher risk in secondary infections
• Higher risk in locations with two or more
serotypes circulating simultaneously at high
levels (hyperendemic transmission)
14. Increased Probability of DHF
Hyperendemicity
Increased circulation Increased probability
of viruses of secondary infection
Increased probability of Increased probability of
occurrence of virulent strains immune enhancement
Increased probability of DHF Gubler & Trent, 1994
16. ASYMPTOMATIC
Undifferentiated
Fever
Without haemorrhage
SYMPTOMATIC Dengue Fever
With unusual haemorrhage
Dengue No shock
Haemorrhagic
Fever DSS
17. Undifferentiated Fever
• May be the most common manifestation
of dengue
• Prospective study found that 87% of
students infected were either
asymptomatic or only mildly
symptomatic
• Other prospective studies including all
age- groups also demonstrate silent
transmission
25. • Abdominal pain - intense and sustained
• Persistent vomiting
• Abrupt change from fever to
hypothermia, with sweating and
prostration
• Restlessness or somnolence
28. • Blood pressure
• Evidence of bleeding in skin or other sites
• Hydration status
• Evidence of increased vascular
permeability-- pleural effusions, ascites
• Tourniquet test
29. Tourniquet Test
• Inflate blood pressure cuff to a point
midway between systolic and diastolic
pressure for 5 minutes
• Positive test: 20 or more petechiae per 1
inch2 (6.25 cm2)
Pan American Health Organization: Dengue and Dengue
Hemorrhagic Fever: Guidelines for Prevention and Control.
PAHO: Washington, D.C., 1994: 12.
32. • No hemorrhagic manifestations and
patient is well-hydrated: home
treatment
• Hemorrhagic manifestations or hydration
borderline: outpatient observation
center or hospitalization
• Warning signs (even without profound
shock) or DSS: hospitalize
33. Patient Follow-up
• Patients treated at home
– Instruction regarding danger signs
– Consider repeat clinical evaluation
• Patients with bleeding manifestations
– Serial hematocrits and platelets at
least daily until temperature normal
for 1 to 2 days
34. Patient Follow-up
• All patients
– If blood sample taken in first 5 days
after onset, need convalescent sample
between days 6 - 30
– All hospitalized patients need samples
on admission and at discharge or
death
36. Dengue Fever and
DHF I & II
• Fluids
• Rest
• Antipyretics (avoid aspirin and non-
steroidal anti-inflammatory drugs)
• Monitor blood pressure, hematocrit,
platelet count, level of consciousness
37. DHF III & IV
• All above treatment +
• In case of severe bleeding, give fresh
whole blood
• Give platelet rich plasma transfusion
• After BT, continue fluid therapy
38. Indications for Hospital Discharge
• Absence of fever for 24 hours (without anti-
fever therapy) and return of appetite
• Visible improvement in clinical picture
• Stable hematocrit
• 3 days after recovery from shock
• Platelets 50,000/mm3
• No respiratory distress from pleural
effusions/ascites
Pan American Health Organization: Dengue and Dengue Hemorrhagic Fever: Guidelines for Prevention and Control.
PAHO: Washington, D.C., 1994: 69.
40. Do you know that…
• Dengue fever and dengue hemorrhagic
fever are the most common mosquito-
borne viral disease in the world.
• Only the female mosquito feeds on
blood. This is because they need the
protein found in blood to produce eggs.
Male mosquitoes feed only on plant
nectar.
41. Do you know that…
• The mosquito is attracted by the body
odors, carbon dioxide and heat emitted
from the animal or humans.
• The female Aedes mosquito searches for
suitable places to lay their eggs.
• Aedes are day-biters, most active during
dawn and dusk.
43. DHF kills only by hemorrhage
Patient dies as a result of shock
Poor management turns dengue into DHF
Poorly managed dengue can be more severe,
but DHF is a distinct condition, which even
well-treated patients may develop
Positive tourniquet test = DHF
Tourniquet test is a nonspecific indicator of
capillary fragility
44. DHF is a pediatric disease
All age groups are involved
DHF is a problem of low income families
All socioeconomic groups are affected
Tourists will certainly get DHF with a
second infection
Tourists are at low risk to acquire DHF
46. • Cover water drums and water pails at all
times to prevent mosquitoes from
breeding.
• Replace water in flower vases once a
week.
• Clean all water containers once a week.
Scrub the sides well to remove eggs of
mosquitoes sticking to the sides.
47. • Clean gutters of leaves and debris so that
rain water will not collect as breeding
places of mosquitoes.
• Old tires used as roof support should be
punctured or cut to avoid accumulation
of water.
• Collect and dispose all unusable tin cans,
jars, bottles and other items that can
collect and hold water.
