Dengue Fever
Brian Rochana
Aurora Cardenas
David Marquez
Dengue Virus Background
•
Family: Flaviviridae
•
ss +RNA
•
genome: 10 proteins
•
3 Structural
• Coat, deliver RNA to target
cells
•
7 Nonstructural
•
Enveloped
•
4 serotypes:
• DEN-1, 2, 3, 4
Goodsell, David. "Dengue Virus." RCSB PDB-101. N.p., n.d. Web. 23 Oct.
2012.
Classification: Group IV
Clinical Characteristics of
Dengue Fever
• Fever
• Headache
• Muscle and joint pain
• Nausea/vomiting
• Rash
Transmission
• Arthropod-borne virus
• Virus contraction from bite
of the carrier Aedes
mosquito
• Lives around human
habitation
Case #3 Businessman and son
• 27 year old businessman
• High fever
• Retro-orbital headache
• Joint & back pain x 5 days
• after return trip from
Malaysia
• symptoms x 4 days
• Rash on palms & soles x2
days
Significance of Malaysia Trip
• Dengue virus occurs
commonly in tropical and
sub-tropical areas
• Malaysia in dengue
epidemic zone
• Aedes carrier mosquito
common in Malaysia
• Dengue is endemic in
Malaysia, occurring every
year
Significance of Malaysia Trip
• Leading cause of illness and
death of children in Malaysia
• Rainy season attracts
mosquitoes to nest in stagnant
water supply
• Infection not biased to rural or
urban areas
• Symptoms usually begin 4-7
days after initial infection
Significance of Malaysia Trip
• Reported dengue illness
steadily increasing since
1988
• All four dengue serotypes
present in Malaysia
• Short-term changes in
weather particularly
precipitation and humidity
correlated with dengue
incidence
Global Cases of Dengue Infection
Diagnosis
Clinical Characteristics of
Dengue Fever
•
•
•
•
•
•
•
Backbone fever, Seven-day Fever, Swahilli-bad spirit
Fever
Headache
retro-orbital eye pain
Muscle and joint pain
Nausea/vomiting
Rash
•
•
•
diffuse erythematous maculo-papular rash
mild hemorrhagic manifestation
Minor epithelial hemorrhage – Petechia – lower extremeties
Diagnosis
• Febrile Phase:
• sudden fever
• last 2-7 days
• facial flushing
• skin erythema
• generalized body ache
• Test: tourniquet test
• mild haemorrhagic
• petechiae
• mucosal membrane bleeding
(nose, gums)
• Progressive decrease in total
white cell count
• Critical Phase
Case # 3 cont. 5-year old son
•5-Year male
•mild flulike symptoms
•collapsed after 2-5 days
•hands cold and clamy
•face flushed
•body warm
•Petechiae present on forehead
•Ecchymoses present
•Bruised easily
•Rapid breathing
•Weak rapid pulse
•Rapidly recovered after 24 hours
Petchiae
•
small round spots
•Bleeding under skin
•Appear red, brown or purple
•Commonly appear in clusters and may look like
a rash.
•Usually flat to the touch
•Don't lose color when you press on them.
Laboratory Testing
• Blood: WBC count
• Serology: Viral IgM , IgG
ELISA, viral culture, PCR
• Imaging: Chest X-Ray
1. What features of these cases pointed to
the diagnosis of dengue virus infection?
• Physical symptoms:
• High fever
• severe headache
• severe joint & back pain
• Rash
• Petechiae
• easy bruising
• Endemic area: Malaysia
2. Of what significance was the trip to
Malaysia?
• The virus has a strong presence in Malaysia.
• The risk of infection is in all parts of the country
• Aedes as the carrier arthropod is found commonly in
Malaysia.
• The country is inside a dengue epidemic zone
• The climate of Malaysia supports the larvae nesting of
the mosquito
•
Cases of dengue infections have been increasing in the
country for over a decade.
3. What was the source of infection in the
father and son?
•
As mentioned earlier, the Dengue virus is contracted from the bite of
an Aedes aegypti mosquito carrying the virus. One single bite from an
infected mosquito can cause disease in host.
•
Virus does not directly from person-to-person.
•
Both the father and the son became infected via a bite from an infected
Aedes mosquito while staying at Malaysia.
4. What were the significance of and the pathogenic
basis for the petechiae and ecchymoses in the child?
• As discussed earlier, petechiae and ecchymoses both refer to
the bleeding that occurs in the skin. Petechiae usually refers to
small lesions while ecchymoses refers to larger lesions.
Ecchymoses are commonly called bruises.
• It is noted that Dengue Hemorrhagic Fever is a specific
syndrome that that tends to affect children under the age of 10.
• The child experiencing symptoms such as bruising easily, a
flushing face, rapid breathing, and a weak pulse, fit the
diagnosis of Dengue Hemmorhagic Fever.
Severe Dengue Fever
• Due to the symptoms the child is facing,
we can infer that the child is suffering
from Dengue Hemorrhagic Fever.
• In this critical phase of the disease,
significant fluid accumulates in the chest
and abdominal cavity due the increased
capillary permeability and leakage.
• Therefore, there is a depletion of fluid
from the circulation as well as a
decrease in blood supply to vital organs,
which is the root of the many symptoms
observed.
DHF
• The increased permeability of the capillaries led to
excess fluid accumulation, which is behind why the
child was able to bruise easily as well as having a
very weak pulse.
• This could lead to the failure of the circulatory
system and shock. Without proper treatment, the
mortality rate of this disease is approximately 20%.
Treatment
• There are no approved vaccines for the Dengue virus.
• However, there is treatment for this disease the can
decrease the mortality rate of this Dengue fever to
2.5%.
• Oral rehydration therapy
• IV fluids and/or bloodstream transfusions
• Pain relievers such as acetaminophen
• Prevention methods can significantly protect from
becoming infected.
Prevention
• The primary method for preventing the spread of Dengue Fever
is by controlling or eliminating the Aedes mosquitoes habitats.
• Reducing open collections of water.
• Wearing clothing the fully covers the skin and using insect
repellent.
• Avoid traveling or living in areas where these mosquitoes and
virus are endemic.