Dengue FeverBrian Rochana

Aurora CardenasDavid 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.