Dengue Flashcards
What is the causative agent of DF?
DENV virus (RNA virus)
Family: Flaviviridae
Genus: Flavivirus
Species: Dengue Virus
How many different strains of related DENV virus are there?
four, each serotype has a specific lifetime immunity
What is an arbovirus?
arthropod-borne virus
What is the vector of DF?
Aedes aegypti
Mode of transmission of DF
similar to Malaria
- female mosquito sucks an infected human’s blood
- virus is ingested into its gut and then moves to the salivary gland
- the mosquito can transmit DENV virus for the rest of its life
When does Aedes aegypti typically bite?
early morning and late afternoon
How is the life cycle of DENV virus like?
- virus transmitted to human in mosquito saliva
- virus replicates in target organs
- virus infects WBCs and lymphatic vessels
- virus is released and circulate in blood
- mosquito ingests blood with virus
- virus replicates in mosquito midgut and other organs, infect salivary glands
- virus replicates in salivary gland
What is the incubation period of DENV virus?
4-10 days after bite from an infected mosquito
Describe clinical features of DF.
- fever
- headache
- muscle and joint pain
- nausea / vomiting
- rash
Explain stage 1 of DF: Acute fever stage
- patient have high fever, body ache, abdominal pain, nausea
- anti-pyritic (paracetamol) is important to lower body temperature and minimise body fluid loss
Explain stage 2 of DF: Critical stage
- patients are restless, weak, fast pulse
- important to provide IV fluid to patients
What are the two possible reaction in patients going through Stage 2 (Critical Stage)?
patients w/o increase in capillary permeability - improve w/o going through critical phase
patients w/ increased capillary permeability - worsening of symptoms with subsidence of high fever
- may cause blood plasma to leak out of small blood vessels ➡️ BP drop
- severe cases: patients vomit up blood, have internal haemorrhage and die with circulatory failure or respiratory failure due to internal bleeding
Explain stage 3 of DF: Recovery Phase.
- Gain back appetite
- Bradycardia: slower pulse rate
- Recovering rash at legs and arms
- Diuresis - increased urine production
Explain Severe Dengue Hemorrhagic Fever (DHF).
- a person previously exposed to one serotype infected by a different serotype
- immune system overreacts, causing high fever known as dengue shock syndrome
- DHF can cause death through endothelium dysfunction and disordered blood clotting
What can endothelium dysfunction lead to?
leakage of fluid from blood vessels into the chest and abdominal cavities.
