Dengue Fever

dengue transmission via aedes albopictus mosquitoes

Dengue fever is a pressing public health issue, especially in tropical regions like Malaysia, where warm and humid conditions enable mosquitoes to thrive.

With annual dengue cases on the rise, awareness is vital for its prevention and control.

What is dengue disease?

Dengue fever is a viral illness caused by the dengue virus (DENV) and spread through bites from infected Aedes mosquitoes, mainly Aedes aegypti and Aedes albopictus.

These mosquitoes are abundant in tropical and subtropical climates, making affected regions more vulnerable to outbreaks.

The virus has four distinct serotypes (DENV-1 to -4), meaning a person can contract dengue up to four times in their lifetime from different strains.

Phases of Dengue Fever

The progression of dengue fever is typically divided into 3 stages:

Febrile Phase (Days 1–5):

This phase begins suddenly, marked by a high fever (exceeding 40°C), headaches, pain behind the eyes, muscle and joint aches, nausea, vomiting, and rashes.
Mild bleeding, like gum bleeding or bruising, may occur.
Patients are most infectious to mosquitoes during this phase due to high viral loads.

Critical Phase (Days 4–7):

When the fever subsides, some patients enter the critical stage, which lasts 24–48 hours.
This phase involves plasma leakage, a drop in platelet count, and severe complications such as bleeding, organ failure, or shock.
Immediate medical attention is crucial since this phase can be life-threatening.

Recovery Phase (Days 7–10):

The body starts reabsorbing spilled fluids, and platelet levels recover.
Symptoms improve considerably, though lingering fatigue is common.
Some patients develop an itchy "convalescent rash" as the body heals.

How long does dengue fever last?

The primary dengue fever spans 7 to 10 days. However, full recovery, particularly from fatigue, can take 2 to 4 weeks.

Post-dengue fatigue syndrome occasionally hampers daily activities and overall quality of life.

Is dengue fever contagious?

Dengue cannot spread directly between people. The dengue virus requires an infected Aedes mosquito as its vector.

Aedes mosquitoes, active during early mornings and late afternoons, feed on infected individuals and then transmit the dengue viruses when they bite others.

This makes mosquito control and protective measures key to preventing the disease.

Symptoms and Warning Signs

Symptoms appear 4 to 10 days after being bitten by an infected mosquito. They range from:

High fever (above 40°C/104°F)
Severe headache and pain behind the eyes
Muscle and joint pain
Nausea, vomiting, fatigue, and skin rash (in half the cases)
Mild bleeding (nosebleeds or gum bleeding)

Dengue Haemorrhagic Fever

Severe dengue manifests with plasma leakage, fluid buildup, organ impairment, and internal bleeding. The ALL-LOVES acronym helps identify these risks:

Abdominal Pain
Liver Enlargement
Low Platelet, High Haematocrit
Lethargy (Restlessness)
O (Nothing)
Vomiting & Diarrhoea
Effusion (Fluid in Chest)
Significant bleed

Dengue Test and Platelet Count

severe disease called dengue hemorrhagic fever or dengue shock syndrome

Accurate diagnosis of dengue involves:

NS1 Antigen Test: Detects dengue virus early (1–5 days post-infection).
IgM and IgG Antibody Tests: IgM indicates recent dengue infection; IgG shows past exposures.
RT-PCR: Identifies viral RNA and serotypes, effective in early infection.
Complete Blood Count (CBC): Essential for evaluating severity according to platelet levels:
- Normal Platelet Count: From 150,000 to 450,000 per μL
- Mild Thrombocytopenia: Less than 150,000 per μL
- Severe Thrombocytopenia: Less 50,000 per μL

Treatment and Management

Hydration and Fever Management:
- Adequate hydration prevents shock and organ failure.
- ORS, clear fluids, or IV therapy may be required.
- Treat fever and pain with paracetamol, avoiding NSAIDs due to bleeding risks.
Monitoring and Supportive Care:
- Track vital signs and platelet counts during the critical phase.
- Severe cases may necessitate hospitalisation.
Rest and Symptom Relief:
- Ample rest aids recovery.
- Cool compresses can offer comfort.

How to prevent dengue?

Prevent Mosquito Bites:
- Apply insect repellents with DEET or oil of lemon eucalyptus.
- Wear protective clothing when outdoors, especially during peak mosquito activity.
- Use mosquito nets, screens, or barriers to shield sleeping areas.
Control Mosquito Populations:
- Use mosquito traps, coils, or UV zappers indoors.
- Participate in community efforts like fogging to control outbreaks.
Eliminate Breeding Sites:
- Clear standing water in containers, gutters, or discarded items.
- Regularly clean water in vases or plant saucers.
Personal and Household Measures:
- Employ air conditioning or permethrin-treated clothing for added protection.
- Consider mosquito-repellent plants like citronella or lavender near entryways.