NS1 and IgM/IgG tests for dengue fever When should a doctor order it

Do you suffer from sudden fever, headache behind the eyes, severe muscle pain, or skin rash?These symptoms could indicate Dengue Fever, a viral infection transmitted by mosquitoes. The Dengue IgM/IgG and NS1 Antigen tests are among the most essential diagnostic tools for detecting the disease in its early or later stages.
In this article from Dalili Medical, we provide a clear and reliable guide to these tests — when they are ordered, how to interpret the results, and why early diagnosis is crucial.

What is Dengue Virus (Dengue)?

Dengue is a viral infection transmitted by the bite of an infected Aedes aegypti mosquito. Common symptoms include:

Sudden high fever
Severe headache, especially behind the eyes
Intense joint and muscle pain
Skin rash
Nausea or vomiting
Mild bleeding (nose or gum)

Blood tests are essential to confirm a dengue infection.

What is the NS1 Antigen Test?

The NS1 Antigen test detects a specific protein secreted by the dengue virus in the blood during the first 1–5 days of illness.

✅ Why is the NS1 Test Important?

Detects dengue infection very early
Helps differentiate dengue from other viral illnesses
Not affected by antibodies (IgM or IgG)

When is it ordered?

When dengue symptoms appear within the first 5 days
During suspected dengue outbreaks in a region

What is the Dengue IgM / IgG Test?

✅ IgM Antibodies Test:

Detects IgM antibodies produced 3–5 days after infection
Indicates a recent or current infection
Levels remain elevated for 1–3 months

✅ IgG Antibodies Test:

Detects IgG antibodies, which appear later
Indicates past infection or long-term immunity
Useful to determine if a person has been exposed to dengue before

Normal Values and Interpretation

Test	Result	Interpretation
NS1 Antigen	Positive	Active infection during early phase (Day 1–5)
IgM	Positive	Recent infection (after 4–7 days of symptoms)
IgG	Positive	Past infection or acquired immunity
IgM + IgG	Positive	Current infection with developing long-term immunity

⚠️ Do Test Results Reflect Severity?

Dengue tests confirm the presence of the virus but do not measure how severe the disease is. Doctors assess severity by combining results with:

Platelet Count
Liver and kidney function tests
Bleeding indicators

How is the Dengue Test Performed?

A blood sample is drawn from a vein
No fasting is required
Results are typically available within 24–48 hours

When Should You Get Tested for Dengue?

If you have symptoms suggestive of dengue
After travel to dengue-endemic areas
During a local outbreak
If you work in healthcare or outdoors in mosquito-prone areas

Dengue Fever vs. Seasonal Flu: Key Differences

Symptom	Dengue Fever	Seasonal Flu
Fever	High and persistent	Mild to moderate
Body aches	Severe (“bone-breaking”)	Mild to moderate
Skin rash	Very common	Rare
Bleeding	Possible	Extremely rare

❓ Frequently Asked Questions (FAQ)

❓ Can I rely only on the NS1 test?

✅ Yes, during the first few days. However, it’s best combined with IgM testing later to confirm the diagnosis.

❓ Is dengue dangerous?

✅ Usually not, but if left untreated, it can lead to serious complications such as:

Dengue Hemorrhagic Fever
Dengue Shock Syndrome

❓ Is there a cure for dengue?

There is no specific antiviral treatment. Rest, hydration, and close monitoring of platelet count are key to managing symptoms and preventing complications.

❓ How can I protect myself from dengue?

Avoid mosquito bites
Use insect repellents
Eliminate stagnant water around your home
Wear long-sleeved clothing

✅ Conclusion:

Dengue IgM/IgG and NS1 Antigen tests are critical diagnostic tools for detecting dengue fever in both early and late stages. Early diagnosis can prevent serious complications.
If you experience dengue-like symptoms, don’t delay—consult your doctor and get tested promptly.