What Causes Dengue Fever? All You Need to Know

Fever, fatigue, body aches, and rash are common symptoms that can be triggered by a range of illnesses, but when they appear together during the monsoon or post-monsoon months, dengue fever could be the underlying cause. Understanding what causes dengue fever, how it spreads, and how it is diagnosed is essential for timely action.

This blog answers the most frequently asked questions related to the cause, danger, and diagnostic methods for dengue fever, especially if you or a loved one are experiencing symptoms or living in an area with recent outbreaks.

What Causes Dengue Fever?

Dengue fever is caused by the dengue virus (DENV), which has four related but distinct types: DENV-1, DENV-2, DENV-3, and DENV-4. It is not spread from person to person directly. Instead, the virus is transmitted through the bite of infected female mosquitoes, primarily Aedes aegypti and Aedes albopictus.

These mosquitoes become carriers when they bite a person already infected with the virus. Once infected, the mosquito can transmit the virus to other humans for the rest of its life.

So if you're wondering what is the reason for dengue fever, it comes down to the bite of a mosquito carrying the dengue virus — typically during daylight hours, with peak biting activity in the early morning and before dusk.

What Is the Reason for Dengue Fever Outbreaks?

Several environmental and social factors contribute to outbreaks:

• Stagnant water in containers, tires, flowerpots, and construction sites provides breeding grounds.
• Urbanization without proper sanitation or drainage encourages mosquito proliferation.
• Increased travel and mobility can spread the virus between regions.
• Climate conditions, especially humid and rainy seasons, increase mosquito population growth.

Preventive measures often focus on mosquito control and limiting breeding sources.

Is Dengue Fever Dangerous?

The severity of dengue fever can vary widely. Some people experience only mild flu-like symptoms, while others may face more severe outcomes. Severe dengue (also known as dengue hemorrhagic fever or dengue shock syndrome) can involve:

• Bleeding
• Low platelet count
• Leaky blood vessels
• Organ impairment

Early detection and supportive care can significantly reduce the risk of complications. While not all dengue cases become serious, asking “Is dengue fever dangerous?” is valid, especially for children, older adults, or those with weakened immune systems.

How Many Days Does the Dengue Virus Stay in the Body?

The dengue virus typically remains in the human body for about 7–10 days after the onset of symptoms. However, the duration can vary depending on the individual’s immunity and the specific virus strain.

• Incubation period: 4–10 days after the bite
• Febrile phase: Usually 2–7 days with high fever and symptoms
• Recovery or critical phase: May follow with improvement or complications

Even after symptoms subside, some fatigue and weakness can persist for days or even weeks.

How to Identify Dengue Fever in a Blood Test

Because the symptoms of dengue fever can resemble other viral illnesses, blood tests are essential for confirmation. If you're asking how to identify dengue fever in a blood test, here are some markers doctors usually look for:

• Low platelet count (thrombocytopenia)
• Low white blood cell count (leukopenia)
• Elevated hematocrit levels
• NS1 antigen positivity
• Presence of dengue-specific IgM or IgG antibodies

These values help healthcare providers determine the phase and severity of infection.

What Type of Blood Test for Dengue Fever Is Done?

There are several blood tests commonly used to detect dengue:

1. NS1 Antigen Test
   
   
   • Best used in the early days (day 1–5) of illness
   • Detects viral protein in blood


2. IgM and IgG Antibody Tests
   
   
   • Detect the body’s immune response to dengue
   • IgM usually becomes detectable ~5 days after symptoms start
   • IgG appears later and can indicate past infection


3. RT-PCR (Reverse Transcription Polymerase Chain Reaction)
   
   
   • Identifies the presence of viral RNA
   • Often used for early, accurate diagnosis.

Each test has its own diagnostic window. Your healthcare provider may recommend one or more depending on the duration and severity of symptoms.

When to Do a Blood Test for Dengue Fever?

If you’re unsure when to do a blood test for dengue fever, the timing depends on your symptoms:

• Day 1 to Day 5 of symptoms: NS1 antigen or RT-PCR tests are usually recommended.
• After Day 5, IgM and IgG antibody tests become more useful.
• If symptoms worsen or platelet count drops: A complete blood count (CBC) may be repeated daily or as advised by your doctor.

If you’ve had a persistent fever for more than two days with body pain, rash, or signs of dehydration, it’s best to consult a doctor and consider testing.

Conclusion

Understanding what causes dengue fever and recognizing its symptoms early can help you make informed decisions about your health. From identifying the virus in your system to understanding what type of blood test for dengue fever is needed, every step plays a role in timely care and recovery.

Remember, dengue cannot be treated with antibiotics. Supportive care, hydration, and rest are typically recommended under medical supervision. If you’re experiencing symptoms or live in a dengue-prone area, timely testing can make a big difference.

Apollo Diagnostics offers a wide range of diagnostic services, including advanced dengue testing panels, to help you and your family stay safe and informed during mosquito season. Speak to a healthcare provider today if you suspect dengue or need guidance on when to get tested.