Dengue Fever — Symptoms, Diagnosis and Treatment

Every monsoon season, I see the same story: a patient with a high fever, a pounding headache and body pain so intense it feels like the bones are breaking. Nine times out of ten, the first question is about platelets. Let me explain what dengue really is and what matters most.

What is dengue?

Dengue is a viral infection caused by one of four related dengue virus serotypes (DENV-1 to DENV-4). Most infections are mild or even silent, but a minority progress to severe disease, formerly called dengue hemorrhagic fever. Recovering from one serotype gives lifelong protection against that type only, and a second infection with a different serotype carries a higher risk of severe illness.

How does dengue spread?

Dengue spreads through the bite of an infected female Aedes mosquito, mainly Aedes aegypti. These mosquitoes breed in clean, stagnant water, such as flower pots, water coolers, discarded tires and roof tanks, and they bite mostly during the day, especially early morning and late afternoon. It does not spread directly from person to person through casual contact. Symptoms usually begin 4 to 10 days after the bite.

Symptoms and warning signs

Classic dengue begins suddenly with high fever, severe headache, pain behind the eyes, muscle and joint pain, nausea, vomiting and a skin rash. The fever lasts about 2 to 7 days.

The most dangerous period is often when the fever settles, around days 3 to 7. This is the critical phase, when plasma can leak from blood vessels. The WHO lists these warning signs:

• Severe abdominal pain or tenderness
• Persistent vomiting
• Bleeding from the gums or nose, or blood in vomit or stool
• Restlessness or unusual drowsiness
• Fluid accumulation, such as in the abdomen or around the lungs
• A rapid drop in platelets with a rising hematocrit

Severe dengue, including dengue hemorrhagic fever and dengue shock syndrome, is a medical emergency and needs hospital care.

How is dengue diagnosed?

The right test depends on how many days you have been sick.

NS1 antigen

NS1 is a viral protein detectable in blood from the first day of illness, and it is most useful in the first 5 days. A positive result confirms dengue, but a negative result later in the illness does not rule it out.

IgM and IgG antibodies

IgM antibodies usually become detectable after day 5, which makes them more reliable later in the illness. IgG appears later and can point to a previous infection. Cross-reactivity with other flaviviruses can occur, so results must be read in context. PCR is also available in some centers.

Alongside these tests, a complete blood count tracks platelets, white cells and hematocrit. These trends tell me more about how sick a patient is than a single number.

Supportive treatment

There is no specific antiviral for dengue. Care is supportive:

• Rest and plenty of oral fluids, such as ORS, water and soups.
• Paracetamol (acetaminophen) for fever and pain. Avoid aspirin and NSAIDs like ibuprofen, which raise bleeding risk.
• Daily monitoring of platelets and hematocrit during the critical phase.
• IV fluids and close observation in hospital if warning signs appear.

A common misconception is that low platelets alone mean a transfusion. Platelet transfusion is generally reserved for significant bleeding, not for a low count by itself.

Prevention

Prevention means controlling the mosquito. Empty and scrub containers holding standing water weekly, cover water tanks, and use window screens, bed nets and repellents. Wear long sleeves during daytime hours. Dengue vaccines exist, but they are restricted to specific age groups and settings, so ask your doctor whether one applies to you.