Dengue Fever: Symptoms, Warning Signs, Home Care and When to Go to Hospital

Dengue is a mosquito-borne viral illness that is common in Sri Lanka, especially during and after the monsoon rains. Most people recover at home, but a minority develop severe dengue, which can cause shock and bleeding and can be fatal. Knowing the early symptoms, and especially the warning signs that appear as the fever settles, can save lives.

How dengue spreads

Dengue is spread by the bite of infected Aedes aegypti and Aedes albopictus mosquitoes. These breed in small collections of clean stagnant water, such as flower pots, tyres, coconut shells, plastic containers, gutters and water tanks. They bite mainly in the early morning and late afternoon. Dengue does not spread directly from person to person.

Symptoms

Symptoms usually start 4-10 days after the bite and include:

• sudden high fever (often 39-40 °C);
• severe headache and pain behind the eyes;
• muscle, bone and joint pain;
• nausea and vomiting;
• skin rash, which may appear after a few days;
• mild bleeding such as nosebleeds or bleeding gums in some cases.

These resemble other illnesses such as influenza, leptospirosis and chikungunya, so a doctor's assessment and blood tests are important.

The three phases of dengue

1. Febrile phase (days 1-3 or so): high fever, aches, flushing and headache.
2. Critical phase (around days 3-7): as the fever falls, some patients get worse. Plasma can leak from blood vessels, causing low blood pressure, fluid in the chest or abdomen, and a dropping platelet count. Patients may feel better because the temperature is lower, yet this is the most dangerous time.
3. Recovery phase: fluid returns to the circulation, appetite improves and a rash with itching may appear.

Warning signs that need hospital care immediately

Go to the nearest hospital the same day if there is any of the following, especially around the time the fever falls:

• severe or persistent abdominal pain or tenderness;
• repeated vomiting or being unable to drink;
• bleeding from the nose, gums, vomit or stools, or black stools;
• unusual sleepiness, restlessness or irritability;
• cold, clammy or pale hands and feet;
• very little urine, or none for 6-8 hours;
• breathlessness, fast breathing or fainting;
• swelling or fluid in the abdomen.

In children, refusing feeds, constant crying, a floppy or drowsy state, and cold limbs are danger signs.

Home care for mild dengue

If your doctor says you can be managed at home:

• Rest and avoid strenuous activity.
• Drink plenty of fluids: water, oral rehydration solution, king coconut water, rice kanda (rice porridge), soups and fruit juices. A useful goal is pale yellow urine passed regularly.
• Fever: use paracetamol only, at the dose advised for age and weight. Do not exceed the daily maximum. For children, see our paracetamol dose calculator and always check the label.
• Avoid aspirin, ibuprofen, diclofenac, mefenamic acid and other anti-inflammatory painkillers, as well as injections into muscle.
• Sponge with lukewarm water if the fever is high, and dress lightly.
• Attend daily review with a full blood count (FBC), as your doctor advises, to monitor platelets and haematocrit. Falling platelets are expected and are not by themselves a reason for a transfusion.
• Keep a record of fluid intake, urine output and temperature.

Please note that a normal-looking platelet number does not exclude plasma leakage, so symptoms must be watched even if the count appears acceptable.

Who is at higher risk?

Infants, pregnant women, older adults, people with diabetes, heart, kidney or liver disease, obesity, and those who have had dengue before are at higher risk of severe disease and usually need closer monitoring, often in hospital.

Hospital treatment

Treatment is supportive. Doctors give intravenous fluids carefully, monitor blood pressure, pulse, urine output and blood tests, and treat shock or bleeding if it occurs. Blood products are used selectively. Most patients recover fully with timely care.

Prevention

• Destroy breeding sites: every week, empty and scrub containers, cover water tanks and clear gutters and coconut shells. A few minutes on a fixed day, for example Sunday, makes a difference.
• Protect from bites: use repellents, long sleeves, window screens and bed nets for sick people and babies.
• Stay alert during outbreaks and follow local health authority advice.
• Vaccines: dengue vaccines exist in some countries, and availability and recommendations vary. Ask your doctor about current options.

Common myths

• "The patient is better because the fever has gone." Not necessarily. Days 3-7 are the critical period.
• "Platelets must be raised with medicines or juices." Platelet counts follow the course of the illness. Only a doctor should decide on transfusion.
• "Antibiotics treat dengue." Dengue is a virus, so antibiotics do not help unless there is a separate bacterial infection.

When to see a doctor

Consult a doctor if you have a fever lasting more than two days, particularly during a dengue season or when others nearby have it. Do not wait for a rash. Get urgent help for any warning sign listed above.

References

• World Health Organization: dengue and severe dengue fact sheet; Dengue Guidelines for Diagnosis, Treatment, Prevention and Control
• Sri Lanka Ministry of Health, National Dengue Control Unit: clinical management guidelines
• Centers for Disease Control and Prevention: dengue clinical guidance