Dengue Fever: How to Recognise It and What You Must Not Take

What Is Dengue Fever and How Does It Spread?

Dengue fever is a viral illness carried by the Aedes aegypti mosquito, a small insect with distinctive white markings on its legs and body. This mosquito is different from the malaria mosquito in one key way: it bites during the day, particularly in the early morning and late afternoon, not at night. That means bed nets alone are insufficient protection.

The virus does not pass directly from person to person through touch, air or food. A mosquito bites an infected person, picks up the virus, and then injects it into the next person it bites. Controlling the mosquito is therefore the central pillar of prevention, not avoiding contact with sick people.

Dengue circulates in hot, humid areas where Aedes mosquitoes breed easily. In our region, repeated outbreaks have been documented in Yemen, parts of Saudi Arabia, and Sudan. A 2019 study published in Emerging Infectious Diseases documented a major dengue surge in Taiz, Yemen during the ongoing conflict, highlighting how the disease exploits disrupted urban environments where water storage becomes uncontrolled.

Dengue Symptoms: What Happens in the First Days

Symptoms usually appear three to fourteen days after the mosquito bite, most commonly four to seven days later. Fever is the first and most consistent sign, often rising sharply to 39 to 40 degrees Celsius or higher. The fever may drop and then spike again over the course of a week, which is a pattern that can mislead families into thinking recovery has begun.

Alongside the fever, most patients experience a severe headache behind the eyes, and intense muscle and joint pain so pronounced that dengue has historically been called breakbone fever. Nausea, vomiting and fatigue are common. A red skin rash often appears around the third to fifth day, spreading across the trunk and limbs.

The rash has a characteristic appearance of small red spots that may merge into larger patches. However, do not wait for a rash to suspect dengue. Some patients, particularly young children, never develop one. In areas where dengue is circulating, any high fever lasting more than two days warrants a blood test.

Warning Signs That Need Emergency Care Right Now

Dengue is classified into three levels of severity: uncomplicated dengue, dengue with warning signs, and severe dengue. The vast majority of infections are uncomplicated and resolve within a week to ten days without hospital admission. However, a minority of patients progress to dangerous disease during the critical phase, which typically coincides with the fever suddenly dropping around days four to six. Many families mistake this drop for recovery.

A 2024 review published in the Journal of Intensive Medicine found that patients who required intensive care for severe dengue had almost universally passed through a recognisable warning sign phase that was either missed or dismissed. Recognising these signs early and going to hospital saves lives.

Why Aspirin and Ibuprofen Are Forbidden in Dengue

This point is critically important and causes entirely preventable deaths. When dengue infects you, the virus attacks platelets (the blood cells responsible for clotting and stopping bleeding). Platelet counts fall steadily during illness and can reach dangerously low levels in severe cases.

Aspirin, ibuprofen, diclofenac and all other non-steroidal anti-inflammatory drugs (NSAIDs) work partly by impairing platelet function. Giving these drugs to a dengue patient who already has falling platelet counts dramatically multiplies the bleeding risk. Taking them during dengue is comparable to removing the brakes from a car that is already on a steep slope.

The only safe medicine for fever and pain in dengue is paracetamol, taken at the correct dose for your weight. Do not exceed the maximum daily dose shown on the packet. Excess paracetamol harms the liver, and dengue itself already stresses liver function. If you are unsure of the correct dose, ask a pharmacist or doctor before taking it.

How Is Dengue Diagnosed? What Blood Tests Are Used?

Dengue cannot be reliably diagnosed from symptoms alone because its presentation overlaps with many other fevers. A blood test is necessary to confirm the diagnosis and to monitor the illness. Two types of tests are used. The NS1 antigen test detects a viral protein in the blood and works best in the first five days of fever. The PCR test is more accurate but more expensive and not always available in smaller clinics.

After day five, antibody tests (IgM and IgG) are used, which detect the immune response rather than the virus itself. Your doctor will choose based on when you present and what is locally available. Beyond diagnosis, a full blood count repeated every one to two days during the illness tracks the platelet count and haematocrit, giving early warning of impending severe disease.

A rising haematocrit alongside falling platelets is a signal that plasma is leaking from blood vessels, which is the mechanism behind dengue shock syndrome. This is why regular blood monitoring is not a formality but a genuine lifesaving tool in moderate and severe cases.

How to Care for a Dengue Patient at Home

There is no approved antiviral drug for dengue. Treatment is supportive: managing symptoms, replacing fluids lost through fever and sweating, and watching closely for warning signs. Most otherwise healthy adults recover at home if they follow the guidance carefully. The goal is to help the body through the illness while preventing the complications that make dengue dangerous.

Hydration is the foundation of management. The patient needs to drink large volumes of fluids, at least eight to ten cups of water or oral rehydration solution per day. Fever and sweating cause significant fluid losses, and dengue additionally causes plasma to leak from blood vessels during the critical phase, making consistent fluid intake protective. Coconut water is a reasonable option for replacing electrolytes. Guava juice is promoted in popular culture as a way to raise platelet counts, but the scientific evidence for this claim is limited. Adequate fluid intake of any clear liquid is beneficial regardless of what is consumed.

Give paracetamol for fever and body pain only, and stick to the dose written on the packet. For children, calculate the dose by body weight, not by age alone. Do not exceed the maximum daily dose: excess paracetamol stresses the liver, and dengue already does the same, so getting the dose right matters more in this illness than in an ordinary fever.

Monitor the patient closely every few hours and check for the warning signs listed above. Keep a simple written log of temperature readings, fluid intake and any new symptoms. This record is genuinely useful when you see a doctor, since it replaces guesswork with an actual illness timeline. If the patient cannot keep fluids down, refuses to drink, or has not passed urine in six hours, do not wait. These signs mean that home management is no longer safe and hospital assessment is needed.

Eliminating Dengue Mosquitoes Around Your Home

The Aedes aegypti mosquito lays its eggs in clean standing water, which distinguishes it from many other mosquitoes. A flower pot saucer, an uncovered water tank, the tray under an air conditioning unit, an old tyre holding rainwater, or even a bottle cap with a few drops in it can produce hundreds of mosquitoes within days. Because this mosquito typically flies short distances, the source of dengue in a neighbourhood is often within the same street or compound.

A 2016 household survey in Taiz, Yemen found that many families were unaware that the primary breeding sources were inside or immediately around their homes rather than from distant sources. Addressing this misunderstanding is the starting point of effective prevention. A weekly indoor and outdoor sweep to empty or cover any water-holding container is far more effective than periodic spraying alone.

Wearing light-coloured, long-sleeved clothing during peak biting hours in the morning and late afternoon adds another layer of protection. Insect repellents containing DEET or Picaridin applied to exposed skin are effective. Mosquito nets, while less critical for a daytime biter, help when napping during the day.

Is There a Dengue Vaccine and Who Should Get It?

A dengue vaccine (Dengvaxia) does exist, but it is not suitable for everyone. The vaccine is approved only for people who have confirmed prior dengue infection on laboratory testing. This restriction is medically important: someone who has never been infected and receives the vaccine may actually face a higher risk of severe dengue if they later encounter the virus naturally.

For this reason, do not seek this vaccine on your own initiative. The decision belongs to your doctor, who knows your infection history. For people without a confirmed prior infection, the primary protection remains mosquito control and personal prevention measures, not the vaccine.

Key Points to Discuss with Your Doctor

A recurring concern in affected communities is whether dengue immunity from one infection protects against future ones. The short answer is that it does not protect broadly. Infection with one of the four dengue serotypes grants lasting immunity only to that specific serotype. Exposure to a different serotype later carries the added risk of a more severe reaction, because the immune response from the first infection can amplify the second one in a process called antibody-dependent enhancement.

Another common misunderstanding is about when to go to the clinic. Many people wait until they feel severely ill before seeking help, reasoning that dengue is just a fever. The right time to see a doctor is early in the illness, before warning signs develop. Blood counts taken on days three or four give your doctor a baseline to track against. If the platelet count is falling and the haematocrit is rising together, admission for intravenous fluids and monitoring is usually recommended even before frank warning signs appear.

For patients managing dengue at home, keeping a simple record of fever readings, fluid intake and any new symptoms each day is practical and genuinely useful. A 2022 survey in Shabwah, Yemen found that community knowledge about dengue danger signs and when to seek care was significantly lacking, and that better patient education reduced delays in reaching appropriate care. Knowing what to watch for is half the battle.

Sources

• Alghazali KA, Teoh BT, Loong SK et al: Dengue Outbreak during Ongoing Civil War, Taiz, Yemen, Emerging infectious diseases, 2019
• Saghir MA, Ahmed WAM, Dhaiban MMA et al: Knowledge, attitude, and practices of the community toward dengue fever in Shabwah Governorate, Yemen: a descriptive study, The Journal of the Egyptian Public Health Association, 2022
• Tejo AM, Hamasaki DT, Menezes LM et al: Severe dengue in the intensive care unit, Journal of intensive medicine, 2024
• Madani TA, Abuelzein el-TM, Al-Bar HM et al: Outbreak of viral hemorrhagic fever caused by dengue virus type 3 in Al-Mukalla, Yemen, BMC infectious diseases, 2013
• Alyousefi TA, Abdul-Ghani R, Mahdy MA et al: A household-based survey of knowledge, attitudes and practices towards dengue fever among local urban communities in Taiz Governorate, Yemen, BMC infectious diseases, 2016
• World Health Organization: Dengue and severe dengue fact sheet