Dengue: What to Know, Watch For and Prevent

Overview

Dengue is a viral illness caused by dengue virus (DENV) and spread mainly by the bite of an infected female Aedes mosquito. It is common in tropical and subtropical places, including the Philippines. Many infections cause no symptoms or only mild illness, but some progress to severe dengue, which can cause shock, serious bleeding, organ impairment, or death. Early recognition and timely medical care matter.

Latest statistics in the Philippines

The latest nationwide figures available for this draft, from Department of Health (DOH) surveillance data covering January 4 to August 1, 2026, recorded 93,155 dengue cases and 386 deaths. That was 46% lower than the 174,077 cases and 699 deaths recorded during the same period in 2025. Central Luzon, the National Capital Region and CALABARZON recorded the highest case totals and several local areas had crossed alert or epidemic thresholds. Dengue is no longer limited to the rainy season: DOH describes it as a year-round concern in the Philippines, although cases often increase during rainy months when standing water creates more mosquito-breeding sites. Surveillance counts can change as late reports are verified.

Cause: the dengue mosquito

The main vector is the female Aedes aegypti mosquito; Aedes albopictus can also spread dengue but is generally a secondary vector. A mosquito becomes infected when it bites a person who has dengue virus in the blood, then can pass the virus to another person through a later bite. Aedes aegypti commonly lives close to people and lays eggs in small water-holding containers around homes, schools, workplaces and other built-up areas.

Aedes aegypti is a daytime feeder. Biting is usually strongest in the early morning and before dusk, but the mosquito can bite at other times, including indoors and on cloudy days.

There are four dengue virus serotypes: DENV-1, DENV-2, DENV-3 and DENV-4. Infection with one serotype usually gives lifelong protection against that same serotype, but only short-lived protection against the other three. This is why a person can have dengue more than once. A second infection with a different serotype carries a higher risk of severe dengue, although severe dengue can happen during a first or any later infection. Symptoms alone cannot tell you which serotype caused an illness or predict your individual risk.

What are the symptoms?

Symptoms usually begin about 4-10 days after infection and last 2-7 days. Many people have no symptoms. When illness occurs, common symptoms include sudden high fever, severe headache, pain behind the eyes, muscle, joint, or bone pain, nausea, vomiting, swollen glands and skin rash.

Diagnosis

A health professional considers symptoms, examination, illness timing, residence and travel history. During the first 0-7 days of illness, usual blood tests include a nucleic acid amplification test (NAAT), such as RT-PCR, together with an IgM antibody test, or an NS1 antigen test together with an IgM test. NAAT or RT-PCR detects viral genetic material; NS1 detects a dengue protein; and IgM suggests a recent infection and becomes more useful several days into illness. After day 7, IgM is the main test and a second sample may be needed. A complete blood count (CBC) is often requested to monitor platelets, hematocrit and other changes, but a CBC alone does not confirm dengue. A negative early test does not always rule out dengue.

Treatment at home and when to seek care

There is no specific antiviral treatment for dengue. If a health professional says home care is appropriate, rest, drink plenty of fluids such as water or electrolyte drinks and use paracetamol (acetaminophen) for fever or pain. Do not take aspirin, ibuprofen, or other nonsteroidal anti-inflammatory drugs because they can increase the risk of bleeding. Do not take antibiotics unless prescribed. Seek medical advice for fever or suspected dengue. Seek immediate consult for severe abdominal pain or tenderness, persistent vomiting, bleeding from the nose or gums, blood in vomit or stool, rapid breathing or difficulty breathing, unusual sleepiness or restlessness, marked weakness, pale or cold skin, or sudden worsening. Warning signs often appear as the fever goes away, during the critical phase, so a person may briefly seem better before becoming seriously ill.

How to prevent dengue

Search for breeding places after rain and as part of a regular household routine. Empty, turn over, scrub, dry, or safely dispose of containers that collect water, such as buckets, vases, plant saucers, bottles, discarded tires, toys, roof gutters and outdoor equipment. Cover water-storage containers tightly, keep drains and surroundings clean and do not overlook small or hidden containers where mosquitoes can lay eggs.

Protect skin from bites with loose, long-sleeved clothing and pants, mosquito repellent lotion applied to exposed skin, window or door screens and mosquito nets for people sleeping during the day.

Vaccination is another preventive measure, but the schedule depends on the product, regulatory approval and prior infection. WHO recommends Qdenga (TAK-003) for children aged 6-16 years in settings with high dengue transmission; it is given as 2 injections at least 3 months apart. In June 2026, the Philippine government reported that the FDA was still reviewing Qdenga, so families should confirm whether it is approved and available locally before vaccination. CDC guidance for Dengvaxia is different: it starts at age 9, requires 3 injections at 0, 6 and 12 months and is limited to children aged 9-16 years in endemic areas with laboratory-confirmed previous dengue infection.

For more information, coordinate with your barangay health center or primary care physician.

What are the DOH and Philippine government campaigns and programs?

The DOH 4S strategy means Search and destroy mosquito-breeding places, use Self-protection measures, Seek early consultation and Support fogging or spraying only in hotspot or outbreak areas. The related Alas Kwatro Kontra Mosquito or 4 O'Clock Habit turns a daily 4:00 PM check into a community routine: Taob (flip), Taktak (shake out), Tuyo (dry) and Takip (cover) water-holding containers.

The DOH's National Aedes-Borne Viral Diseases Prevention and Control Program supports surveillance, community education, health-worker capacity, access to diagnosis and care, outbreak response and integrated mosquito control for dengue and other Aedes-borne diseases. DOH centers and local governments also mark Dengue Awareness Month every June, observe ASEAN Dengue Day, work with schools and barangay health workers and coordinate local cleanup and response activities.

Summary

Dengue can occur throughout the year in the Philippines and is spread mainly by infected female Aedes mosquitoes, which bite most strongly in the early morning and before dusk. The four dengue serotypes mean a person can have dengue more than once; infection with one serotype usually gives lifelong protection against that same serotype, while infection with a different serotype carries a higher risk of severe dengue. Fever, headache, body pain, nausea, vomiting and rash should be assessed by a health professional. Mild illness may be managed with rest, fluids and paracetamol, while aspirin and ibuprofen should be avoided. Seek immediate consult when warning signs appear, especially as the fever falls. Remove standing water, use mosquito repellent lotion and protective clothing and follow the DOH 4S and 4 O'Clock Habit guidance. Vaccination against Dengue is also considered a preventive measure.