The Three Phases of Dengue Fever

In this article:

• Dengue season in the Philippines
• Known dengue hotspots as of February 2025
• How to spot dengue symptoms
• What to do if you suspect dengue
• How is dengue diagnosed
• The three phases of dengue fever
• Critical complications of severe dengue
• How is dengue fever treated?
• Can you get dengue again?
• How to prevent dengue
• Protect your loved ones from life's surprises

Dengue season in the Philippines

Dengue fever is caused by the dengue virus, which is spread to humans through the bites of infected Aedes mosquitoes, particularly Aedes aegypti and Aedes albopictus. These mosquitoes are common in tropical and subtropical areas worldwide, such as Southeast Asia, the Pacific Islands, the Caribbean, and Latin America. The dengue virus is part of the Flavivirus genus and has four different types (DENV-1, DENV-2, DENV-3, and DENV-4). When a mosquito bites someone who is already infected with the dengue virus, it becomes a carrier and can then pass the virus to other people through its bites. This transmission cycle is supported by the mosquitoes' breeding habits, which often involve stagnant water found in containers, old tires, and other common places near human dwellings.

In 2024, the country recorded 208,000 dengue cases by September, marking a 68% increase compared to the previous year. This rise in cases is attributed to the proliferation of mosquito breeding sites due to increased rainfall and stagnant water.^[1]

Dengue hotspots in the Philippines (February 2025)

As of February 2025, the Department of Health (DOH) identified several dengue hotspots across the country. These regions have reported significant increases in dengue cases, prompting local governments to intensify their anti-dengue campaigns. ^[2]

These include:

• Calabarzon (Cavite, Laguna, Batangas, Rizal, and Quezon)
• Metro Manila
• Central Luzon

How to spot dengue symptoms

Recognizing the symptoms of dengue fever early is crucial for effective treatment and management. Here are the common symptoms in more detail:

1. High fever
   
   Dengue fever typically begins with a sudden onset of high fever, often reaching up to 40°C (104°F). The high fever is usually one of the first symptoms to appear and can last for 2-7 days. It is often accompanied by chills and sweating.
   
   
2. Severe headache
   
   Intense pain, particularly behind the eyes (retro-orbital pain). This headache is often described as throbbing and can be debilitating, making it difficult for the patient to perform daily activities.
   
   
3. Joint and muscle pain
   
   Severe pain in muscles and joints, sometimes referred to as "breakbone fever" due to the intensity of the pain. This symptom can cause significant discomfort and may be accompanied by muscle weakness and stiffness.
   
   
4. Nausea and vomiting
   
   Frequent episodes of nausea and vomiting. These gastrointestinal symptoms can lead to dehydration, which is particularly dangerous in dengue patients. It's important to maintain fluid intake.
   
   
5. Rash
   
   A rash that may appear a few days after the fever starts. It can be maculopapular (flat and raised areas) or petechial (small red or purple spots caused by bleeding under the skin). The rash can be itchy and may spread across the body. It often appears on the chest, back, and limbs.
   
   
6. Mild bleeding
   
   Symptoms such as nosebleeds, gum bleeding, or easy bruising.These mild hemorrhagic manifestations indicate that the dengue virus is affecting the blood's ability to clot. It's important to monitor for any signs of more severe bleeding. ^[3]

Early detection and management of these symptoms can help prevent the progression to severe dengue, which can be life-threatening. If you or someone you know exhibits these symptoms, it's essential to seek medical attention promptly.

What to do if you suspect dengue

If you suspect dengue fever, it is essential to:

• Seek Medical Attention: Visit a healthcare provider for proper diagnosis and treatment.
• Stay Hydrated: Drink plenty of fluids to prevent dehydration.
• Rest: Ensure adequate rest to help your body recover.
• Monitor Symptoms: Keep an eye on symptoms, especially warning signs of severe dengue, such as severe abdominal pain, persistent vomiting, and bleeding. ^[3]
  

How is dengue diagnosed

Dengue fever is diagnosed through a combination of clinical evaluation and laboratory tests. Here are the primary methods used:

1. Clinical Evaluation
   Medical History - Doctors review the patient's medical history, including recent travel to areas with dengue outbreaks.
   Symptom Check - Common symptoms like high fever, severe headache, retro-orbital pain, muscle and joint pain, rash, and mild bleeding are assessed.
2. Laboratory Tests
   Nucleic Acid Amplification Test (NAAT) - This test, such as RT-PCR, detects the genetic material of the dengue virus. It is highly specific and can identify the virus within the first 7 days of symptoms.
   NS1 Antigen Test - The NS1 ELISA test detects the non-structural protein 1 of the dengue virus in the blood during the acute phase (first 7 days). A positive result indicates a current or recent infection.
   IgM Antibody Test - This test detects IgM antibodies against the dengue virus, which appear about 4-5 days after symptom onset and can remain detectable for up to 12 weeks. It is used in combination with NAAT or NS1 tests for a more accurate diagnosis.
3. Serologic Tests:
   IgM Antibody Capture ELISA (MAC-ELISA) - This test captures human IgM antibodies and uses dengue virus antigens to detect the presence of dengue-specific antibodies. It is useful for diagnosing dengue in the later stages of the illness.
4. Convalescent Phase Testing
   If initial tests are negative, a second sample may be collected after 7 days to check for IgM antibodies. A change from negative to positive results in paired samples confirms a current dengue infection.

These diagnostic methods help healthcare providers confirm dengue fever and differentiate it from other illnesses with similar symptoms. If you suspect dengue, it's crucial to seek medical attention promptly for proper diagnosis and treatment. ^[7]

The three phases of dengue fever

Dengue fever goes through three main stages, each with different symptoms:

1. Febrile Phase

• • Duration: 2-7 days
  • Symptoms: This stage starts with a sudden high fever, often reaching 40°C (104°F). You might also have severe headaches, muscle and joint pain (sometimes called "breakbone fever"), nausea, vomiting, and a rash. Minor bleeding, like small red spots on the skin (petechiae) or bleeding gum, can also happen.

  • Note: This is the most uncomfortable phase, but it's also when the virus is easiest to detect in the blood.

2. Critical Phase

• • Duration: 24-48 hours
  • Symptoms: This stage usually begins when the fever goes down. You might experience severe abdominal pain, constant vomiting, fluid buildup in the body, bleeding from the mouth or nose, extreme tiredness, and restlessness. This phase is dangerous because fluid can leak from blood vessels, leading to shock and other serious problems.
  • Note: Close monitoring is crucial during this phase to catch any severe symptoms early.

3. Recovery Phase

• • Duration: Several days
  • Symptoms: In this stage, the body starts to reabsorb the leaked fluids, and vital signs stabilize. You will start to feel better, but you might still feel very tired and weak as you recover.
  • Note: Even though you feel better, it's important to keep an eye on your health and follow up with your doctor. ^[4]

Complications of dengue fever

Severe dengue can lead to serious, life-threatening issues, including:

• Severe bleeding: Internal bleeding that can be fatal if not treated promptly.
• Organ Impairment: Problems with the liver, heart, or brain.
• Shock: Caused by significant fluid leakage, leading to circulatory failure and potentially death.

Understanding these phases and symptoms can help in early detection and effective management of dengue fever, reducing the risk of severe complications. ^[4]

How is dengue fever treated?

Dengue fever treatment primarily focuses on managing symptoms and preventing complications, as there is no specific antiviral treatment for the dengue virus. Here are the key aspects of dengue fever treatment:

1. Symptomatic treatment

• • Fever and pain management - The primary approach to managing dengue fever involves controlling fever and alleviating pain. Acetaminophen (Tylenol) is commonly recommended to reduce fever and relieve muscle and joint pain. It's important to avoid non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin, ibuprofen (Advil, Motrin), and naproxen (Aleve) as they can increase the risk of bleeding complications.^[6]
  • Hydration - Maintaining adequate fluid intake is crucial to prevent dehydration, which can occur due to high fever, vomiting, and reduced fluid intake. Oral rehydration solutions (ORS), electrolyte drinks, and plenty of water are recommended. ^[6]

2. Monitoring and supportive care

• • Regular Monitoring - Patients with dengue fever should be closely monitored for signs of severe dengue, especially during the critical phase (days 3-7 of illness). This includes checking for warning signs such as severe abdominal pain, persistent vomiting, rapid breathing, bleeding, and changes in mental status.^[10]
  • Hospitalization - Severe cases of dengue may require hospitalization for intensive monitoring and supportive care. This includes intravenous (IV) fluid and electrolyte replacement to manage dehydration and maintain blood pressure.^[6]

3. Management of severe dengue

• • Fluid management - In severe dengue, careful management of fluids is essential to prevent shock and organ failure. IV fluids are administered to maintain adequate blood volume and prevent plasma leakage.^[10]
  • Blood transfusion – In cases of severe bleeding or significant blood loss, blood transfusions may be necessary to replace lost blood and improve oxygen delivery to tissues.
  • Intensive care – Patients with severe dengue may require admission to an intensive care unit (ICU) for close observation and management of complications such as severe bleeding, organ impairment, and shock.^[5]

4. Preventing further transmission

• • Mosquito control - Patients with dengue fever should take measures to avoid mosquito bites to prevent further transmission of the virus. This includes using insect repellent, sleeping under mosquito nets, and staying in well-screened or air-conditioned rooms.^[6]

5. Follow-up care

• • Recovery monitoring - After the acute phase of dengue fever, patients should continue to be monitored for any lingering symptoms or complications. Follow-up visits with healthcare providers are important to ensure complete recovery. ^[5]

By focusing on these treatment strategies, healthcare providers can effectively manage dengue fever and reduce the risk of severe complications. Early detection and prompt medical attention are crucial for a positive outcome.

Can you get dengue again?

Yes, it is possible to get dengue more than once. There are four different serotypes of the dengue virus (DENV-1, DENV-2, DENV-3, and DENV-4). Infection with one serotype provides lifelong immunity to that specific serotype but not to the others. Subsequent infections with different serotypes increase the risk of severe dengue due to a phenomenon known as antibody-dependent enhancement (ADE).

Individuals who contract dengue for a second time face a higher risk of developing severe dengue. Severe dengue symptoms typically emerge after the initial fever subsides and may include:

• Severe abdominal pain
• Persistent vomiting
• Rapid breathing
• Bleeding gums or nose
• Fatigue
• Restlessness
• Blood in vomit or stool
• Intense thirst
• Pale and cold skin
• Weakness

If you notice any of these symptoms, it's crucial to seek medical attention immediately. [8]

How to prevent dengue

Preventing dengue fever primarily involves reducing exposure to mosquitoes and eliminating their breeding sites. Here are some detailed steps to help you avoid dengue:

1. Use insect repellent
   
   DEET-based repellents, along with natural alternatives like oil of lemon eucalyptus, can keep mosquitoes at bay. Be sure to reapply after being in contact with water, like after swimming or sweating.
   
   
2. Wear protective clothing
   
   Cover up! Long sleeves and pants are simple but effective ways to reduce exposure, especially for the little ones. Opt for light-colored clothing, as mosquitoes are attracted to dark colors. Dengue-spreading mosquitoes bite during the day. So, if your child must be outside, keep them as cool and hydrated as possible.
   
3. Use mosquito nets
   
   This may also be a great time to bring out the old-school kulambo, which really is great protection against mosquitoes. Use mosquito nets over beds, especially if you sleep during the day or live in areas with high mosquito activity.
   
   
4. Eliminate breeding sites
   
   Dengue-prone water isn’t just in canals and other drainage systems. Mosquitoes also inhabit other “clean” water areas like your ornamental planters and garden fountains.But there’s no need to feel paranoid. Just regularly check your home and surroundings for containers collecting water, from indoor flower vases to water pails, old tires or unused plant pots. If you cannot empty them, change the water frequently, clean thoroughly and keep them tightly covered.
   
   
5. Install Screens:
   
   Install screens on windows and doors to keep mosquitoes out of your home. Regularly check and repair any holes or tears in screens to maintain their effectiveness.

By following these preventive measures, you can significantly reduce the risk of dengue fever and protect yourself and your family from this potentially serious illness. [9]

Protect your loved ones from life's surprises

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