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What is Dengue Fever?

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Dengue fever is an infectious tropical disease caused by the dengue virus transmitted by Aedes mosquitoes. It can progress to more a deadly form of the disease known as dengue haemorrhagic fever and cause death, and they infect 50 million people a year.

An estimated 500,000 people with severe dengue require hospitalization each year, and with an estimated 2.5% case fatality, annually (source: WHO).

Thailand’s rainy season, running from May through September, is also the high risk period for dengue fever, a potentially serious condition most prevalent in tropical countries, but particularly in Northeastern of Thailand.

Thailand has reported large numbers of Dengue cases nationally. Cases have been reported in Bangkok, Nakhonratchasima, Ubonratchathani, Nakhonsrithammarat, Chonburi, Srisaket, Songkhla, Burirum and Nakhonpathom.

Division of Vector-Borne Diseases, Ministry of Public Health, Dengue Fever Situation in Thailand from 1 January - 15 August 2025, there were 36,439 dengue fever patients and 33 deaths (see updated dengue fever situation report here).

Dengue Symptoms

  • Sudden onset of continuous high fever

  • Red rashes on skin

  • Acute pain at the bones, muscles, joints, eye-balls and head

  • Loss of appetite

  • Vomiting and nausea

  • Bleeding from nose, gums and skin

Dengue Treatment

Vaccine tests are still carried out and there is no specific treatment for dengue, but appropriate medical care frequently saves the lives of patients with the more serious dengue haemorrhagic fever. See a doctor immediately for diagnosis and treatment if you experience symptoms of dengue fever.

Dengue Fever Symptoms in Children

  • High Fever: Persistent high fever (38-40°C or 100.4-104°F) lasting 2-7 days, often without a runny nose or cough, distinguishing it from common colds.

  • Fatigue and Irritability: Children may appear more fatigued, less playful, and have a decreased appetite.
  • Frequent Vomiting: Especially after eating or drinking.
  • Abdominal Pain: A specific pain below the right ribcage due to an enlarged liver.
  • Skin Rash: Small, red spots or patches resembling measles rash that can appear all over the body.
  • Bleeding Symptoms: Easy bruising, nosebleeds, bleeding gums, or black, tarry stools. This could indicate severe dengue.
  • Other Symptoms: Headache, muscle pain, flushed face, and red eyes can also be present.

It is important for caregivers and health professionals to recognize these symptoms and seek medical attention promptly if dengue fever is suspected, as early diagnosis and appropriate treatment can significantly improve outcomes.

The Severity of Dengue Fever in Children

The severity of dengue fever in children refers to the range of symptoms and complications that can occur as a result of the infection. Children are at a higher risk of severe dengue compared to adults because their immune systems are not yet fully developed, and young children may not be able to clearly communicate their symptoms, making it harder for parents to detect the disease early.

The World Health Organization (WHO) classifies dengue fever severity into three levels:

  1. Dengue Fever:
    • High fever
    • Headache
    • Muscle and joint pain
    • Skin rash
    • No bleeding complications
  2. Dengue Hemorrhagic Fever:
    • Similar symptoms to dengue fever
    • Bleeding manifestations, such as nosebleeds, petechiae (red spots on the skin), black stools, or vomiting blood
  3. Dengue Shock Syndrome:
    • Severe complication
    • Signs of shock, such as cold hands and feet, rapid pulse, low blood pressure, and lethargy

Risk factors for severe dengue include:

  • Age: Younger children, especially those under one year old, are at a higher risk.
  • Previous dengue infection: If a child has had one dengue infection before and gets infected again with a different dengue virus serotype, the risk of severe symptoms increases.
  • Underlying health conditions: Conditions like heart disease, diabetes, blood disorders, or malnutrition can also increase the severity of dengue fever.

Possible complications in children can include bleeding (e.g., gastrointestinal bleeding, bleeding in the brain), shock due to plasma leakage, liver failure, brain inflammation, and kidney failure.

Prevention is crucial, including measures such as eliminating mosquito breeding sites, using mosquito repellents, sleeping under mosquito nets, and considering dengue vaccination when eligible.

Parents should be vigilant for warning signs in young children, such as excessive crying, high-pitched crying, extreme lethargy, not playing, difficulty drinking milk, or frequent vomiting after feeding. If a child shows these symptoms, it’s important to seek medical attention immediately to prevent the disease from worsening, which could be life-threatening.

Managing Dengue Fever Symptoms in Children

The goal of managing dengue fever symptoms in children is to provide supportive care, reduce the severity of symptoms, and prevent complications. This can be done both at home and in the hospital, depending on the severity of the condition.

Home Care for Children with Dengue Fever:

  1. Physical Comfort:
    • Sponging: Use a clean cloth soaked in lukewarm or cool water to sponge the child, focusing on areas like the neck, armpits, and groin to help reduce fever. Avoid chilling the child.
    • Change Clothing: Make sure the child wears dry clothes to avoid chills and discomfort.
    • Avoid Aspirin and Ibuprofen: Do not give aspirin or ibuprofen, as these can increase the risk of bleeding. Instead, use acetaminophen (paracetamol) as directed by a doctor to manage fever.
    • Hydration: Ensure the child drinks plenty of clean water to prevent dehydration. If the child is not drinking enough, offer small, frequent sips of water or oral rehydration solutions.
    • Nutritional Care: Feed the child easily digestible foods such as rice porridge, congee, bland soups, and fruits. Avoid spicy or acidic foods that may irritate the stomach.
    • Rest: Ensure adequate rest in a well-ventilated, mosquito-free environment.
  2. Monitoring Symptoms:
    • Keep a close watch on the child’s symptoms, including fever, rash, vomiting, and bowel movements. If the symptoms worsen or if the child shows signs of dehydration (such as dry mouth, no tears when crying, sunken eyes), seek medical attention immediately.
  3. Preventing Complications:
    • Make sure the living environment is free from mosquito exposure. Use mosquito nets and repellents to prevent further bites.
    • Maintain a clean and well-ventilated living space to reduce the risk of attracting mosquitoes.

If the child’s symptoms worsen or if any alarming signs such as increased irritability, persistent vomiting, or bleeding are observed, it is crucial to consult a healthcare professional promptly to prevent complications and ensure appropriate treatment.

Dengue Fever During Pregnancy: A Silent Threat That Expectant Mothers Must Watch Out For

Pregnancy is a crucial time for expecting mothers to take extra care of their health. However, during the rainy season, a silent threat like dengue fever can lurk, transmitted by mosquitoes such as the Aedes mosquito, posing risks to both mother and baby. Dengue fever in pregnant women is more dangerous than in the general population, as it can lead to severe complications like premature birth or low birth weight for the baby.

Impact on the Fetus:

The impact on the fetus is one of the significant risks for pregnant women with dengue fever. If a mother contracts dengue fever, the dengue virus can cross the placenta to the fetus. This can result in various complications such as:

  • Neonatal dengue infection: The baby may contract the dengue virus either in the womb or during delivery, leading to dengue symptoms after birth, which can be severe.
  • Complications: Dengue fever may cause complications like infections and abnormal bleeding, potentially leading to premature labor. Additionally, the virus can affect fetal growth, resulting in a lower birth weight compared to normal.

The most severe outcomes could be fetal death if dengue fever is severe enough, and conditions like low platelet count and abnormal bleeding could occur, increasing risks such as brain hemorrhage.

Risk Factors:

The risk of fetal complications is higher if a mother contracts dengue fever in the third trimester of pregnancy (28 weeks onwards), as this is a critical period for fetal growth and nearing the time of birth.

Management:

Managing dengue fever in pregnant women requires special precautions to ensure the safety of both the mother and the baby. The treatment is similar to the general population but with added considerations.

  1. Seek Immediate Medical Attention: If dengue fever is suspected, pregnant women should not self-medicate and visit a doctor right away. Avoid taking aspirin or ibuprofen, as these drugs can harm the fetus.
  2. Rest: Ensure ample rest and sleep in a well-ventilated, mosquito-free environment.
  3. Hydration: Drink plenty of clean water to prevent dehydration, which can negatively affect fetal health.
  4. Fever Management: Use a lukewarm water sponge bath to reduce fever. Change the clothes to keep the body dry and avoid chills.
  5. Nutritional Care: Provide easy-to-digest, light foods like rice porridge, congee, soups, and fruits. Follow the doctor’s instructions regarding medications to be taken during this period.
  6. Close Monitoring: Observe for any abnormal symptoms such as high fever, bleeding, or abdominal pain. Attend all doctor appointments to monitor for complications like bleeding or shock, which could endanger both mother and baby.
  7. Mental Health: Take care of mental well-being. Relax, manage stress, and communicate with close friends or family to support mental health.

It's crucial for expecting mothers to remain vigilant and take preventive measures to reduce the risk of contracting dengue fever and to seek medical advice promptly if symptoms appear.

High-Risk Groups for Dengue Fever

While Aedes mosquitoes can bite anyone regardless of age or gender, not everyone is equally affected by dengue fever. Some individuals may experience mild symptoms, while others may suffer severe complications that could be life-threatening.

Elderly

Elderly individuals are a high-risk group for dengue fever, as they are more likely to experience severe symptoms and complications. Aging reduces the immune system's efficiency, making it harder for the body to combat infections, including dengue fever. Additionally, older adults often have pre-existing health conditions like diabetes, hypertension, and heart disease, which can further weaken their immune system and increase the risk of severe complications such as bleeding, organ failure, and even death.

  • Common Health Issues: The presence of chronic conditions like diabetes, hypertension, or heart disease can make elderly individuals more susceptible to complications from dengue fever. They may also struggle with cognitive issues or communication difficulties, which could delay medical attention.

Individuals with Pre-existing Medical Conditions

People with pre-existing medical conditions are at higher risk for severe dengue fever complications. Some of these conditions include:

  • Diabetes: High blood sugar levels can impair immune function, making it harder for the body to fend off the dengue virus, increasing the severity of symptoms and complications.
  • Hypertension: Dengue fever can elevate blood pressure further, increasing the risk of conditions such as brain hemorrhage.
  • Heart Disease: Dengue fever can put additional stress on the heart, potentially leading to heart failure.

Other High-Risk Groups

Several other groups are also at an elevated risk for severe dengue fever:

  • Immunocompromised Individuals:
    • HIV-infected individuals: The virus can damage white blood cells, essential for immune defense, making them more susceptible to severe dengue fever.
    • People on immunosuppressive medications (e.g., organ transplant recipients, autoimmune disease patients) have weakened immune systems that cannot effectively combat infections like dengue fever.
    • Individuals with congenital immune deficiencies: These individuals are born with compromised immune systems and are unable to effectively fight off infections, including dengue fever.
  • Cancer Patients Receiving Chemotherapy: Chemotherapy affects bone marrow function, reducing the production of platelets and white blood cells, which makes chemotherapy patients more susceptible to severe bleeding complications from dengue fever.
  • Obese Individuals: Obesity is associated with chronic inflammation and immune dysfunction, which can exacerbate the severity of dengue fever symptoms.
  • Travelers to Endemic Areas: People traveling to regions with ongoing dengue outbreaks are at a higher risk of contracting the virus, especially if they have not previously been infected. This group includes tourists and travelers who might be unfamiliar with local disease risks.

How Dengue Fever is Diagnosed Accurately

Having a high fever, headache, and body aches doesn't necessarily mean someone has dengue fever. These symptoms can be indicative of other illnesses as well. Therefore, accurate diagnosis is crucial to ensure appropriate treatment and to prevent complications that could be dangerous.

Methods for Diagnosing Dengue Fever

Accurate diagnosis of dengue fever is essential to ensure that patients receive proper, timely treatment and to prevent complications that could be life-threatening. Physicians use several methods to diagnose dengue fever:

1. Medical History

  • Symptoms: The doctor will inquire about symptoms such as high fever, headache, muscle pain, bleeding symptoms, and recent travel history.
  • Previous Illness: If the patient has had dengue fever before or if there is a history of similar illness within the family.
  • Contact with Infected Individuals: The doctor may ask if there have been any close contacts who were diagnosed with dengue fever.
  • Travel History: The doctor will inquire about recent travel to areas with active dengue outbreaks.

2. Physical Examination

  • Vital Signs: The doctor will check for fever, look for signs of dehydration (e.g., dry mouth, low urine output), and assess blood pressure.
  • Physical Signs: The doctor may inspect for rash, check the liver (hepatomegaly), spleen (splenomegaly), and monitor for signs of abdominal pain or swelling.
  • Tourniquet Test: This test helps assess the bleeding tendency by wrapping a blood pressure cuff around the upper arm for five minutes to see if small blood vessels rupture, which is common in dengue fever.

3. Laboratory Tests

  • Blood Tests:
    • NS1 Antigen: This protein from the dengue virus can be detected in the blood during the first week of illness (days 1-9) and is a rapid indicator.
    • IgM Antibody: Appears 5-7 days after symptoms begin and helps confirm acute infection.
    • IgG Antibody: Indicates a previous dengue infection and is detected 14 days post-symptoms.
    • Complete Blood Count (CBC): This will check for reduced red blood cells, white blood cells, and platelets, which often occur in dengue fever.
    • Hematocrit (Hct): Elevated hematocrit levels indicate dehydration, which is common in dengue fever.
  • Urine Test: To check for protein leakage in the urine, which may indicate kidney complications.

Importance of Accurate and Timely Diagnosis

An accurate and timely diagnosis of dengue fever is critical because:

  • Ensures Appropriate Treatment: Dengue fever has no specific antiviral treatment, so care is supportive—mainly fluid management and monitoring for complications.
  • Prevents Complications: Timely diagnosis allows for early intervention to manage severe complications such as bleeding, shock, or organ failure.
  • Reduces Mortality Rates: Delayed diagnosis can lead to serious complications and increase the risk of death.
  • Prevents Outbreaks: Accurate diagnosis helps isolate infected patients and control the spread within communities.
  • Alleviates Anxiety: Quick diagnosis reduces anxiety for both patients and families, providing reassurance and proper management.

Dengue Fever Can Be Prevented: It Starts with You

Dengue fever is a close-to-home threat carried by the Aedes aegypti mosquito. Although there is no 100% vaccine to prevent it, we can reduce the risk of infection and protect ourselves through simple, proactive measures.

Start by Managing Your Environment with the 3 Clean-Up Policy

Mosquitoes, particularly Aedes mosquitoes, are carriers of harmful diseases like dengue fever, Zika, and chikungunya—health threats that are especially concerning during rainy seasons when mosquito populations increase. The 3 Clean-Up Policy is an effective strategy to prevent these diseases:

1. Clean Up Your Home

  • Organize Your Space: Keep your home neat and tidy. Ensure good ventilation and avoid clutter where mosquitoes can hide.
  • Store Clothes Properly: Keep clothing stored away and avoid leaving them hanging around.
  • Clean Regularly: Sweep, mop, and dust your floors regularly to remove dust and debris that can attract mosquitoes.

2. Clean Up Your Waste

  • Dispose of Trash Properly: Get rid of food scraps, fallen leaves, and unused containers around the house. Place trash in closed bins.
  • Avoid Draining Wastewater: Don’t discard waste in drains as it can serve as a breeding ground for mosquitoes.

3. Clean Up Water Sources

  • Cover Water Containers: Ensure all water containers like water barrels, jars, or flower vases are tightly covered.
  • Change Water Weekly: Regularly replace the water in dishes under plants, flower vases, and other containers.
  • Check for Water Stagnation: Regularly inspect old tires, coconut shells, or any items that can hold water and remove them or store them properly.

Vaccination as a Supplementary Prevention Tool

While eliminating mosquitoes is crucial in dengue fever prevention, there is now a dengue fever vaccine available to enhance immunity. This vaccine works by incorporating all four dengue virus strains in a weakened form, which stimulates the body to produce antibodies. These antibodies help prevent the disease or lessen its severity, thereby reducing the risk of complications like bleeding or shock that can be life-threatening and shortening hospital stays.

Who Should Get Vaccinated?

The vaccine is recommended for individuals aged 9-45 years who:

  • Have previously been infected with the dengue virus (confirmed via a blood test).
  • Are healthy without contraindications for vaccination (e.g., allergies to vaccine components).

Before deciding to get vaccinated, it’s advisable to consult a doctor to assess the risks and benefits.

Note: Although the dengue fever vaccine is an important tool, it’s not the only solution. It’s essential to maintain health, control mosquito breeding grounds, and use preventive measures against mosquito bites alongside vaccination.

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