Causes of Dengue Fever
Dengue fever is caused by being bitten by the Aedes mosquito, which is the vector of this disease. If the mosquito bites and draws blood from an infected person and then bites others, it can continuously spread the infection.
There are two types of Aedes mosquitoes that transmit the disease. The first type is the Aedes aegypti, which breeds in stagnant water around homes, such as water puddles, under the legs of cupboards, flower vases, uncovered jars, various containers, and discarded tires that collect rainwater. The second type is the Aedes albopictus, which breeds in gardens, on trees, water puddles, and tree stumps that collect rainwater.
Epidemiologically, breeding sites for mosquito larvae are commonly found in residential areas, including temples and schools.
Dengue Fever is an Endemic Disease and a Long-standing Public Health Problem
Each year, Thailand has tens of thousands of dengue fever cases, with some years reporting over one hundred thousand cases. Most infected individuals are young children and school-aged children. The regions most affected are the South and Central regions, as well as Bangkok, which directly correlates with rainfall and population density. The peak season is from May to September.
Symptoms of the Disease
Dengue infection should be suspected when there is a sudden high fever, severe body aches, especially muscle pain in the back during the first 1-3 days, loss of appetite, and symptoms similar to a general viral infection. However, respiratory symptoms such as cough, sneezing, sore throat, and runny nose are usually “not present”.
Diagnosis
Symptoms during the first 1-3 days are difficult to distinguish from other viral infections. Blood tests may not show clear abnormalities. Doctors may check for easy bleeding by using a blood pressure cuff on the upper arm to see if there are any petechiae. Currently, laboratory diagnostic methods have advanced and can detect dengue infection from blood tests with results available within about 1 hour.
Severity of the Disease
Dengue fever in children is mostly mild, with fever lasting only a few days and recovering on its own.
In adults, severe symptoms may occur, indicated by abdominal pain, vomiting, loss of appetite, extreme fatigue, lethargy, bleeding in various areas such as bleeding gums, nosebleeds, and petechiae on the body.
The severity of the disease is caused by the virus destroying platelets, which are responsible for stopping bleeding, leading to easy bleeding. Petechiae, bleeding gums, nosebleeds, gastrointestinal bleeding, and brain hemorrhages may be observed.
Additionally, the virus causes leakage of fluids outside the blood vessels, reducing blood supply to organs, resulting in fatigue, shortness of breath, lethargy, rapid pulse, and low blood pressure. This is considered severe dengue fever and requires immediate medical treatment.
Reinfection and Disease Severity
Dengue fever has 4 serotypes. Once infected, the body develops immunity to that serotype but can still be infected by other serotypes. Reinfection in individuals with immunity to other serotypes can trigger a severe reaction, making symptoms more severe than the first infection.
The dengue virus can affect multiple body systems. The dangers from the virus arise from direct inflammation of the affected organs and from massive fluid leakage in the body. Besides causing low blood pressure, it also impairs organ function due to insufficient blood supply. Examples of severe complications from dengue virus infection include:
- Infection of the meninges (meningitis)
- Bleeding in various organs such as the gastrointestinal tract and brain
- Shock due to insufficient blood supply to organs
- Respiratory failure from fluid leakage flooding the lungs
- Liver failure caused by the virus itself and from insufficient blood supply
Treatment
- Most dengue infections recover on their own. Adequate rest is essential.
- Minimize medication use. Anti-inflammatory drugs or antibiotics have no effect on treatment.
- If severe symptoms occur, such as lethargy, difficulty breathing, vomiting or bloody stools, severe abdominal pain, seek hospital care immediately.
Precautions
- Pain relievers such as aspirin and NSAIDs like ibuprofen, including combination drugs, are prohibited for dengue treatment.
- Paracetamol should be used only as necessary, such as for high fever or severe pain, because paracetamol can cause liver inflammation, especially in those with pre-existing liver problems.
Dengue Vaccine
The dengue vaccine has been approved for use since 2015 in many countries, including Thailand, a tropical country with a high incidence of dengue fever each year. The vaccine protects against all 4 serotypes of dengue. Its efficacy prevents dengue fever by 65.6%, reduces disease severity by 93.2%, and decreases hospitalization rates by 80.8%.
This vaccine is used for individuals aged 9-45 years and is most effective in those who have previously been infected with dengue, as reinfection tends to be more severe than the first infection.
According to epidemiological statistics, the highest infection group is school-aged children aged 10-14 years, followed by the 5-9 years age group. In Thailand, especially in Bangkok, most people over 15 years old have been infected before, often with no or mild symptoms. Vaccination is therefore recommended for those over 15 years old, especially those with a history of previous infection.
Dr. Phatthaya Riangchan
Infectious Disease Specialist
Internal Medicine Center, Phyathai Nawamin Hospital
