Dengue fever is an acute infectious disease caused by a mosquito-borne virus, primarily transmitted through the bites of infected mosquitoes. This viral illness is widespread in tropical and subtropical regions worldwide, especially during the rainy season or in hot, humid environments where outbreaks are more common. According to the World Health Organization, approximately 100 million people are infected annually, with case numbers increasing year by year.
The virus is transmitted through the bites of Aedes aegypti and Aedes albopictus mosquitoes. Humans infected with the virus may exhibit various clinical symptoms, and severe cases can lead to hemorrhagic phenomena or shock syndrome. Although the majority of patients experience mild symptoms, the mortality rate in severe cases can exceed 20%, making this disease a significant public health concern.
The pathogen responsible for dengue fever is the dengue virus, which has four serotypes numbered 1 to 4. The virus replicates within the mosquito vector, and when the mosquito bites a human, the virus enters the bloodstream. After an incubation period of 7-10 days within the mosquito, the mosquito becomes capable of transmission. This biological characteristic makes controlling outbreaks challenging, as mosquitoes can serve as long-term carriers of the virus.
Risk factors are mainly related to geographic environment and individual behaviors. Living in or traveling to endemic areas, lacking mosquito prevention measures, and residing in environments with stagnant water (such as flower vases or discarded containers) increase infection risk. Immunocompromised individuals (such as children and the elderly) or those previously infected with other dengue serotypes may develop more severe hemorrhagic dengue upon reinfection with a different serotype.
The incubation period after infection is typically 3-14 days, followed by an acute febrile phase. Typical symptoms include high fever (39-40°C), severe headache, retro-orbital pain, muscle pain, and rash. About 5%-20% of patients develop the "dengue symptom complex," which may include lymphadenopathy and leukopenia.
A small number of cases progress to severe dengue, characterized by bleeding tendencies (such as gum bleeding, petechiae), hypotension, and signs of organ hypoperfusion or shock. This progression often occurs after the fifth day of fever, known as the "critical phase," during which viremia subsides but immune overreaction causes increased vascular permeability.
According to WHO classification, symptoms are categorized as:
Clinical diagnosis primarily relies on symptom assessment and epidemiological history, including recent mosquito bites and travel to endemic areas. Laboratory tests include complete blood count (noting thrombocytopenia), viral RNA detection, and antibody testing. During the acute phase, NS1 antigen detection allows early diagnosis, while serum antibody tests (IgM/IgG) confirm infection during recovery.
Differential diagnosis should exclude other febrile illnesses such as influenza, malaria, or infections with chikungunya virus. During outbreaks, rapid antigen tests can effectively screen suspected cases on-site, but definitive diagnosis requires laboratory confirmation.
The diagnostic process usually includes:
Currently, there are no specific antiviral drugs available; treatment is mainly supportive. Patients with high fever should undergo physical cooling and fluid replacement. Severe dehydration requires intravenous fluids to maintain blood volume. Pain management uses acetaminophen; non-steroidal anti-inflammatory drugs are avoided due to potential bleeding risk.
Severe cases require intensive care monitoring of blood pressure and organ function, with possible transfusions of platelets or fresh frozen plasma. Emerging therapies include the use of monoclonal antibodies (such as Tocilizumab) in experimental treatments for cytokine storms, though these are not yet widely adopted. The traditional antiviral drug Takhminavir is currently in phase III clinical trials.
Principles of treatment include:
Prevention strategies mainly focus on interrupting the mosquito transmission cycle. Environmental control includes removing stagnant water containers, using insecticides on water storage facilities, and regular fogging in high-risk areas. Personal protection involves wearing long-sleeved clothing, applying DEET-based repellents, and using bed nets indoors.
Regarding vaccination, the tetravalent dengue vaccine (TDV) has been approved in multiple countries. However, vaccination eligibility is limited by age and vaccine efficacy varies by serotype. It is recommended that individuals undergo medical assessment of their infection history and immune status before vaccination to avoid antibody-dependent enhancement (ADE) that could worsen disease severity.
Community control measures include:
If you experience the following symptoms, seek medical attention immediately: high fever lasting more than three days, unexplained bruising or petechiae, persistent vomiting, worsening abdominal pain, shortness of breath, or altered consciousness. These signs may indicate progression to hemorrhagic phase or pre-shock stage.
Individuals previously infected with dengue should be vigilant for symptom changes upon reinfection with a different serotype. Pregnant women and those with chronic illnesses should seek early medical assessment even with mild symptoms. During outbreaks, the presence of the classic "three reds" (facial flushing, conjunctival injection, neck flushing) should be considered high-risk signs.
The following conditions require urgent hospitalization:
Dengue symptoms such as fever, headache, muscle pain, and malaise are similar to those of a cold, but dengue often includes retro-orbital pain, skin rash, and severe joint pain (commonly called "breakbone fever"). If high fever persists for more than three days, with frequent vomiting or skin bleeding, immediate medical attention is necessary. These are warning signs that differentiate dengue from a common cold.
What dietary or activity restrictions are recommended during recovery from dengue fever?During recovery, avoid strenuous activities as the virus may affect platelet counts, and vigorous exercise could increase bleeding risk. Dietary recommendations include easily digestible foods such as rice porridge and vegetable soups, along with adequate hydration and electrolyte intake. Alcohol and spicy foods should be avoided to reduce liver burden.
Does previous dengue infection confer immunity to other serotypes?Infection with one dengue serotype provides immunity to that specific serotype, but reinfection with a different serotype can lead to more severe disease due to antibody-dependent enhancement (ADE). Therefore, even individuals with prior infection should continue to take precautions against mosquito bites.
How can residents in dengue-endemic areas reduce mosquito breeding around their homes?Key measures include removing stagnant water containers such as flower vases and discarded cans, as Aedes larvae breed in clean water. Using window screens, bed nets, and DEET-based repellents can enhance personal protection. Community efforts should include regular fogging and maintaining dry environments to break the mosquito lifecycle.
How long after symptom resolution can dengue patients resume normal activities?Mild cases typically recover gradually within 1-2 weeks, but some patients may need longer due to immune system impairment. It is advisable to avoid strenuous activities for about one month post-recovery and to have regular follow-up blood tests for platelet counts. Patients who experienced bleeding or shock should follow medical advice to extend rest periods accordingly.
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