Dengue and Severe Dengue: A Comprehensive Overview
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| A child with a fever |
Key Facts
Dengue is a viral infection spread to humans through the bite of infected mosquitoes.
Around half of the world's population is at risk, with an estimated 100–400 million infections occurring annually.
It is prevalent in tropical and subtropical regions, mainly in urban and semi-urban areas.
While many infections are mild or asymptomatic, severe cases can be life-threatening.
Prevention focuses on mosquito control, as there is no specific treatment for dengue. Early detection and proper medical care significantly reduce fatality rates.
Overview
Dengue, commonly known as "break-bone fever," is a mosquito-borne viral infection. It is widespread in tropical and subtropical climates worldwide.
Most people infected with dengue do not exhibit symptoms. Those who do may experience high fever, headache, body aches, nausea, and skin rashes. Recovery usually occurs within 1–2 weeks. However, some cases progress to severe dengue, requiring hospitalization.
In extreme cases, dengue can be fatal. The best preventive measure is avoiding mosquito bites, particularly during the day.
There is no specific antiviral treatment for dengue. Treatment focuses on symptom relief, mainly with pain relievers.
Symptoms
Dengue symptoms typically appear 4–10 days after infection and persist for about a week. Common symptoms include:
- High fever (40°C/104°F)
- Severe headache
- Pain behind the eyes
- Muscle and joint pain
- Nausea and vomiting
- Swollen glands
- Skin rash
Those infected for the second time are at a higher risk of severe dengue, which manifests after the fever subsides. Symptoms of severe dengue include:
- Severe abdominal pain
- Persistent vomiting
- Rapid breathing
- Bleeding gums or nose
- Fatigue and restlessness
- Blood in vomit or stool
- Extreme thirst
- Pale and cold skin
- Weakness
Severe dengue requires immediate medical attention. Even after recovery, fatigue may persist for weeks.
Diagnosis and Treatment
Since no specific treatment exists for dengue, the main approach is symptom management. Most cases can be treated at home with pain relievers such as acetaminophen (paracetamol). However, non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and aspirin should be avoided as they increase the risk of bleeding.
Severe dengue often requires hospitalization for close monitoring and supportive care.
Global Burden
Dengue cases have surged globally in recent decades. Reports to WHO increased from 505,430 cases in 2000 to 5.2 million in 2019. Many infections are asymptomatic or misdiagnosed, making the actual number significantly higher.
The highest recorded number of cases occurred in 2023, with over 6.5 million reported cases and more than 7,300 deaths. Key factors contributing to the rise in dengue include:
Expansion of mosquito habitats due to climate change
Effects of El Niño, leading to increased temperatures and humidity
Weak healthcare systems, particularly after the COVID-19 pandemic
Political and economic instability, resulting in increased migration
Dengue is endemic in over 100 countries, with the Americas, Southeast Asia, and the Western Pacific being the most affected regions. Asia accounts for approximately 70% of the global dengue burden. The virus is also spreading to new regions, including parts of Europe, the Eastern Mediterranean, and South America.
In 2023, the highest dengue cases were reported in:
- The Americas: 4.5 million cases, 2,300 deaths
- Bangladesh: 321,000 cases
- Malaysia: 111,400 cases
- Thailand: 150,000 cases
- Vietnam: 369,000 cases
Transmission
Mosquito-to-Human Transmission
The dengue virus spreads through bites of infected female mosquitoes, primarily Aedes aegypti. Aedes albopictus can also transmit the virus but plays a secondary role. The transmission cycle begins when a mosquito bites an infected person, allowing the virus to replicate inside the mosquito. After an incubation period of 8–12 days, the mosquito becomes infectious for the rest of its lifespan.
Human-to-Mosquito Transmission
Mosquitoes acquire the virus from infected individuals, even if they are asymptomatic. Infected individuals can transmit the virus to mosquitoes from two days before symptoms appear until two days after fever subsides. Higher viral loads and fever increase the likelihood of mosquito infection.
Maternal Transmission
Though the primary transmission route is via mosquitoes, dengue can be transmitted from a pregnant mother to her baby. The risk of transmission depends on the timing of infection during pregnancy. Maternal dengue infection may lead to complications such as preterm birth, low birth weight, and fetal distress.
Other Transmission Modes
Rare cases of dengue transmission through blood transfusions, organ transplants, and infected needles have been reported. The virus can also be passed from mosquitoes to their offspring via eggs (transovarial transmission).
Risk Factors
Several factors increase the risk of severe dengue and its spread:
Previous Dengue Infection: Those who have had dengue before are at greater risk of severe illness.
Urbanization: Unplanned urban expansion leads to overcrowding, poor waste management, and standing water – all ideal mosquito breeding grounds.
Climate Change: Rising temperatures, increased rainfall, and humidity contribute to mosquito proliferation.
Population Mobility: Increased travel and migration facilitate the spread of dengue to new regions.
Lack of Awareness: Inadequate knowledge about dengue prevention and mosquito control increases community risk.
Prevention and Control
Dengue-spreading mosquitoes are most active during the daytime. Protection measures include:
Wearing clothing that covers most of the body
Using mosquito nets, especially during daytime naps
Installing window screens
Applying mosquito repellents containing DEET, Picaridin, or IR3535
Using mosquito coils and vaporizers
Mosquito breeding can be prevented by:
Eliminating stagnant water from containers
Proper waste disposal to remove mosquito habitats
Cleaning and covering water storage containers weekly
Applying insecticides to outdoor water containers
If infected, follow these guidelines:
Get plenty of rest
Drink fluids to stay hydrated
Use acetaminophen (paracetamol) for fever and pain
Avoid ibuprofen and aspirin
Seek medical attention for severe symptoms
A vaccine called QDenga has been approved in some countries for children aged 6–16 in high-risk areas. Several other vaccines are under development.
WHO Response
The World Health Organization (WHO) supports dengue control through:
Assisting countries in confirming outbreaks via laboratory networks
Providing technical guidance for outbreak management
Enhancing national surveillance and reporting systems
Conducting training on clinical management and vector control
Developing global strategies like the Global Vector Control Response (2017–2030) and the Global Arbovirus Initiative (2022–2025)
Promoting research into new prevention tools and insecticide applications
Collecting and analyzing dengue data from over 100 countries
Publishing guidelines on diagnosis, treatment, and vector management
References
1. Waggoner, J.J., et al. (2016). Viremia and Clinical Presentation in Nicaraguan Patients Infected with Zika Virus, Chikungunya Virus, and Dengue Virus. Clinical Infectious Diseases, 63(12), 1584-1590.
2. Bhatt, S., et al. (2013). The global distribution and burden of dengue. Nature, 496(7446), 504–507.
3. Brady, O.J., et al. (2012). Refining the global spatial limits of dengue virus transmission by evidence-based consensus. PLOS Neglected Tropical Diseases, 6(8), e1760.
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