Key Points
- Dengue is a viral infection caused by the dengue virus (DENV), transmitted to humans through the bite of infected mosquitoes.
- About half of the world’s population is now at risk of dengue, with an estimated 100–400 million infections occurring each year.
- Dengue is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas.
- While many DENV infections are asymptomatic or produce only mild illness, DENV can occasionally cause more severe cases and even death.
- Prevention and control of dengue depend on vector control. There is no specific treatment for dengue/severe dengue, and early detection and access to proper medical care greatly lower fatality rates of severe dengue.
Overview
Dengue fever, often referred to as “break-bone fever,” is a viral infection transmitted to humans through the bites of infected mosquitoes, primarily the Aedes aegypti mosquito. It is most prevalent in tropical and subtropical regions.
While many individuals infected with dengue may remain asymptomatic, those who do develop symptoms typically experience a high fever, severe headaches, muscle and joint pain, nausea, and a rash. In most cases, these symptoms resolve within 1 to 2 weeks. However, in severe cases, dengue can be life-threatening.
Symptoms
The onset of dengue symptoms usually occurs 4 to 10 days after infection and may persist for 2 to 7 days. Common symptoms include:
- High fever (reaching up to 40°C or 104°F)
- Severe headaches
- Pain behind the eyes
- Muscle and joint pains
- Nausea
- Vomiting
- Swollen glands
- Rash
It’s important to note that individuals who have had a previous dengue infection are at a higher risk of developing severe dengue. Severe dengue symptoms often manifest after the fever has subsided and may include:
- Severe abdominal pain
- Persistent vomiting
- Rapid breathing
- Bleeding gums or nosebleeds
- Fatigue
- Restlessness
- Presence of blood in vomit or stool
- Excessive thirst
- Pale and cold skin
- Weakness
Anyone experiencing these severe symptoms should seek immediate medical attention. After recovery from dengue, individuals may experience fatigue for several weeks.
Diagnosis and Treatment
Most cases of dengue fever can be managed at home with pain-relief medication. The primary focus of treatment is on alleviating symptoms. Acetaminophen (paracetamol) is commonly used to control pain, while non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and aspirin are avoided due to their potential to increase the risk of bleeding.
A vaccine called Dengvaxia is available for individuals who have previously had dengue and reside in areas where the disease is prevalent. However, this vaccine is not suitable for those who have not had a previous dengue infection.
In severe cases of dengue, hospitalization is often necessary.
Global Burden
Dengue incidence has surged worldwide in recent decades, with reported cases to the World Health Organization (WHO) escalating from 505,430 in 2000 to 5.2 million in 2019. It’s important to note that the actual number of dengue cases is likely higher than reported figures, as many cases go undetected or are misdiagnosed as other febrile illnesses.
The disease is now endemic in over 100 countries, with regions such as the Americas, South-East Asia, and the Western Pacific being the most severely affected. Dengue has also spread to new areas, including Europe, with several countries reporting local transmission.
Transmission
Dengue is primarily transmitted through the bites of infected female mosquitoes, particularly Aedes aegypti. Additionally, human-to-mosquito transmission can occur up to 2 days before and after the onset of symptoms. There is also evidence of maternal transmission from pregnant mothers to their babies, although this is relatively rare. Other transmission modes, such as through blood products, organ donation, transfusions, and transovarial transmission within mosquitoes, have been recorded.
Risk Factors
Previous dengue infections increase the risk of developing severe dengue. Urbanization, particularly unplanned urbanization, is associated with increased dengue transmission due to factors like population density, human mobility, and access to water sources. The community’s vulnerability to dengue depends on their knowledge, attitudes, and practices regarding the disease, as well as the implementation of sustainable vector control measures.
Prevention and Control
Preventing mosquito bites is the most effective way to reduce the risk of dengue. This can be achieved by:
- Wearing clothing that covers the body
- Using mosquito nets, ideally treated with insect repellent, when sleeping during the day
- Installing window screens
- Applying mosquito repellents containing DEET, Picaridin, or IR3535
- Using mosquito coils and vaporizers
If you contract dengue, it’s essential to:
- Get plenty of rest
- Stay well-hydrated
- Use acetaminophen (paracetamol) for pain relief
- Avoid NSAIDs like ibuprofen and aspirin
- Monitor for severe symptoms and seek medical attention promptly if they arise
While Dengvaxia is available for certain populations, no specific antiviral treatment for dengue exists.
WHO Response
The World Health Organization (WHO) responds to dengue by:
- Assisting countries in confirming outbreaks through its network of laboratories
- Providing technical support and guidance for outbreak management
- Supporting countries in improving reporting systems
- Offering training on clinical management, diagnosis, and vector control
- Formulating evidence-based strategies and policies
- Assisting countries in developing dengue prevention and control strategies
- Reviewing and recommending the development of new tools for vector control
- Collecting official dengue records from over 100 Member States
- Publishing guidelines and handbooks for surveillance, case management, diagnosis, prevention, and control of dengue for Member States.
References:
1. Bhatt, S., et al., The global distribution and burden of dengue. Nature, 2013. 496(7446): p. 504–507.
2. Brady, O.J., et al., Refining the global spatial limits of dengue virus transmission by evidence-based consensus. PLOS Neglected Tropical Diseases, 2012. 6(8): p. e1760.