Dengue

Additional Information

Dengue and severe dengue

Dengue vaccine: WHO position paper – July 2016 pdf 437kb Global strategy for dengue prevention and control 2012-2020 pdf 686kB

Factsheet

Key Facts

• Dengue is a mosquito-borne viral infection.
• The infection causes flu-like illness, and occasionally develops into a potentially lethal complication called severe dengue.
• The global incidence of dengue has grown dramatically in recent decades. About half of the world's population is now at risk.
• Dengue is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas.
• Severe dengue is a leading cause of serious illness and death among children in some Asian and Latin American countries.
• There is no specific treatment for dengue/ severe dengue, but early detection and access to proper medical care lowers fatality rates below 1%.
• Dengue prevention and control depends on effective vector control measures.
• A dengue vaccine has been licensed by several National Regulatory Authorities for use in people 9-45 years of age living in endemic settings.

Dengue is a mosquito-borne viral disease that has rapidly spread in all regions of WHO in recent years. Dengue virus is transmitted by female mosquitoes mainly of the species Aedes aegypti and, to a lesser extent, Ae. albopictus. This mosquito also transmits chikungunya, yellow fever and Zika infection. Dengue is widespread throughout the tropics, with local variations in risk influenced by rainfall, temperature and unplanned rapid urbanization.

Severe dengue (also known as Dengue Haemorrhagic Fever) was first recognized in the 1950s during dengue epidemics in the Philippines and Thailand. Today, severe dengue affects most Asian and Latin American countries and has become a leading cause of hospitalization and death among children and adults in these regions.

There are 4 distinct, but closely related, serotypes of the virus that cause dengue (DEN-1, DEN-2, DEN-3 and DEN-4). Recovery from infection by one provides lifelong immunity against that particular serotype. However, cross-immunity to the other serotypes after recovery is only partial and temporary. Subsequent infections by other serotypes increase the risk of developing severe dengue.

Dengue fever is an arbovirus transmitted by Aedes mosquitoes (both Ae. aegypti and Ae. albopiticus). It is a severe, flu-like illness that affects infants, young children and adults, but seldom causes death.

Dengue haemorrhagic fever (DHF) is a potentially deadly complication that has become a leading cause of hospitalization and death among children in Asia. There is good evidence that sequential infection with the different serotypes of dengue virus increases the risk of more severe disease that can result in shock syndrome and death. 

There is no specific treatment for dengue, but appropriate medical care frequently saves the lives of patients with dengue haemorrhagic fever.  

Infected humans are the main carriers and multipliers of the virus, serving a source of the virus for uninfected Aedes aegypti mosquitoes which maintain the urban dengue transmission cycle. The virus circulates in the blood of infected human for 2 to 7 days, at approximately the same time that they have a fever. 

At present, the only method of controlling or preventing dengue virus transmission is to combat the vector mosquitoes using environmental management and chemical methods.