The World Health Organization (WHO) has updated its fact sheet on Dengue and severe dengue.
Key Messages:
Introduction:
Dengue is a mosquito-borne viral disease that 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.
Severe dengue (also known as Dengue Haemorrhagic Fever) affects most Asian and Latin American countries and has become a leading cause of hospitalization and death among children in these regions.
Vector habits:
The Aedes aegypti mosquito lives in urban habitats and breeds mostly in man-made containers. Unlike other mosquitoes Ae. aegypti is a day-time feeder; its peak biting periods are early in the morning and in the evening before dusk. Female Ae. aegyptibites multiple people during each feeding period.
Immune response:
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 serotype 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.
Global Disease Burden:
The full global burden of the disease is uncertain- one estimate indicates 390 million dengue infections per year, of which 96 million manifest clinically (with any severity of disease); Another study estimates that 3.9 billion people, in 128 countries, are at risk of infection with dengue viruses.
An estimated 500 000 people with severe dengue require hospitalization each year, a large proportion of whom are children. About 2.5% of those affected die.
Clinical features:
Dengue should be suspected when a high fever (40°C/104°F) is accompanied by 2 of the following symptoms:
- severe headache
- pain behind the eyes
- muscle and joint pains
- nausea
- vomiting
- swollen glands or
- rash.
Symptoms usually last for 2–7 days, after an incubation period of 4–10 days after the bite from an infected mosquito.
Severe dengue is a potentially deadly complication due to plasma leaking, fluid accumulation, respiratory distress, severe bleeding, or organ impairment.
Warning signs of severe dengue occur 3–7 days after the first symptoms in conjunction with a decrease in temperature (below 38°C/100°F) and include:
- severe abdominal pain
- persistent vomiting
- rapid breathing
- bleeding gums
- fatigue
- restlessness and
- blood in vomit.
The next 24–48 hours of the critical stage can be lethal; proper medical care is needed to avoid complications and risk of death.
Treatment:
There is no specific treatment for dengue fever.
Vaccination:
In late (December) 2015 and early 2016, the first dengue vaccine, Dengvaxia (CYD-TDV) by Sanofi Pasteur, was registered in several countries for use in individuals 9-45 years of age living in endemic areas.
The Strategic Advisory Group of Experts (SAGE) on immunization will review the dengue vaccine and recommendations are expected in April 2016.
Prevention and Control:
At present, the only method to control or prevent the transmission of dengue virus is to combat vector mosquitoes through:
- preventing mosquitoes from accessing egg-laying habitats by environmental management and modification;
- disposing of solid waste properly and removing artificial man-made habitats;
- covering, emptying and cleaning of domestic water storage containers on a weekly basis;
- applying appropriate insecticides to water storage outdoor containers;
- using of personal household protection such as window screens, long-sleeved clothes, insecticide treated materials, coils and vaporizers;
- improving community participation and mobilization for sustained vector control;
- applying insecticides as space spraying during outbreaks as one of the emergency vector-control measures
Useful Links:
Link to the updated fact sheet:
Link to WHO’s ‘Dengue: guidelines for diagnosis, treatment, prevention and control — New edition’ (published in 2009):
Link to WHO’s Global Strategy for Dengue Prevention and Control 2012-2020 (published in 2012):
Link to WHO’s page on Dengue Vaccine Research:
http://who.int/immunization/research/development/dengue_vaccines/en/
Author:
Dr. Liaquat Roopesh MBBS, MD (Community Medicine)
Author:
Dr. Liaquat Roopesh MBBS, MD (Community Medicine)
Alumnus of Christian Medical College, Vellore.
Interests: teaching and medical education
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