Key information
- Dengue is a viral an infection transmitted to people by the chew of contaminated mosquitoes.
- About half of the world’s inhabitants is now prone to dengue with an estimated 100–400 million infections occurring annually.
- Dengue is present in tropical and sub-tropical climates worldwide, principally in city and semi-urban areas.
- Whereas many dengue infections are asymptomatic or produce solely delicate sickness, the virus can sometimes trigger extra extreme instances, and even demise.
- Prevention and management of dengue depend upon vector management. There isn’t a particular remedy for dengue/extreme dengue, and early detection and entry to correct medical care significantly decrease fatality charges of extreme dengue.
Overview
Dengue (break-bone fever) is a viral an infection that spreads from mosquitoes to individuals. It’s extra frequent in tropical and subtropical climates.
Most individuals who get dengue is not going to have signs. However for many who do, the most typical signs are excessive fever, headache, physique aches, nausea, and rash. Most will get higher in 1–2 weeks. Some individuals develop extreme dengue and wish care in a hospital.
In extreme instances, dengue will be deadly.
You’ll be able to decrease your threat of dengue by avoiding mosquito bites particularly through the day.
Dengue is handled with ache medication as there isn’t a particular remedy presently.
Signs
Most individuals with dengue have delicate or no signs and can get higher in 1–2 weeks. Hardly ever, dengue will be extreme and result in demise.
If signs happen, they often start 4–10 days after an infection and final for two–7 days. Signs might embrace:
- excessive fever (40°C/104°F)
- extreme headache
- ache behind the eyes
- muscle and joint pains
- nausea
- vomiting
- swollen glands
- rash.
People who’re contaminated for the second time are at better threat of extreme dengue.
Extreme dengue signs usually come after the fever has gone away:
- extreme stomach ache
- persistent vomiting
- speedy respiration
- bleeding gums or nostril
- fatigue
- restlessness
- blood in vomit or stool
- being very thirsty
- pale and chilly pores and skin
- feeling weak.
Individuals with these extreme signs ought to get care immediately.
After restoration, individuals who have had dengue might really feel drained for a number of weeks.
Diagnostics and remedy
There isn’t a particular remedy for dengue. The main target is on treating ache signs. Most instances of dengue fever will be handled at dwelling with ache medication.
Acetaminophen (paracetamol) is commonly used to regulate ache. Non-steroidal anti-inflammatory medicine like ibuprofen and aspirin are averted as they will improve the danger of bleeding.
For individuals with extreme dengue, hospitalization is commonly wanted.
World burden
The incidence of dengue has grown dramatically world wide in current a long time, with instances reported to WHO rising from 505 430 instances in 2000 to five.2 million in 2019. A overwhelming majority of instances are asymptomatic or delicate and self-managed, and therefore the precise numbers of dengue instances are under-reported. Many instances are additionally misdiagnosed as different febrile sicknesses (1).
The best variety of dengue instances was recorded in 2023, affecting over 80 nations in all areas of WHO. Because the starting of 2023 ongoing transmission, mixed with an surprising spike in dengue instances, resulted in a historic excessive of over 6.5 million instances and greater than 7300 dengue-related deaths reported.
A number of components are related to the rising threat of unfold of the dengue epidemic: the altering distribution of the vectors (mainly Aedes aegypti and Aedes albopictus mosquitoes), particularly in beforehand dengue naïve nations; the results of El Niño phenomena in 2023 and local weather change resulting in rising temperatures and excessive rainfall and humidity; fragile well being techniques within the midst of the COVID-19 pandemic; and political and monetary instabilities in nations going through advanced humanitarian crises and excessive inhabitants actions.
One modelling estimate signifies 390 million dengue virus infections per yr of which 96 million manifest clinically (2). One other research on the prevalence of dengue estimates that 3.9 billion individuals are prone to an infection with dengue viruses (3).
The illness is now endemic in additional than 100 nations within the WHO Areas of Africa, the Americas, the Japanese Mediterranean, South-East Asia and the Western Pacific. The Americas, South-East Asia and Western Pacific areas are essentially the most critically affected, with Asia representing round 70% of the worldwide illness burden.
Dengue is spreading to new areas in Europe, the Japanese Mediterranean and South America.
The most important variety of dengue instances reported was in 2023. The WHO Area of the Americas reported 4.5 million instances, with 2300 deaths. A excessive variety of instances have been reported in Asia: Bangladesh (321 000), Malaysia (111 400), Thailand (150 000), and Viet Nam (369 000).
Transmission
Transmission by the mosquito chew
The dengue virus is transmitted to people by the bites of contaminated feminine mosquitoes, primarily the Aedes aegypti mosquito. Different species throughout the Aedes genus may also act as vectors, however their contribution is generally secondary to Aedes aegypti. Nevertheless, in 2023, a surge in native transmission of dengue by Aedes albopictus (tiger mosquito) has been seen in Europe.
After feeding on a contaminated individual, the virus replicates within the mosquito midgut earlier than disseminating to secondary tissues, together with the salivary glands. The time it takes from ingesting the virus to precise transmission to a brand new host is termed the extrinsic incubation interval (EIP). The EIP takes about 8–12 days when the ambient temperature is between 25–28°C. Variations within the extrinsic incubation interval usually are not solely influenced by ambient temperature; a number of components such because the magnitude of day by day temperature fluctuations, virus genotype, and preliminary viral focus may also alter the time it takes for a mosquito to transmit the virus. As soon as infectious, the mosquito can transmit the virus for the rest of its life.
Human-to-mosquito transmission
Mosquitoes can turn out to be contaminated by people who find themselves viremic with the dengue virus. This may be somebody who has a symptomatic dengue an infection, somebody who’s but to have a symptomatic an infection (they’re pre-symptomatic), and in addition somebody who reveals no indicators of sickness (they’re asymptomatic).
Human-to-mosquito transmission can happen as much as 2 days earlier than somebody reveals signs of the sickness, and as much as 2 days after the fever has resolved.
The chance of mosquito an infection is positively related to excessive viremia and excessive fever within the affected person; conversely, excessive ranges of DENV-specific antibodies are related to a decreased threat of mosquito an infection. Most individuals are viremic for about 4–5 days, however viremia can final so long as 12 days.
Maternal transmission
The first mode of transmission of the dengue virus between people entails mosquito vectors. There may be proof nevertheless, of the potential for maternal transmission (from a pregnant mom to her child). On the similar time, vertical transmission charges seem low, with the danger of vertical transmission seemingly linked to the timing of the dengue an infection through the being pregnant. When a mom does have a dengue an infection when she is pregnant, infants might endure from pre-term delivery, low birthweight, and fetal misery.
Different transmission modes
Uncommon instances of transmission by way of blood merchandise, organ donation and transfusions have been recorded. Equally, transovarial transmission of the virus inside mosquitoes have additionally been recorded.
Danger components
Earlier an infection with DENV will increase the danger of the person creating extreme dengue.
Urbanization (particularly unplanned), is related to dengue transmission by a number of social and environmental components: inhabitants density, human mobility, entry to dependable water supply, water storage follow and many others.
Neighborhood dangers to dengue additionally depend upon a inhabitants’s data, perspective and follow in the direction of dengue, because the publicity is intently associated to behaviours corresponding to water storage, plant conserving, and self-protection in opposition to mosquito bites. Routine vector surveillance and management actions participating neighborhood significantly enhances a neighborhood’s resilience.
Vectors would possibly adapt to new environments and local weather. The interplay between dengue virus, the host and the setting is dynamic. Consequently, illness dangers might change and shift with local weather change in tropical and subtropical areas, together with elevated urbanization and motion of populations.
Prevention and management
The mosquitoes that unfold dengue are lively through the day.
Decrease the danger of getting dengue by defending your self from mosquito bites through the use of:
- garments that cowl as a lot of your physique as attainable;
- mosquito nets if sleeping through the day, ideally nets sprayed with insect repellent;
- window screens;
- mosquito repellents (containing DEET, Picaridin or IR3535); and
- coils and vaporizers.
Mosquito breeding will be prevented by:
- stopping mosquitoes from accessing egg-laying habitats by environmental administration and modification;
- disposing of stable waste correctly and eradicating synthetic man-made habitats that may maintain water;
- overlaying, emptying and cleansing home water storage containers on a weekly foundation;
- making use of applicable pesticides to outside water storage containers.
In the event you get dengue, it’s vital to:
- relaxation;
- drink loads of liquids;
- use acetaminophen (paracetamol) for ache;
- keep away from non-steroidal anti-inflammatory medicine, like ibuprofen and aspirin; and
- look ahead to extreme signs and get in touch with your physician as quickly as attainable in the event you discover any.
Up to now one vaccine (QDenga) has been accepted and licensed in some nations. Nevertheless, it’s endorsed just for the age group of 6 to 16 years in excessive transmission settings. A number of extra vaccines are underneath analysis.
WHO response
WHO responds to dengue within the following methods:
- helps nations within the affirmation of outbreaks by its collaborating community of laboratories;
- gives technical help and steerage to nations for the efficient administration of dengue outbreaks;
- helps nations in bettering their reporting techniques and seize the true burden of the illness;
- gives coaching on scientific administration, prognosis and vector management on the nation and regional stage with a few of its collaborating centres;
- formulates evidence-based methods and insurance policies;
- help nations within the growth of dengue prevention and management methods and adopting the World Vector Management Response (2017–2030) and the World Arbovirus Initiative (2022–2025).
- evaluations and recommends the event of latest instruments, together with insecticide merchandise and utility applied sciences;
- gathers official information of dengue and extreme dengue from over 100 Member States; and
- publishes pointers and handbooks for surveillance, case administration, prognosis, dengue prevention and management for Member States.
References
- Waggoner, J.J., et al., Viremia and Scientific Presentation in Nicaraguan Sufferers Contaminated Wi1. Waggoner, J.J., et al., Viremia and Scientific Presentation in Nicaraguan Sufferers Contaminated With Zika Virus, Chikungunya Virus, and Dengue Virus. Scientific Infectious Ailments, 2016. 63(12): p. 1584-1590.
- Bhatt, S., et al., The worldwide distribution and burden of dengue. Nature, 2013. 496(7446): p. 504–507.
- Brady, O.J., et al., Refining the worldwide spatial limits of dengue virus transmission by evidence-based consensus. PLOS Uncared for Tropical Ailments, 2012. 6(8): p. e1760.