Dengue is transmitted by the bite of an infected mosquito. It is an illness that affects infants, young children, and adults, with symptoms ranging from mild fever to incapacitating high fever, with severe headache, pain behind the eyes, muscle and joint pain, and rash. The illness can evolve to severe dengue, characterized by shock, respiratory distress, severe bleeding, and/or serious organ impairment. The disease has a seasonal pattern: most cases in the southern hemisphere occur in the first half of the year, and most cases in the northern hemisphere in the second half. This pattern corresponds to the warmer, rainy months.
In the Americas, Aedes aegypti is the mosquito vector that is the main source of dengue transmission.
- Approximately 500 million people in the Americas are today at risk of dengue.
- Dengue incidence has increased in the Americas over the past four decades, from 1.5 million cumulative cases in the 1980s to 16,2 million in the decade 2010-2019.
- 2013 was an epidemic year in the Americas, with 2 million cases and an incidence of 430,8 per 100,000 inhabitants. There were 37,692 severe cases and 1,280 deaths in the hemisphere. In 2019, more than 3,1 million cases were registered, 28,000 severe and, 1,534 deaths
- The four dengue serotypes (DENV-1, DENV-2, DENV-3 and DENV-4) circulate throughout the Americas, and in some countries simultaneously.
- Following infection with one serotype, subsequent infection with a different serotype increases a person's risk of severe dengue and death.
- Ae. aegypti is the vector mosquito for dengue and is widely distributed in the Americas. Only Canada and continental Chile are free from dengue and its vector. Uruguay has no dengue cases, but it does have Ae. aegypti.
- It is transmitted by the bite of a mosquito infected with one of the four serotypes of dengue virus.
- It is a febrile illness that affects infants, children and adults. The infection may be asymptomatic, or it may present with symptoms ranging from a moderate fever to a disabling high fever, with severe headache, pain behind the eyes, muscle and joint pain, and rashes. The disease can evolve into severe dengue, characterized by shock, shortness of breath, severe bleeding and / or complications in the organs.
- There is no a specific medicine to treat dengue.
- The disease has a pattern according to the seasons: the majority of cases in the southern hemisphere occur in the first part of the year, and the majority of cases in the northern hemisphere occur in the second half.
- Dengue prevention and control must be intersectoral and involve the family and the community.
About Aedes aegypti
Aedes aegypti is the vector that presents the greatest risk of arbovirus transmission in the Americas and is present in almost all countries of the hemisphere (except Canada and continental Chile). It is a domestic mosquito (that lives in and near houses) that reproduces in any artificial or natural container that contains water.
The mosquito can complete its life cycle, from the egg to the adult, in 7-10 days; adult mosquitoes usually live 4 to 6 weeks. The female Aedes aegypti is responsible for the transmission of diseases because she needs human blood for the development of her eggs and for her metabolism. The male does not feed on blood.
The mosquito is most active early in the morning and at dusk, so these are the periods of greatest risk of bites. However, females, who need to continue feeding, will seek a source of blood at other times. The female Aedes aegypti feeds every 3-4 days; however, if they cannot draw enough blood, they continue feeding each moment they can.
Aedes aegypti prefers to lay its eggs in artificial containers that contain water (drums, barrels and tires, mainly) in and around homes, schools and workplaces. Aedes aegypti eggs can withstand dry environmental conditions for more than a year: in fact, this is one of the most important strategies that the species uses to survive and spread.
To eliminate mosquitoes, the following actions are recommended: avoid collecting water in open-air containers (pots, bottles or other containers that can collect water) so that they do not become breeding sites for mosquitoes; adequately cover water tanks and reservoirs to keep mosquitoes away; avoid accumulating garbage, throwing garbage in closed plastic bags.
- PAHO/WHO provides advice and technical support for dengue prevention and control based on a regional strategy adopted by PAHO / WHO member States in 2016, called the "Strategy for arboviral disease prevention and control" (CD55.R6).
- In 2008, PAHO / WHO Member States established a Network of Dengue Laboratories of the Americas (RELDA), to strengthen technical capacities for diagnosing dengue. RELDA has now been expanded to include chikungunya and Zika fever and now comprises 32 laboratories in 26 countries of the Region.
- PAHO/WHO is supporting the development of an integrated dengue surveillance system model in the context of the circulation of other arboviruses to generate standardized information for all the Americas.
- In 2010, PAHO / WHO adapted the 2009 WHO clinical guidelines on the management of dengue patients for use in the Americas. After its implementation, the lethality rate in dengue cases decreased in 2019 from 0,07% to 0,05%, which means a 30% reduction. A second edition of the PAHO / WHO clinical guidelines was published in 2015, incorporating new elements, including dengue during pregnancy, dengue in newborns, dengue in the elderly and preparation and response to dengue outbreaks.
- A tool for the diagnosis and care of patients with suspected arbovirosis (dengue, chikungunya and Zika) was published in 2016. Currently, the first clinical guide for arbovirosis is being developed following the GRADE methodology. This guide will be published in 2020.