Dengue Fever
Wikipedia
https://en.wikipedia.org/wiki/Dengue_virus
Dengue fever is a mosquito-borne illness caused by dengue virus, a member of the family Flaviviridae. There are four main types, called serotypes: DENV-1, DENV-2, DENV-3, and DENV-4. Infection generally provides long-lasting immunity to the infecting serotype, but protection against the others is temporary. Consequently, people can develop dengue more than once. A subsequent infection with a different serotype carries an increased risk of severe disease. (CDC, Yellow Book)
Dengue spreads primarily through the bites of infected Aedes aegypti mosquitoes, with Aedes albopictus playing a secondary role. These mosquitoes are active during the day and frequently breed in water-filled containers around homes, including buckets, discarded tires, and water-storage vessels. This close association with people helps dengue spread through urban and suburban communities. (World Health Organization)
Many infections cause no noticeable illness. A 2023 systematic review reported an average asymptomatic proportion of approximately 54%, although estimates varied substantially, and some studies included mild or unrecognized illness within that category. The figure therefore should not be treated as a precise estimate of completely symptom-free infections. (De Santis et al., 2023)
When symptoms occur, they usually begin four to ten days after infection and include high fever, severe headache, pain behind the eyes, muscle and joint pain, nausea, vomiting, and a rash. Symptoms typically last two to seven days, although fatigue may persist after the initial illness has passed. (World Health Organization)
Approximately one in twenty people who become ill with dengue develop severe dengue, a potentially fatal complication. Warning signs include severe abdominal pain, repeated vomiting, bleeding from the nose or gums, blood in vomit or stool, and extreme tiredness or restlessness. These signs often appear as the fever subsides, so a falling temperature does not necessarily mean that the danger has passed. Anyone developing these warning signs needs immediate medical attention. (CDC, symptoms and testing)
Severe dengue can cause blood plasma to leak out of small blood vessels, leading to dangerously low blood pressure, shock, or fluid accumulation that interferes with breathing. Severe bleeding and organ damage can also occur. The broader term “severe dengue” is useful because life-threatening disease does not always involve obvious hemorrhage. Prompt recognition and carefully managed supportive treatment can reduce mortality among patients with severe dengue to below 0.5%. (CDC, clinical features)
In the Amazon, dengue risk is closely connected with human settlements and the conditions that allow its mosquito vectors to thrive. The relationship with deforestation is more complicated than simply assuming that cleared land produces more dengue. A study of Brazil’s Amazonas state found no significant relationship between the amount of deforestation and dengue incidence, illustrating the need to consider settlement patterns, infrastructure, and disease surveillance alongside forest loss. (Kalbus et al., 2021)
Dengue vaccination is available in some countries, but eligibility and protection depend on the vaccine and the population receiving it. Qdenga is one available vaccine; the World Health Organization recommends its use in children aged six to sixteen in settings with high dengue transmission. Its protection varies by serotype and previous infection history, so a single effectiveness percentage does not tell the whole story. (WHO, dengue vaccines) Dengvaxia, an earlier vaccine restricted to people with evidence of previous dengue infection, has been discontinued and is no longer available in the United States. (CDC, dengue vaccines)
Preventing mosquito bites and reducing breeding sites remain essential. Useful measures include insect repellent, window screens, clothing that covers exposed skin, and regularly emptying or covering water-holding containers. There is no specific antiviral treatment for dengue. Treatment focuses on hydration, monitoring, and symptom relief; aspirin and ibuprofen should be avoided because they can increase bleeding risk. (World Health Organization)
References:
Fact sheet for health professionals about Dengue European Centre for Disease Prevent and Control
https://www.ecdc.europa.eu/en/dengue-fever/facts
Dengue Fever Cleveland Clinic
https://my.clevelandclinic.org/health/diseases/17753-dengue-fever
De Santis, Olga. Bouscaren, Nicholas. Flahault, Antoine. (September 16, 2023) Asymptomatic dengue infection rate: A systematic literature review PubMed
https://pmc.ncbi.nlm.nih.gov/articles/PMC10559824/
Dengue World Mosquito Program
Schaefer, Timothy J. Panda, Prasan K. Wolford, Robert W, (March 6, 2024) Dengue fever National Library of Medicine
https://www.ncbi.nlm.nih.gov/books/NBK430732/
Dengue fever Mayo Clinic
https://www.mayoclinic.org/diseases-conditions/dengue-fever/symptoms-causes/syc-20353078
Medagama, Arjuna. Dalugama, Chamara. Meiyalakan, Gukes. Lakmali, Darshani. (April 30, 2020) Risk Factors Associated with Fatal Dengue Hemorrhagic Fever in Adults: A Case Control Study PubMed
https://pmc.ncbi.nlm.nih.gov/articles/PMC7222550/
Dick, Olivia Brathwaite. San Martin, Jose L. Montoya, Romeo H. del Diego. Zambrano, Betzana. Dayan, Gustavo H. (October 3, 2012) The History of Dengue Outbreaks in the Americas PubMed
Lloyd, Christopher. (2009) The Story of the World in 100 Species Bloomsbury
(January 30, 2025) About a Dengue Vaccine Center for Disease Control and Prevention
https://www.cdc.gov/dengue/vaccine/index.html