Mosquito-borne Danger

​Question: What is dengue fever? How does it spread, and how can we best prevent it?

Answer: Dengue fever is a mosquito-borne viral infection that poses a significant global health threat, particularly in tropical and subtropical regions. Transmitted primarily by Aedes aegypti and Aedes albopictus mosquitoes, dengue has seen a dramatic rise in incidence in recent years, exacerbated by factors such as climate change, urbanization, and increased global travel.[1]

As of April 2024 more than 7.6 million dengue cases were reported worldwide, including more than 3,000 deaths. The Americas have been particularly affected, with Brazil alone accounting for more than 6 million suspected cases. Other countries, such as Argentina, Paraguay, and Peru, have also reported significant outbreaks. The World Health Organization (WHO) notes that dengue cases have approximately doubled each year since 2021, with more than 12.3 million cases reported by August 2024. Currently 90 countries have active dengue transmission, and the disease is expanding into new regions, including parts of Europe and the southern United States.[2] ​

Dengue infection can range from mild to severe. Common symptoms include:​

• High fever (up to 104°F or 40°C)

• Severe headaches

• Pain behind the eyes

• Muscle, bone, or joint pain

• Nausea and vomiting

• Swollen glands

• Skin rash​

Severe dengue, also known as dengue hemorrhagic fever, can lead to serious complications, such as bleeding, low platelet count, blood plasma leakage, and organ impairment. Warning signs of severe dengue often appear 24 to 48 hours after the fever subsides and may include severe abdominal pain, persistent vomiting, rapid breathing, bleeding gums, fatigue, and restlessness. ​

Preventing mosquito bites remains the most effective way to avoid dengue infection.

Preventing mosquito bites remains the most effective way to avoid dengue infection.Recommended measures include:​

• Using insect repellents containing DEET, picaridin, or oil of lemon eucalyptus

• Wearing long-sleeved shirts and long pants

• Using mosquito nets and screens on windows and doors

• Eliminating standing water in containers where mosquitoes can breed​

Community-based efforts, such as public education campaigns and mosquito control programs, are crucial in reducing the spread of dengue.​

There are currently two WHO-prequalified dengue vaccines:​[3]

Dengvaxia (CYD-TDV): Approved in 2015, Dengvaxia is recommended for individuals aged 9 to 16 who have had a prior dengue infection and live in endemic areas. It is approved in several countries, including the United States (specifically in such territories as Puerto Rico and the U.S. Virgin Islands), European Union member states, and some Asian and Latin American countries. 

Qdenga (TAK-003): Qdenga received WHO prequalification in May 2024. It is suitable for individuals aged 4 years and older, regardless of prior dengue exposure. Administered in two doses three months apart, Qdenga has been approved in the European Union, Indonesia, Brazil, and other countries with high dengue burdens. ​

The prequalification of Qdenga by WHO facilitates broader access in endemic regions. Availability, however, may still be limited in some areas because of logistical and regulatory challenges.​

Dengue fever continues to be a pressing global health issue, with increasing incidence and expanding geographic reach. While preventive measures remain the frontline defense against infection, the development and distribution of effective vaccines such as Dengvaxia and Qdenga offer promising tools in the fight against dengue. Be sure to consult with your physician as to the advisability and suitability of vaccination for your circumstances.

[1] Retrieved from https://www.mayoclinic.org/diseases-conditions/dengue-fever/symptoms-causes/syc-20353078? 

[2] https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON518? 

[3] https://www.who.int/americansamoa/news/detail-global/15-05-2024-who-prequalifies-new-dengue-vaccine?