Last month, the Dengue Vaccine Initiative began posting daily questions and answers on its Twitter page as part of a new series called Dengue Basics. The questions and answers relayed were simple, yet informative facts about dengue, the development of a dengue vaccine and the efforts of the Dengue Vaccine Initiative. The series ended last Friday, March 23, and we wanted to provide a one-stop source for all the Q&A’s shared via Twitter.

Here is Dengue Basics in its entirety. Additional information about any of the topics below can be found at the following websites:,, and Also, please feel free to tweet your dengue-related questions to @preventdengue!
Q. How is dengue transmitted?
A. Dengue is primarily transmitted to humans by the Aedes aegypti mosquito.
Q. What are some ideal breeding locations for mosquitoes that transmit dengue?
A. Water containers, flower pots, old tires and other items that collect rainwater are ideal mosquito breeding locations.
Q. Where does dengue occur?
A. Dengue occurs in tropical and sub-tropical areas of the world.
Q. Where is dengue found?
A. Dengue is now endemic in more than 100 countries in the Americas, the Eastern Mediterranean, South-East Asia, the Western Pacific and Africa.
Q. What are the symptoms of dengue?
A. Dengue symptoms range from a mild fever, to incapacitating high fever, with severe headache, muscle and joint pain, and rash.
Q. How long does it take for dengue symptoms to appear?
A. Dengue symptoms appear in 3-14 days (average 4-7 days) after the infective bite.
Q. Why is dengue worse the second time you get it?
A. People who have had dengue once are more likely to contract severe dengue, which can lead to hemorrhage, shock, coma and death.
Q. How many people are at risk of dengue infection?
A. It’s estimated that as many as 3 billion people – 2/5s of the world’s population – are at risk of dengue infection.
Q. What are the main causes of the rapid rise in dengue cases?
A. Rapid urbanization, poor water and waste management systems, international travel, & climate change attributed to rise of dengue.
Q. How many people with dengue require hospitalization?
A. Experts estimate that in any given year there are up to 500,000 cases of severe dengue requiring hospitalization.
Q. How often do dengue outbreaks occur?
A. In countries where dengue is endemic, outbreaks occur annually, usually during the rainy season when mosquito populations are high.
Q. Are travelers at risk of contracting dengue?
A. Yes. More than 125 million tourists visit dengue endemic countries annually and are therefore at risk of infection.
Q. Have there been dengue cases in the U.S.?
A. Yes. As recently as 2011, non-travel related outbreaks of dengue have reported in Florida, Hawaii and Texas.
Q. Are there any drugs available to treat dengue?
A. No. There are no drugs available to prevent or treat dengue infection.
Q. When is a dengue vaccine expected?
A. There are multiple vaccine candidates undergoing clinical trials, the most advanced of which could be licensed by 2015.
Q. Is it challenging to develop a dengue vaccine?
A. Yes. The vaccine must immunize against all 4 related viruses that can cause dengue to be effective. (More information here:
Q. How effective is vector control?
A. Vector control is an integral part of any dengue control strategy, but it’s not enough on its own.
Q. What is the economic impact of dengue?
A. The substantial economic impact of dengue includes lost wages, decreased productivity and the costs of obtaining care.
Q. What is the mission of the Dengue Vaccine Initiative?
A. DVI’s mission is to encourage the development and use of vaccines to prevent the millions of annual dengue cases.
Q. What are the 4 organizations that make up DVI?
A. DVI is the International Vaccine Institute, the WHO, the International Vaccine Access Center and the Sabin Vaccine Institute. More information about DVI’s members here:
Q. What is DVI doing to achieve its goal of a world free of dengue?
A. DVI is conducting evidence-based research, working with countries & partnering with governments. More information here: