Dengue virus is the causative agent of dengue fever (DF), dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS). The virus is found in tropical and sub-tropical regions around the world, where is it is typically transmitted by the Aedes aegypti mosquito which is highly adapted to living with people.

Dengue has reemerged as a major global public health concern. Dengue virus is endemic in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, South-east Asia and the Western Pacific. Approximately 40% of the world’s population (~2.5 billion people) is at risk for infection either because they live in endemic areas or in regions where the primary mosquito vector is present.  Estimates of the number of people infected each year range from 50 million (World Health Organization estimate) to 100 million (NIH estimate).  Each year, over one million clinical cases of DF and 500,000 cases of DHF require hospitalization. DHF has a mortality rate of ~5%.

Dengue fever (DF) is a severe flu-like illness that presents as non-specific febrile illness, rash, very high fever (104-105 degrees Fahrenheit), severe headache, extreme muscle and joint pain, nausea, vomiting, and enlarged lymph nodes. Dengue hemorrhagic fever (DHF) is a life-threatening disease with early symptoms that are very similar to those of DF including very high fever, headache, muscle and joint aches, malaise, decreased appetite and vomiting.  After several days, the patient may undergo symptoms of irritability, restlessness, and excess perspiration.

Hemorrhagic phenomena, such as petechiae and ecchymoses (spots or patches of blood on or under the skin) and increased bleeding from injury are observed.  Further complications include liver enlargement and circulatory failure.  Dengue shock syndrome (DSS) usually occurs after days 2-6.  Patients usually exhibit the symptoms of DF and DHF and may suffer sudden collapse, “clammy” extremities, decrease in pulse, and circumoral cyanosis (blueness around mouth).  Hemorrhagic phenomenon is notable as patients exhibit spitting up of blood, nosebleeds, bleeding gums, and blood in the stool.  This is most often observed in children under 10 years of age, and once patients reach this stage, the mortality rate can reach as high as 30%.

 There are four serotypes of dengue virus.  Infection by one serotype does protect from future infections by the same serotype, but does not offer cross protection for infection from one of the other serotypes.  In fact, there is some evidence that a second infection by a different serotype can cause a phenomenon known as “immune enhancement” which may lead to a more severe form of the disease from the second infection.  This is one of the challenges faced by those trying to develop dengue vaccines. 

The Aedes aegypti mosquito is the most common dengue vector.

World Distribution of

dengue fever and

 dengue fever with dengue hemorrhagic fever

Links for more information:

World Health Organization

Centers for Disease Control (CDC)

U.S. National Institutes of Health

Virginia Bioinformatics Institute