According to the World Health Organization, up to 2.5 billion people across the world are at risk for dengue infections.  Dengue virus infects up to 100 million and results in over 500,000 hospitalizations and 12,500 deaths each year. Its impact is magnified by the lack of effective antiviral drugs and vaccines.

Dengue fever can be caused by any one of four serotypes of dengue virus:  DEN-1, DEN-2, DEN-3 and DEN-4. These viruses are part of the Flavivirus family, which includes West Nile virus and yellow fever virus. Dengue virus is spread by mosquitoes, and is most common during the rainy seasons throughout the world’s tropical and subtropical regions. Dengue does not spread directly from person to person. An individual infected by one serotype of dengue virus develops lifelong immunity against that serotype, but not against other serotypes.

Symptoms of classic dengue fever include high fever, severe headache and/or pain behind the eyes, severe joint and muscle pain, nausea and vomiting. A few days after fever onset, a rash often develops over most of the body and lasts for one to two days. The rash can reappear several days later. These symptoms typically begin within a week after infection, and usually resolve without treatment.

Dengue hemorrhagic fever is a more serious form of disease which can include all of the symptoms of classic dengue fever plus leakage of blood plasma into tissues caused by noticeable damage to blood vessels and lymph vessels, bleeding from the nose and gums, and conspicuous bruising under the skin. Dengue hemorrhagic fever can lead to death. The most severe form of dengue disease is dengue shock syndrome, which includes all of the symptoms of classic dengue and dengue hemorrhagic fever, plus massive leaking of blood plasma outside of blood vessels, extensive bleeding, and shock caused by extremely low blood pressure. Dengue shock syndrome most often occurs in children infected for a second time (with a different serotype of dengue), and can be fatal.