Dengue viruses are spread to people through the bite of an infected mosquito from the Aedes species. While most dengue cases are asymptomatic, when symptomatic they can cause dengue fever and more severe problems like hemorrhagic fever – a type of fever that can cause serious bleeding, a sudden drop in blood pressure (shock) and death – or dengue shock syndrome – essentially a sudden decrease in the flow of blood.

Dengue infections are caused by four very similar viruses, called serotypes, named DEN-1, DEN-2, DEN-3, and DEN-4. These viruses are called serotypes because each one interacts a bit differently with antibodies in human blood. These dengue serotypes are very similar, sharing approximately 65% of their genomes. Each serotype also causes the same disease and typically results in similar symptoms in a person who is infected. 

However, four serotypes of dengue makes immunity tricky. If a person is infected with one of the serotypes, data shows that they are likely to be protected for life against that one serotype; but protection against the other three serotypes is only partial and temporary. This makes dengue a hard virus to control and protect against. 

In addition, research shows that most likely, the four serotypes are not equally severe. While all serotypes can cause severe disease and even death, reports, for instance, suggest that DEN-2 and DEN-3 are more likely to cause severe infection than the other serotypes. 

The dengue virus was isolated for the first time in 1943 by scientists Ren Kimura and Susumu Hotta in Japan. We now know that the serotype they isolated was DEN-1. 

The time and location of the first dengue fever outbreak is less clear. The first confirmed documented outbreak of dengue was in 1779 across Asia, North America, and Africa simultaneously. However, there have been documented outbreaks of illnesses causing fever with similar symptoms to dengue for many centuries. The first documented epidemic of this kind was recorded in 1635 in Martinique and Guadeloupe in the West Indies. 

It’s also difficult to know exactly why or how dengue evolved, but scientists hypothesize that the dengue viruses evolved in nonhuman primates and then jumped to humans in Africa or Southeast Asia between 500 and 1,000 years ago. 

Dengue continues to be a leading cause of illness in areas that are at high risk for dengue. Outbreaks continue to impact many countries globally, especially ones with warmer climates.

Dengue is a major contributor to the global burden of disease globally, especially in warmer climates. Given that a dengue vaccine became commercially available in 2021, and because dengue is beginning to spread to places it has not been seen in a long time (eg. Florida, USA), there has been greater attention on dengue, including its origins, its symptoms, and its prevention.