Short answers, pulled from the story.
Dengue fever is caused by dengue virus, an RNA virus with four serotypes (DENV-1 through DENV-4), belonging to the family Flaviviridae. It is transmitted primarily through the bite of female Aedes aegypti mosquitoes, which prefer to feed at dusk and dawn. A single bite from an infected mosquito is enough to transmit the virus.
A first infection provides lifelong immunity only to that specific serotype, not to the other three. A subsequent infection with a different serotype triggers antibody-dependent enhancement (ADE), where prior antibodies bind the new virus but fail to neutralize it, instead helping it enter immune cells more efficiently. This increases the risk of severe dengue, which can cause plasma leakage, organ failure, and death.
Severe dengue symptoms include severe abdominal pain, persistent vomiting, rapid breathing, bleeding gums or nose, blood in vomit or stool, extreme thirst, pale and cold skin, and feelings of weakness. It can lead to hypovolemic shock, multiple organ failure, and death. Among patients who develop significantly low blood pressure, the fatality rate can reach 26%.
As of March 2024, two vaccines are approved. Dengvaxia (CYD-TDV), available since 2015, is recommended only for individuals who have previously had dengue; Sanofi-Pasteur has stated it will stop manufacturing Dengvaxia during 2026 due to low demand. Qdenga (TAK-003), approved in the European Union in December 2022, can be given to people with no prior infection and is indicated for those four years of age and older.
The World Health Organization estimates that 3.9 billion people are currently at risk of dengue infection. Dengue is endemic in more than 100 countries. During 2023, more than 5 million infections were reported and more than 5,000 dengue-related deaths were recorded, though actual numbers are considered under-reported because most cases are mild or asymptomatic.
The word dengue entered English in the early 19th century from West Indian Spanish, which borrowed it from the Kiswahili term dinga or denga, meaning "cramp-like seizure." The full Kiswahili phrase ki-dinga pepo described it as a seizure caused by an evil spirit. Physician Benjamin Rush called the disease "break-bone fever" in a 1789 report on the 1780 Philadelphia epidemic; the term dengue fever did not come into general use until after 1828.