<s>[INST] What is dengue fever and severe dengue? [/INST] Dengue is a vector-borne disease transmitted by the bite of an infected mosquito. There are 4 serotypes of the virus that causes dengue. These are known as DEN-1, DEN-2, DEN-3, DEN-4.

Severe dengue is a potentially lethal complication which can develop from dengue infections.

It is estimated that there are over 50-100 million cases of dengue worldwide each year and 3 billion people living in dengue endemic countries. Source: WHO. Link: https://www.who.int/vietnam/news/feature-stories/detail/dengue---questions-and-answers. Field: Infectious Disease. Disease: Dengue </s>