Dengue infection is caused by the dengue virus that belongs to the family Flaviviridae.
There are 4 serotypes (DENV-1, DENV-2, DENV-3, DENV-4). Each serotype provides specific lifetime protective immunity against reinfection of the same serotype, but only temporary (within 2-3 months of the primary infection) and partial protection against other serotypes.
It is transmitted to humans through the bites of infected Aedes mosquitoes. It is primarily transmitted by female Aedes aegypti, a tropical and subtropical species. Humans are the main host of the virus.
After 4-10 days of incubation period, illness begins immediately.
Systolic blood pressure appears to have a strong association with aneurysmal subarachnoid haemorrhage (aSAH) but not with unruptured intracranial aneurysm (UIA), whereas current smoking and female sex are risk factors for both conditions, a study has found.