Answer 41
Dengue fever
True a. is spread by the vector Aedes aegypti
False b. has an incubation period of 2-3 weeks
True c. is caused by a flavivirus
True d. characteristically causes severe myalgia
True e. is more likely to cause haemorrhage in patients previously infected by a Dengue virus
Dengue fever is at present the second most common cause of imported fever. Only malaria is more common as a cause of fever in travellers returning to the UK from the tropics. Enteric fever and hepatitis A are also common.
Dengue fever is particularly common in travellers to South East Asia but is widely distributed throughout the tropics.
The dengue virus is a single-stranded RNA virus, a flavivirus related to yellow fever virus. There are four serotypes.
The incubation period is short: about 4 days. Indeed viral infections should always be considered in those who develop fever within a week of arriving in a tropical area. The fever lasts about 4 days and may be biphasic ("saddleback").
The clinical presentation may be :
1. non-specific fever
2. Dengue fever syndrome characterised by severe myalgia
3. Dengue haemorrhagic fever / Dengue septic shock. This life-threathening form is more common in those previously infected. There is increased antibody production and DIC.
