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MCQs in Tropical Medicine

Rob Skelly DTM+H FRCP

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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.

Copyright: Rob Skelly 2006