Dengue fever and dengue haemorrhagic fever--a diagnostic challenge.

The number of cases of dengue fever in returning travellers is increasing worldwide. In Australia, two mosquito vectors exist and the Aedes aegypti mosquito has already been responsible for local transmission within Queensland. For these reasons, general practitioners need to be able to recognise dengue fever and its complications: dengue haemorrhagic fever (DHF) and dengue shock syndrome. Infections can vary from severe to asymptomatic. The incubation period, duration of fevers, presence of rash and relative bradycardia can assist in the diagnosis of dengue. Dengue haemorrhagic fever is a severe form of dengue fever associated with plasma leakage and specific risk factors. The risk of DHF to most travellers previously infected with dengue is probably low. Serology and reverse transcriptase polymerase chain reaction are useful tests for diagnosing infection, although both have limitations. Vaccine design is a promising strategy to prevent infection.