Confusion or reduced level of consciousness in the returned traveller

A large number of tropical infections can cause neurological syndromes but the returning traveller is more likely to have a condition that is well known to a UK physician. Malaria is the most commonly imported life-threatening tropical infection and should be excluded urgently in all patients. It is also important not to miss herpes encephalitis, bacterial meningitis and systemic infection, especially typhoid, as early treatment will change prognosis. Infections caused by arboviruses, such as Japanese B encephalitis, are rare but rabies and human African trypanosomiasis can cause a classical encephalitic presentation. HIV must always be considered, and non-infectious causes including drugs may be more common in travellers. A detailed geographical history is crucial and a systematic, logical approach based on incubation periods and geographical epidemiology can help to minimize unnecessary investigation.