Imported infections. Unexplained fever.

People returning from abroad frequently consult their general practitioners because of a febrile illness developing after arriving home. The cause of the fever may be immediately obvious when it is due to common conditions such as streptococcal tonsillitis or infectious mononucleosis. Sometimes, however, the doctor may be unable to make an immediate diagnosis and must consider the possibility that the patient is suffering from a communicable disease acquired abroad. The nature of the infection will depend on the areas of the world that the patient has visited. A traveller returning from Northern Europe or North America is unlikely to be suffering from an infection not normally prevalent in the United Kingdom, though the occasional outbreak of smallpox in northern countries must always be considered. Holidaymakers visiting Southern European countries may contract enteric fever, which may present with unexplained fever. Visits to North Africa or the Middle East take the traveller into malarious areas-which are widespread throughout Africa, Arabia, India, and the whole of the Indo-China peninsula. Malaria also occurs in Central and South America and in some areas of northern Australasia. Other causes of fever in patients returning from tropical countries include the typhus fevers, brucellosis, trypanosomiasis, filariasis, schistosomiasis, amoebiasis, kala azar, viral hepatitis, yellow fever, dengue, smallpox, and rare virus infections such as Lassa fever.