It is essential to consider the various forms of typhus as possible causes of fever in returning travellers. [ 10 , 11 ] Whilst Plasmodium falciparum malaria remains the most common and dangerous disease to exclude, the increasing incidence of typhus, particularly scrub typhus, across South and Southeast Asia, together with increasing resistance to standard treatment regimes, mean that this intracellular pathogen must always be considered in the differential diagnosis, particularly in travellers presenting with fever within three weeks of their return.
Diptera (two-winged insects) include mosquitoes, midges, gnats, and flies, all of which can act as disease vectors ( Table 4 ) . 19 Mosquito bites can spread West Nile virus, certain types of encephalitis, and, more recently, dengue fever, with cases reported in Key West, Fla., Hawaii, and Texas. 20 The vector for dengue fever is Aedes aegypti ( Figure 8 ) . Most mosquito bites in the United States provoke nothing more than an itchy welt. Typical bites appear as pruritic pink papules, often with a central punctum. Sensitivity varies widely, however, and some persons experience a severe or prolonged reaction. The more extreme cases have been termed skeeter syndrome, which describes an intense hypersensitivity reaction with fever related to allergens in mosquito saliva. 21 Antihistamines and prednisone are used to treat this condition.