After an average incubation period of 4-6 days (range 3-14 days), various non-specific, undifferentiated prodomes, such as headache, backache and general malaise may develop. Typically, the onset of DF in adults is sudden, with a sharp rise in temperature occasionally accompanied by chillis, and is invariably associated with severe headache and flushed face(12). Within 24 hours there may be retro-orbital pain, particularly on eye movement or eye pressure, photophobia, backache and pain in the muscles and joints/bones of the extremities. The other common symptoms include anorexia and altered taste sensation, constipation, colicky pain and abdominal tenderness, dragging pains in the inguinal region, sore throat, and general depression. These symptoms vary in severity and usually persist for several days.

1. Fever: The body temperature is usually between 39oC and 40oC, and the fever may be biphasic, lasting 5-7 days.
2. Rash: Diffuse flushing or fleeting pinpoint eruptions may be observed on the face, neck and chest during the first half of the febrile period, and a conspicuous rash that may be maculopapular or scarlatiniform appears on approximately the third or fourth day. Towards the end of the febrile period or immediately after defervescence, the generalized rash fades and localized clusters of petechiae may appear over the dorsum of the feet, on the legs, and on the hands andarms. This confluent petechial rash is characterized by scattered, pale, round areas of normal skin. Occasionally the rash is accompanied by itching.
3. Skin Haemorrhage: A positive tourinquet test and/or petechiae.
4. Course: The relative duration and severity of DF varies between individuals in a given epidemic, as well as from one epidemic to another. Convalescence may be short and uneventful, but may also often be prolonged. In adults it sometimes lasts for several weeks and may be accompanied by pronounced asthenia and depression. Bradycardia is common during convalescene. Haemorrhagic complications, such as epistaxis, gingival bleeding, gastrointestinal bleeding, haematuria and hypermenorrhoea, may accompany epidemics of DF. Severe bleeding has occasionally caused deaths in some epidemics. Dengue fever with haemorrhagic manifestations must be differentiated from dengue haemorrhagic fever.