Dengue fever mimicking acute appendicitis.

We report 12 patients [5 males, mean age 28 years (SD 4.6)] presenting with clinical features suggestive of acute appendicitis who were later diagnosed as having dengue fever (DF). Seven were admitted to hospital by surgeons and then referred to physicians due to thrombocytopenia (one of them following appendicectomy). Five were admitted to medical wards and then referred to surgeons due to abdominal pain. The mean time from onset of fever to abdominal pain was 2.2 d (SD 0.9). Clinical features included: right iliac fossa tenderness in 12 patients, rebound tenderness in nine, vomiting in nine, erythematous rash in eight, arthralgia/myalgia in eight, headache in six, diarrhea in three and palatal petechiae in three. All patients had C-reactive protein <12mg/l, and DF was confirmed serologically. Leucocytopenia and thrombocytopenia occurred by the third or fourth day of illness in all patients. Seven had free fluid around the appendix on abdominal ultrasound. The mean duration of abdominal symptoms and signs was 1.8 d (SD 1.3). DF may present with features suggestive of acute appendicitis in dengue-endemic areas. A carefully obtained history, clinical examination and a full blood count done on the third or fourth day of illness may help to differentiate DF from acute bacterial appendicitis.