[Use of the tourniquet test in diagnosing dengue-like syndrome]

A 26-year-old nurse presented with a three-day history of sudden onset of pyrexia of 39 °C, malaise, and a patchy maculopapular rash, after returning from a monthlong work in Senegal. A tourniquet was applied to help locate the vein for diagnostic blood sampling. After the procedure, a petechial rash erupted with a demarcation line below the level of the tourniquet. A diagnostic test for dengue fever was performed and confirmed by the polymerase chain reaction (PCR) to be positive for serotype DEN-1. The tourniquet test is performed by inflating a blood pressure cuff tied on the upper arm to a point midway between systolic and diastolic blood pressure for five minutes. The test is considered positive when there are 20 or more petechiae per square inch (6.25 cm(2)) on the forearm, and is one of several clinical parameters considered by the World Health Organization to be important in the diagnosis of dengue fever.