What does a positive tourniquet test indicate?

A positive tourniquet test indicates an increased likelihood of dengue fever. This test is specifically used as a clinical tool to assess for dengue hemorrhagic fever, which is a severe form of dengue virus infection. When the tourniquet is applied, it creates pressure that prevents blood flow and, if the small blood vessels are fragile due to the effects of the dengue virus, it can lead to the appearance of petechiae or purpura when the tourniquet is released. This reinforces the concern for bleeding disorders associated with dengue, thus indicating a higher probability of dengue fever in a patient exhibiting this sign.

The other options may suggest different conditions, but they do not directly correlate with the positive tourniquet test, which is specific to abnormalities related to the dengue virus. For instance, shock could be a sign of multiple severe infections or other systemic issues, while severe measles and pneumonia have their own distinct diagnostic criteria and clinical signs that do not involve the tourniquet test.