Final answer:
A sign of disease is an observable and measurable clinical manifestation that can be identified by a nurse, such as a change in vital signs like fever or abnormal blood test results.
Step-by-step explanation:
The clinical manifestation that a nurse should identify as a sign of disease is an objective and measurable indicator of an ailment, such as a change in vital signs. Clinical signs are directly observable by a clinician and may include body temperature, heart rate, breathing rate, and blood pressure. For example, a fever is a sign of disease because it represents a body temperature significantly higher than the normal 37 °C (98.6 °F) and can be measured. Other signs of disease could include abnormal results on blood tests, such as the presence of antibodies in a patient's serum, which is indicative of an immune response to a pathogen.