Which symptom is an early indication of smallpox?

The correct symptom that indicates an early sign of smallpox is the rash that starts around the mouth. In the course of smallpox, the initial phase often begins with flu-like symptoms such as fever, body aches, and malaise, but the defining feature of smallpox is the characteristic rash that develops. This rash typically appears within 1 to 4 days of the onset of fever, starting around the mouth and progressing to other parts of the body.

The importance of recognizing the rash is that it signifies the progression of the disease, differentiating smallpox from other illnesses with similar symptoms. This understanding is crucial in identifying and managing infectious diseases effectively, particularly in the context of public health. The timing and location of the rash are vital clues for clinicians and health professionals to pinpoint smallpox early, allowing for prompt isolation and control measures.